NASA-TM-86078 19840013861 

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- (NAS A-T M-8607 8) Fi.jNDAMENT At REMOTE SENS1NG 

SCIENCJ.d RES.t::AhCH Pi.<UliEi1M. Hftr 1: SCENE 

iADIATIU6 AND A1MGSPHEUIC EffECTS 

CHAliACrERIZA1ION FhCJ£Ci Status Rer:o['t 

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N84-21929 

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N84-21954 

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12583 

Technical Memorandum 86078 

R. E. Nh,U'phy and D. VV. Deering 

MARCH 1984 

National Aeronautics and 

Space Admlfilstratlon 

Goddard Spa:ce Fllf$ht Cooter 

Greenbelt, Maryland 20771 
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FUNDAMENTAL REMOTE SENSING SCIENCE 

RESEARCH PROGRAM PART I: 

STATUS REPORT OF THE SCENE RADIATION 

AND ATMOSPHERIC EFFECTS CHARACTERIZATION PROJECT 

R. E. Murphy 

Project Science Manager 

D. W. Deering 

Assistant Science Manager 

Earth Resources Branch 

Laboratory for Earth Sciences 

March 1984 

GODDARD SPACE FLIGHT CENTER 

Greenhelt, Maryland 20771 
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PREFACE 

With the continuing technological evolution of remote sensing from space, it is 

evident that we benefit from the technology only to the degree to which we 

understand the information captured in the remotely sensed image itself. Images 

of the Earth acquired from space vary according to the scene properties they 

portray. Images are dependf~nt on the natural variance in radiance from the 

Earth's surface, the effect of the atmosphere on the transfer of radiation, and 

the measurement capability of the ~ensor. What we can learn from orbital images 

depends on our ability to understand the transfer of electromagnetic energy 

from the Earth's crus~c through the atmosphere, and the absorption, emittance, 

and reflectance characteristics of both organic and inorganic materials of the 

Earth's surface. We must also be able to accurately register an orbital image, 

and the information contained therein, to its true location on the Earth's 

surface. Thus. with an understand i ng of energy trans fer from the target to the 

sensor and accurate procedures for geographical registration, we have the 

spectral and spatial attributes of an image that will allow us to infer the 

maximum amount of information from a scene. Some techniques that generate 

information from an image may be fundamental and generic in their application 

to the characterization of scene properties in all images. The development of 

generic techniques to advance our understanding of remotely sensed images 

represents an emerging, highly sophisticated science. 

The National Aeronautics and Space Administration, as an established sponsor of 

remote sensing technology research, has embarked on a specialized and continuing 

research program in fundamental remote sensing science. After an evaluation of 

major research needs, the agency has defined two significant projects: 

1. Scene rad ation and atmospheric effects characterization (SRAEC), and 

2. r1athematical pattern recognition and image analysis (MPRIA). 

In 1981, NASA sol icited research proposal s re1 ated to the hID projects from 

both the NASA and external science community. After a competitive evaluation 

of submitt?d proposals. NASA selected approximately 35 investigations and 

awarded funding in 1982. 

The investigations of both research projects strive to improve our understanding 

of scene properties. The t~'10 projects can be differentiated by the basic 

approach underlying each. The SRAEC project seeks to understa~d the fundamental 

relationship of energy interactions hetween the sensor and the surface target, 

including the effect of the atmosphere, to construct theoretical models predicting 

the radiance of the Earth's surface. Model inversions can then be applied to 

interpret the information contained in a space-acquired image of measured 

radiance. Conversely, the MPRIA project seeks to develop analytical techniques 

that group the radiance values contained in an image on a statistical basis to 

infer the properties of the scene. ultimately to understand the condition of 

the Earth's surface. An important component of MPRIA 1 ies in the development 

of technique for image georegis~ration and recognition of texture. The 

information associated with spatial patterns, or texture. of radiance in an 

image may contribute substantially to the inference of scene properties. 

PRECEDINC PAGE BLANK NOT FILMED" 

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l 

The Fundamental Remote Sensing Science Research Program supports the long-term 

goals of NASA in h/o significant ways. First, the techniques developed through 

the program enhance our ability to learn more about the physical and biological 

processes of our planet from space acquired data. Second, the results of the 

investigations contribute to a base of scientific understanding needed to 

support the planning of new and effective sensors and flight programs. 

This report is surymitted to describe the Fundamental Remote Sensing Science 

Research Program and the progress made since its initiation approximately two 

years ago. The report is represented in two parts. Part I provides the status 

of the Scene Radiation and Atmospheric Effects Characterization Project, 

primarily reflecting research results presented at the Second Annual Workshop for Investigators helrl at Colorado State University in Fort Coll ins, January 9-

11, 1984. Part II provides the status of the Mathematical Pattern Recognition 

and Image Analysis Project, which consists of current results and information • 

summarized from the proceerlings of the NASA Symposium on Mathematical ·Pattern 

Recognition and Image Analysis held June 1-3, 1983. 

Ry the end of 1984, NASA will announce a new opportunity for research in this 

continuing program. Topics for the solicitation of research will be defined in 

the months ahead and will be based on the outgrowth of results of present 

invest i gat ions and the fundamental research needs of other NASA programs that 

incorporate remote sensing for Earth observations • 

. -----r----

Guseman. Jr., L. F. 1983. Proceedings of the NASA Symposium on Mathematical 

Pattern Recognition and Ima~e Analy2.j~. June 1-3, 1983, Johnson Space Center, 

Houston, Texas. Contract NAS.9-16664~ Texas A&t1 University, Department of 

Mathematics, College Station, Texas. 

iv 

M. Kristine Butera 

Program Manager. Fundamental Remote Sensing 

Science Research 

NASA Headquarters 

Washington, D.C. 

.. 
.. 

• 

I • 

I I. 

FUNDAMENTAL REMOTE SENSING SCIENCE RESEARCH PROGRAM 

PART I: STATUS REPORT OF THE 

SCENE RADIATION AND ATMOSPHERIC EFFECTS CHARACTERIZATION PROJECT 

TABLE OF CONTENTS 

PREFACE 

SRAEC PROJECT OBJECTIVES . . . . . . . . . . . . . . . . . . . . . . . A. NASA Fundamental Remote Sensing Science Research Program. 

~. Relationship of SRAEC to NASA Objectives •• . . . . . . . . c. SRAEC Research Issues and Initial Focus 

SRAEC INVESTIGATIONS AND WORKSHOPS •• . . . . . . . . . A. Scope of Current Studies · . . . . . . . . B. First Annual Workshop 

C. Second Annual Workshop • . . . . . . . . . . . 

iii 

1 

2 

4 

6 

11 

12 

17 

18 

Ill. SRAEC RESEARCH RESULTS •• . . . . . . . . . 20 

A. SRAEC Project Progress and Accomplishments . . . . . . . . B. Inoividual Study Results Summaries (Ab-;tracts) •• 

C. Investigation Synopses. · . . . . . . . . . . . . . . . . 

21 

28 

48 

D. List of Puhlications and Presentations - SRAEC Project. • 239 

APPENDIX . . . . . . . . · . . . . . . . . . . . . . . . . . • 245 

A. SRAEC Project Investigators and Managers 246 

~. List of Workshop PartiCipants . . . . . . . . . . 248 

C. Second Workshop Agenda •••• 

Memorandum for the Record - K. Ruter~ 

v 

. . . . . . . . . . 249 •• 250 
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tN84 21930 

I.A. NASA FUNDAMENTAL REt10TE SENSING SCIENCE RESEARCH PROGRAt1 

NASA's research programs during the past decade that have addressed the 

use of remotely sensed measurements of the earth's surface have been typically 

of an applied nature. The satellite sensor designs of the 1970's were based 

largely on the laboratory, field and aircraft multispectral observations made 

in the 1960's, with limited understanding of cause-and-effect relationships 

between scene attributes and observed scene radiation. Similarly, the machine 

techniques for data analysis and information extraction have been hased largely 

on pattern recognition procedures, which ignore cause-and-effect as applied to 

satellite data labeling. In short, the development of rapid, empirical approaches 

to data interpretation has taken precedence over the development of a full 

scientific understanding of the earth-atmosphere scene radiation complex. 

The importance of remote, synoptic measurements of the earth's surface and 

atmosphere has been clearly demonstrateri, however, and the need and desire to 

fully utilize these powerful remote sensing measurements has reached the point 

where empirical techniques are no longer sufficient. The complex electromagnetic 

energy interactions among the various components of earth surface scenes and 

the atmosphere must be understood if further progress is to be made in remote 

sensing technology. Further advancement in both components and systems, hardware 

and software, and user confidence and use requires increased understanding of 

the characteristics of scene radiation and atmospheric effects at visible, 

infrared and microwave wavelengths. 

In order to meet this need for a more fundamental knowledge or understanding 

of earth radiation for supporting future space technology developments and 

applications research, NASA has established the Fundamental Remote Sensing 

Science Research Program within the land Processes Branch of the Earth Science 

and Applications DiviSion at NASA Headquarters. This fundamental research 

2 
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" 

01 

program currently contains two elements including (1) Scene Radiation and 

~tmospheric Effects Characterization, which this status report addresses, and 

(2) Mathematical Pattern Recognition and Image Analysis. 

The Fundamental Remote Sensing Science Reseach Program provides a dynamic 

scientific base that will be continually broadened and strengthened and from 

which future appl ied research and development can draw support. The Scene 

Radiation and Atmospheric Effects Characterization (SRAEC) Project element is 

bei ng conducted to improve our understand i ng of the energy emitted or refl ected 

from an earth surface target, through the intervening atmosphere as measured by 

a remote sensing system. 

3 

• 
.. 

I.B. RELATIONSHIP OF SRAEC TO NASA OBJECTIVES 

The Fundamental Remote Sensing Science Research Program's Scene Radiation 

and Atmospheric Effects Characterization Project is of a complementary nature 

to other NASA programs, but particularly focused upon providing the essential 

framework for future applied earth resources research projects. The study of 

the characteristics of radiant energy interactions with the earth atmosphere 

and earth surface elements is of fundamental significance to the general physical 

science community, but also has potential application in the NASA planetary 

programs for the interpretation of planet surface features from orbiting space 

probes. 

NASA is charted to expand human knowledge of phenomena in the atmosphere 

anc! to pursue practical benefits that can be gained from aeronautical and space 

activities. With man's eXRonentially increasing impact on both the earth's 

surface anc! the atmosphere, the need to measure and monitor these anthropogeni cally 

induced processes has become apparent to not only the scientific community but 

also the educated public as well. Thus, a Significant practical benefit to all 

of human-kind and other earth life forms will accrue from an improved capability 

to glohally sense and interpret earth surface features and changes through the 

atmosphere from space platforms. 

A new programmatic theme called Global Habitability, has thus developed 

within the Earth Science and Applications Division of the Office of Space Science 

and Applications. The overall objective is to investigate long-term physical. 

chemical. an0 biological trends and changes in the earth'S environment. including 

its atmosphere, land masses, and oceans. The program is intended to specifically 

investigate the effects of natural and human activities on the earth's environment 

by measuring and modeling important physical, chemical, and biological processes, 

and their interactions. The methodology involves the acquisition and analysis 

4 
of space and suhorhital observations. land-based measurements, modeling awl 

laboratory research. as well as supporting data management technologies over a 

ten-year or longer period of time. The product of the SRAEC project will he an 

improvect understanrling of the physical radiant energy interaction (remote 

sensing) processes through measurements and morleling that will ultimately enahle 

the proper specification of earth ohserving space sensor systems anrl the 

measurement and morleling of the important physical. chemical, and biological 

processes and their interactions. 

5 

• 
I.C. SRAEC RESEARCH ISSUES AND INITIAL FOCUS 

NASA organized and conducted a study during fiscal year 1980 to identify 

the fundamental research needs for future applications research in aerospace 

remote sensing. Through a series of ongoing workshops involving leading scientists 

from universities, industry and government, the Scene Radiation and Atmospheric 

Effects Characterization \"orking group identified specific priority research 

issues. These research issues, summarized briefly below, helped define the 

basis for a long term SRAEC fundamental remote sensing research project. 

The scene radiation and atmospheric effects research can be generically 

structured into four types of activities including observation of phenomena, 

empirical characterization, analytical modeling, and scene radiation analysis 

and synthesis. The first three activities are the means by which t~e goal of 

scene radiation analysis and synthesis is achieved. and thus are considered 

priority activities during the early phases of the current project. Scene 

radiation analysis refers to the extraction of information describing the 

biogeophysical attributes of the scerie from the spectral, spatial, and temporal 

radiance c~aracteristics of the scene including the atmosphere. It is the 

process by whi ch remotely sensed nata are exami ned for factors whi ch gi ve ri se 

to distinguishing characteristics between object scene classes or between levels 

of attributes within classes. Scene radiation synthesis is the generation of 

realistic spectral, spatial, and temporal radiance values for a scene with a 

given set of biogeop~ysical attributes and atmospheric conditions. In the 

past, most of the radiation characteristics of scene elements used for scene 

radiation synthesis were based on eillpirical characterizations. The addition of 

analytic models from the SRAEC research will strengthen this activity and 

simpl i fy data base structure and memory stoy·age. 

6 
-.... 

/ 

The SRAEC working group concluded that rJespite the differences in 

instrumentation and research techniques and approaches used by experimenters 

working in the various electromagnetic frequency regimes, there is a set of 

common needs that exists for all subcategories. These common needs or "themf. 

which the SRAEC project will address, include: 

II 

1) A neerJ for the systematic evaluation of existing scene mode'is (e.g. 

plant canopy models) including validation, verificati. n, and sensitivity 

analysis. 

2) A need to extend the existing models to heterogeneous media. 

3) A need to nevelop parameter estimation requirements, spec 'icaily for 

spatially distributed scenes. 

4) The overriding necessity to relate electromagnetic parameters to the 

classical biophysical descriptors. 

5) The lack of knowledge ahout the statistical rJistribution of the spatial 

anrJ temporal variability of the underlying parameters. 

6) The neerl to develop stronger links between experimental programs and 

theoretical work. 

7) The dichoto~ in problem conceptualization; that is, on the one hand. 

given a knowledge of the underlying parameters and appropriate 

mathematical descriptions. being able to predict response or conversely, 

given the measured response being able to infer scene attributes or to 

develop correction procedures. 

More specifically, research to be conducted within the SRAEC program is 

being focuserl on the development of empirical characterizations and mathematical 

process models which relate the electromagnetic (EM) energy reflected or emitted 

from a scene to scene characteristics. These parameters similarly need to be 

related to the biophysical parameters of interest. For example, the EM 

characteristics of vegetation canopies might be modeled in terms of the 

reflectance, transmittance. and absorptance properties of the leaves ar.d stems 

and in terms of the geometric orientation and distribution of the parts over 

the space occupi ed by the vegetat i on. A second morlel mi ght then be used to 

relate plant moisture deficiency levels to the 01 properties of the canopy 

7 
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parts and geometry. Such models could. therefore. support an analysis of the 

effects of different moisture deficiency levels on the EM radiation properties. 

Improved theoretical approaches to the study of the radiation characteristic 

of various types of earth resources are needed, particularly for renewable 

resources. There are significant limitations in the relatively few models that 

currently exist for the optical and microwave regions of the spectrum. Similarly 

empirical characterizations are limited and generall:, suffer from insufficient 

controls or lack of supporting data. The available models are constructed on 

assumptions that confine their use to restricted situations. Consequently. 

priority is being given to the development of improved theoretical and empirical 

approaches to the study of scene radiation. 

Observational studies are needed to empirically characterize the bidirectioni 

reflectance distribution functions, thermal properties, and microwave scattering 

characteristics of important earth resource classes (e.g., various crop canopies, 

forest canopies, sr,ow, soil types). The spatial and temporal variations of 

hiological and physical attributes of these classes must also be observed in 

order to characterize the effects of these variations on the reflected and 

emitted radiation. T~e spatial distribution of atmospheric scattering and 

absorbing components also requires observation and characterization to improve 

cllrrent models whic~ assume atmospheric uniformity in the horizontal dimension. 

There is a significant lack of unrterstanding of the distribution of the 

atmospheric scattering and ahsorption elements over geographic regions of 25 to 

75 square k i 1 orneters and larger. 

The empirical observations and charactprizations should lead to the 

formulation of rnathematic<ll process modE'ls which relate reflected and ernitterl 

radiation to scene attributes. The models Illust he based on sound biolo9ical 

ann physical principles which take into account the ohsprve1 biological and 
physical attributes of the earth resource targets and the atmosphere. Models 

are neec1erl for hoth indivic1ual resource classes and scenes containing a mixture 

of classes. ~~dels are also needec1 to c1escribe atmospheric variations over 

large areas. It is anticipateti that these atolospheric models will be developed 

through re~earch that is coordinated with empirical characterizations of natural 

terrain materials and plannecl in a design that will identify the natural 

variations of important atmospheric conditions at wavebands of interest over 

large areas. The applicability of existing atmospheric racliation models to 

neal with such variations could then be assessed anrl, if necessary, existing 

model s could he mod i fied or new ones developed to analyze important atmospheric 

effect s. 

Since funrlamental research is designed to support applied research activities 

the SRAEC working group consirlere1 that it may be useful to adclress general 

categories of questions which are neerled inputs to appl ied research. These 

general qupstions provider! a practical framework for prioritizing proposed 

funclamental research and included: 

1) What are the sppctral properties and differences in properties between 

various vegetative canopies as a function of relative differences in 

phenolog,y? Which features of these canopies give rise to these 

spectral differences? 

2) To loJhat degree are spectral di fferences in canopies ohscured by 

hackground effects such as variation in atmospheric haze and aerosols, 

soil background variations and variations in canopy density induced 

by varietal or ecotypical differences anrl cultural practices? 

3) How are the reflective and emissive properties of the canopy modified 

as a function of canopy conditions as influenced by drought stress, 

flooding, disease and insect rlamage? 

Thus, research investigations which will develop improved empirical and 

theoretical approaches to the quantitative characterization of electromagnetic 

radiation reflected and emitted from rene\~able resource scenes are being 

supported, as well as studies which will improve quantitative descriptions of 

9 
atmospheric scattering and absorption. The SRA£C studies that were initially 

selected and funded are described in Section II and will contribute to the 

capability for scene analysis and synthesis and will extend and strengthen the 

fundamental basis for applied remote senSing research. 

Areas of research needed that are not currently possible due to funding 

constraints include the theoretical integration of all wavelength regime (optica1-

reflective, microwave, thermal) modeling and the attendant coupled measurements 

program to support this activity. Thermal I'egime research is needed. 

Observational (measurements) support programs are essentially lacking, especially 

for non-agricultural areas. Atmospheric measurements programs are need~1 that 

require support at a more sophisticated funding level. Instrument development 

is significantly lacking for fundamental research needs. It is important to 

note that the early fundamental reserach activities have been able to piggyback 

to a considerable extent on observational studies previously supported by other 

major NASA programs (e.g., lACIE/AgRISTARS) that have "dried up." These current 

and future fundamental remote sensing research studies will suffer significantly 

unless a strong ohservationa1 base can be reestablished within the SRAEC project. 

10 
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II. SRAEC INVESTIGATIONS AND WORKSHOPS 

11 
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II.A. Scope of Current Studies 

Proposals from 0rganizat10ns outside NASA were officially solicited on 

July 27, 1981 and peer reviewed during December 8-11, 1981. The selected 

investigations are grouped into three categories and given by title, principal 

investigators and institutional affiliation in Table 11-1. The geographic 

locations of these investigators are shown in Figure 11-1 (see also Appendix 

A). The proposed research and funding were subsequently negotiated between the 

Science Manager and Principal Investigators to conform to the budgetary 

constraints. Each of the initial investigations cover two to three years of 

activity. The sixteen investigations can be logically grouped into three 

categories: 1) scene radiation studies at visible and infrared wavelengths, 

2) scene radiation studies at microwave wavelengths, and 3) atmospheric effects 

studies. 

Seven investigations have as their common theme' the understanding of 

visible and infrared radiation interaction with plant canopies. Heavy emphasis 

is placed on the theoretical development of mUlti-dimensional canopy reflectance 

models and on empi:ical characterizations of the bidirectional reflectance 

distribution function of various cover types and conditions. Individual, 

intensive laboratory and field measurement programs that relate biophysical 

variables to reflectance parameters complement the various modeling activit~es. 

One of the seven "canopy" studies (Diner) has emphasized atmospheric 

effects during the first 18 months and thus has been grouped with the atmospheric 

investigati0ns in the remainder of this report. Three other investigators have 

the atmosphere and its effects on earth resources remote sensing as their 

primary focus. Emphasis is on theoretical causes of the atmosphE~ric effects, 

the magnitude and variations of the atmospheric effects, and correction 

algorithms to account for the effects. Some field experiments to complement 

12 
Table II-I. SRAEe Project Principal Investigators, Institutional Affiliations, 

and Research Topics According to Three General Subject Categories. 

PRINCIPAL INVESTIGATOR INSTITUTION 

SCENE RADIATION STUDIES: 

Visihle and Infrared Wavelengths 

James Smi th 

John Norman 

Dan Kimes 

Vern Vanderbil t 

Alan Strahler 

Gautam Badhwar 

Dave Diner 

Microwave Wavelengths 

Ad ri an Fung 

Jin Au Kong 

Colorado State Univ. 

Univ. of Nebraska 

NASA/Goddard Space 

Flight Center 

Purdue Univ. 

Hunter Coll ege 

NASA/Johnson Space Center 

NASA/Jet Propulsion 

laboratory 

Univ. of Kansas 

t1assachusetts Inst. of Tech. 

... 

RESEARCH TOPIC 

Reflectance Modeling [Multidimensional 

Radiative Transfer Model Development and Extension] 

Bidirectional Reflectance Model ing of 

Non-Homogeneous Plant Canopies 

Comprehensive Understanding of Vegetated 

Scene Radiance Relationships 

Measurement and Modeling of the Optical 

Scattering Properties of Crop Canopies 

Reflectance Model [A Geometric Model for 

Heterogeneous Canopies of Partial Cover] 

The Relation Between Crop Growth and 

Spectral Reflectance Parameters 

Bidirectional Spectral R~flectance of 

Earth Resources: Influence of Scene 

Complexity and Atmospheric Effects on 

Remote Sensing 

Scattering Models in the Microwave Regime 

Remote Sensing of Earth Terrain 

I 
Table 11-1 (cont'd). SRAEC Project Principal Investigators. Institutional Affilations, and 

Research Topics according to the General Subject Categories. 

PRINCIPAL INVESTIGATOR 

Microwave Wavelengths 

Roger Lang 

Fawwaz Ul aby 

R. K. Moore 

Jack Paris 

Atmospheric Effects Studies 

Robert Fraser 

Will iam Pearce 

Siegfried Gerstl 

INSTITUTION 

Geo. Washington Univ. 

Univ. of Kansas 

Univ. of Kansas 

t~SA/Jet Propulsion 

laboratory 

NASA/Goddard Space Flight 

Center 

EG&G Washington Anal. 

Services Center 

los Alamos Nat" lab. 

RESEA.RCH TOP IC 

Discrete Random Media Techniques for 

Microwave Modeling of Vegetated Terrain 

Measuring and Model ing of the Diel'ectric 

Properties and Attenuation of Vegetation 

Measuring and Modeling of the Dielectric 

Properties and Attenuation of Vegetation 

Microwave Backscattering Properties of Crops 

Atmospheric Effect on Remote SenSing of 

the Earth's Surface 

The Characterization of Surface Reflectance 

Variation Effects of Remote SenSing 

Multidimensional Modeling ~~ Atmospheric Effects and Surface Heterogeneities on 

Remote Sensing 

'. 
fJ---

i .'& 

Figure 11-1. Geographic locations of the SRAEC principal investigators. 
.. 

the model development are being conducted. 

Six investigations are concerned with the microwave (active and passive) 

remote sensing potentialities. Emphasis is placed on measuring and understanding 

the backscatter properties of specific scene elements and the physical causes 

for these scattering properties. Scattering and emission models are also being 

developed and tested for vegetation, soil, and snow cover. 

Further details of the goals. objectives and accomplishments for the 

individual investigations are provided in Section III. 

16 
II.B. FIRST ANNUAL WORKSHOP 

The first meeting of the SRAEC principal investigators was held January 5-

7, 1983 at the University of Colorado in Boulder as a part of the National 

Radio Science Meeting. The SRAEC papers were presented in two sessions entitled 

"Optical and Microwave Studies of Vegetative Surfaces-I: Theoretical Investigation" 

and" • II: Observational Investigations". These sessions were chaired by 

Jin A. Kong and Daniel S. Kimes. respectively. 

Most of the SRAEC investigators had been under contract for only approximately 

six months by the time of this meeting, and consequently many of the investigator 

reports concerned the theoretical approaches being taken to address the problems 

under study and analysi~ of previously acquired data. 

The principal objective of this first meeting, however, was to bring this 

diverse group of investigators together to learn about the different SRAEC 

studies underway, share ideas, and foster syngergism and possible collaborative 

efforts. It was deemed particularly important to begin developing better 

communication bridges between the three major research topical areas; optical, 

microwave api atmosphere. 

Following the meeting Mike Calabrese (at that time the NASA Headquarters 

Renewable Resources Program Manager responsible for the SRAEC and MP~IA projects) 

wrote that the SRAEC Project "serves as an excellent forum to diSCUSS and 

articulate the merging of visible. IR, and microwave theoretical and experimental 

techniques. The investigators are beginning to show an awareness of this 

merger. I recommend that the upcomi ng ~torkshop add tess thi s merger by shari ng 

terminology and making tutorial presentations in their I'espective areas of 

expertise. The research could provide the 'tools' to conduct 'multispectral I 

science experiments on future shuttle missions." 

17 
II.C. SECOND ANNUAL WORKSHOP 

The second meeting of the. SRAEC principal investigators was held January 9-

11, 1984 at Colorado State Univeristy in Fort Collins. The National Radio 

Science ~1eeting was held in nearby Boulder during the latter part of the same 

week, thus enabling a concentrated SRAEC workshop and yet allowing those 

participating in the Radio Science meetings to conveniently attend both. The 

Fort Collins meeting was hosted by Jim Smith and the laboratory for Applications 

of Computers in Forestt~y at CSU. 140rkshop participants are 1 isted in Appendix 

B. 

The first half of the meeting consisted primarily of tutorial presentations 

on terms, measurements and concepts in the three principal SRAEC disciplines--

optical regime, m;crmolave regime and atmosphere (see .Appendix C--Second Workshop 

Age,da). The second half of the meeting was devoted to the principal investigator 

results presentations. In addition, Dick Heydorn, Sdence Manager for the 

Mathematical Pattern Recognition and Image Analysis (~RIA) Project gave an 

overview presentation on the MPRIA studies and hlo of the MPRIA investigators 

presented their individual investigations. The reaction to including the MPRIA 

presentations in the workshop was excell~nt. 

The meeting was highly interactive and provided a good mechanism for crossfetril fzation between discipl ines. It was originally tplhnned to separate into 

discipline focused splinter groups for discussion of :research issues, but the 

over\'1hel mi ng consensus among th(! pri nc i pa 1 invest i gatoirs was to stay together 

and share ideas on the important research topics and tllFe possibil ities for a 

joint experiment to support all of the modeling efforts. Time constraints did 

not allow a full development of these ideas and it was concluded that a further 

vlOrkshop in a few months was highly desirable. The tlweoreticians expressed an 

interest in developing closer contacts with the experimentalists, and the 
.. 

individual investigator reports proved to draw more discussion than time would 

permit at this meeting. 

The NASA Headquarters Remote Sensing Science Program Manager's comments on 

the meeting are given in Appendix D. The results presented at this meeting 

provide the basis for this status report and are presented as a project overvie\'1 

(Section III A), as individual study abstracts (Section III B), and as more 

detailed and graphically highlighted synopses (Section III C) 1n the fo11ol<ling 

section of this report. 

One strategic outfall from the annual meeting and workshop of the SRAEC 

principal investigators was an updating of the list of publications (Section 

III D) that has resulted from this fundamental research effort over the past 

1 1/2 - 2 years. SRAEC scientists have had significant progress and 

accomplishments that have resulted in the 35 journal articles--19 currently 

published and 16 in press. Seven additional papers have been submitted and 

are in revi e\'1 • 

", 
: .~. 

) 

III. SRAEC RESEARCH RESULTS 
( 

III.A. SqAEC PROJECT PROGRESS AND ACCOMPLISHMENTS 

SRAEC project investigators have made great strides in the theoretical 

development of plant canopy and whole scene modeling. New appro&ches to 

radiative transfer calculations have been formulated and validated. Greater 

understanding of the bidirectional reflectance of subcanopy elements and their 

role in canopy anistropic response has been gained, and variable surface 

reflectance interaction with the varying atmosphere is becoming a tractable 

problem. Important measurements of dielectric properties of vegetation are 

being made, and improvements have been made in the vigor of microwave vegetation 

models. This section of the report briefly summarizes some of the accomplishments 

according to the three general discipline categories: scene radiation studies 

in the visible and infrared r~gime. scene radiation st'ldies in the microwave 

regime and atmospheric effects studies. More detailed summaries are given in 

Sections III.B. and III.C. 

Optical-Reflective Regime 

The central theme of the scene radiation studies in the optical-reflective 

regime is to gain a greater understanding of the bidirectional reflectance 

properties of subcanopy elements (e.g. individual leaves). whole plant canopies 

and background surfaces and to dev~10p more accurate models of heterogeneous 

canopies or scenes. Most of the new data acquisitions are rather unique, as 

almost no data exists in the literature nn the bidirectional reflectance distribution 

functions (BRDFs) of subcanopy elements, canopies, and background soils. New 

technique and analysis procedure development are becoming necessary activities 

fo~ these studies. 

Subcanopy e"lement and soil measurement data analyses are reveal ing that 

current canopy model s must be incorrect in that they 1) use the wrong 1 eaf 

11 
" ' 

spectral (reflectance and transmission) properties due to individual leaf 

anisotropy (Norman), polarization (Vanderbilt) and the significant leaf 

specular contribution to total reflectance (Vanderbilt), 2) use normal inclination 

leaf refiectance rather than real leaf orientation characteristics that give 

rise to anisotropy of reflectance (Kimes, Norman). and 3) assume lambertian 

soil background reflectances which are invalid (Kimes, Norman, Smith). Attempts 

are being made to incorporate this new knowledge into the various canopy models 

and some early success has been achieved (Kimes, Smith). 

Current evidence from model results and validation measurements is that 

tl"O primary mechanisms cause the directional scattering of complete, homogeneous 

canopies. The first is caused by shadowing gradients and view projection 

gradients within the canopy and the second is the primary directional scattering 

of the leaves due to leaf orientation, source direction, and leaf reflectance 

and transmittance values (Kimes). Sparse or heterogeneous canopies are more 

difficult to interpret but have a strong dependence on the soil background. 

Models may in fact have difficulty distinguishing bet\~een rough soils and sparse 

canopies without combining wavelength and angular information together in a 

single, comp1!x formulation (Norman). 

The shadowing problem is being studied through a modeling and field study 

at a larger "scene" scale for discontinuous conifer forest canopies, wherein 

the trees are considered as collections of conical forms that are illuminated 

at an angle and cast shadows on a contrasting background (Strahler). Currently, 

an earlier invertible geometric model has been successfully modified to correct 

for the reduction in shadow and canopy area that occurs when shadows fallon 

crowns .• ~ tree crowns intersect (overlap). 

In addition to the aforementioned studies that attempt to model canopies 

on the spatial or three-dimensional scales, one investigation is examining 

22 
"'",' 

canopy reflectance on the temporal scale for ascertaining vegetation types and 

characteristics from spectral transform trajectories (Badhwar). A mathematical 

technique that maximizes the sensitivity of spectral transformation to Leaf 

Area Innex and simultaneously minimizes the sensitivity to all other variables 

has been formulated and successfully tested for two canopy types. 

~'icrowave Regime 

Somewhat analogous to the subcanopy element reflectance measurements in 

the optical-reflective regime are the microwave dielectric properties and 

backscatter sources measurements of vegetation material being performed in the 

microwave/radar regime studies. The amount of data acquired thus far in only 

one of these studies is at least an order of magnitude greater in volume than 

the total cumulative amount of data report..;.~ i" the literature to date. Heavy 

emphasis during the first year and one half has been on developing new techniques 

for 1 aboratory and fi eld meaSllI·~~f11entc;. 

Field measurements with a 10 GHz radar system showed that the portion of a 

plant canopy that is the primary source of the backscatter differs for different 

plant canopy types and conditions (Moore). Typically, the top cluster of le?ves 

in green plant canopies are the main backscattering source for 300 incidence 

angles (e.g., corn, milo, soybean). However', upon f11aturation either the lower 

portions of the stalks or stems or the seen head are the dominant sources. For 

vertical incidence an . .'Gs greater penetration into soybean canopies occurred 

such that 14 dB of a total 17 dB loss was due to the lower portion of the plant 

where the stems are located. For corn, however. the top leaves were still the 

dominant backscatter source (22 dB total loss). 

These results are supported in a single-scattering/canopy structure model 

validation experiment using corn and wheat measurements. The use of explicit 

leaf hiophysical parameters (and the ignoring of stalk and fruit parameters) in 

23 
, IIllIlDft • 

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the mortel led to a significant improvement in the goodness of fit of the model 

predictions to the observations [for example, at 17 GHz with VV polarization, 

the r2 increased from 0.79 to 0.93], and SIGMA for an average corn leaf was 

founrt to have a excellent (r2 of 0.97) power law relation to average green leaf 

area. Such a rtramatic increas,e in the fit of the model will allow scientists 

to extract desired canopy parameters such as leaf area index and areal leaf 

water content from radar backscattering measurements and will pave the way for 

, t, 

better empirical experiments to investigate the fundamental causes of backscatter 

by vegetation (Paris). 

In another study oiel ectric measurements at three microv/ave wavel engths 

were made of the liquid includec1 in vegetation l'1aterial after extraction by 

mechanical means (Ulahy). These measurements explainec1 the heretofore unexpected 

frequency behavior of the dielectric constant of the vegetation-water mixture. 

It has always been assumed in the literature that the attenuation coefficient 

of vegetation increases with increasing frequency because its dielectric constant 

is proportional to that of pure water. It was found in this investigation that 

the water contained in the vegetation materials has a salinity of 10 to 15%, 

which results in a vegetation dielectric constant that is ahout 15 times larger 

than that previously expecteo at 1 GHz. This means that the propagation loss 

is more than an order of magnituc1e greater than had previously been assumed. 

These results are expecte<1 to have a significant effect on the future development 

of models of emission and scattering from vegetation canopies (Ulaby). 

Three of thE! 1'1; cr-owave invest i gat ions have been more strongly ori entefi to 

theoretical model development. In the past, rough surface scattering and volume 

scattering were treated independently as two separate fields of study. One of 

the modeling investigations combines the techniques in the two areas using the 

radiative transfer method (incoherent transport theory) to provide a more 

24 
./ ./ .. -

realistic terrain scattering model and permits the study of the interaction 

between surface and volume scattering (Fung). Another uses both coherent and 

incoherent techniques wherein vegetation is modeled by discrete scatterers such 

as leaves, stems, branches and trunks, which have been replaced by lossy 

dielectric disks and cylinders. Rough surfaces are represented by their mean 

and spectral characteristics and average scattered power is then calculated by 

employing discrete random media methodology, such as the distorted Born 

approximation or transport theory (Lang). The third study has developed an 

anisotropic random media model together with a discrete scatterer model with 

nonsprerical particles for vegetation fields due to the strong azimuthal 

dependence in the observed data. However, the investigator has also developed 

numerous theoretical models that are deSigned for active and passive remote 

sensing of plowed fields and snow fields as well as atmospheric precipitation 

(Kong). 

From rough surface/volume scattering model investigations, rough surface 

scattering was found to be important at near vertical observations (enhances 

cross-polar;zed scattering) and volume scattering from layer inhomogeneities 

was found to dominate scattering (like and cross polarized) at large incidence 

angles (Fung). The discrete scatterers model calculations showed that leaves 

dominated the backscatter return for HH polarization i>lhile stems were important 

for VV polarized returns at large angle of incidence (Lang). 

In a companion modeling effort it was found that scattering measurements 

are more sensitive to soil moisture changes than emission measurements because 

while both types of measurements lose sensitivity to soil moisture because of 

the vegetation layer. the loss is greater for passive than active measurements 

(Fung) • 

25 
Atmospheric Effects 

The atmospheric effects studies at the present time are primarily theoretical 

modeling studies designed to determine the principal causes and magnitude of 

the atmospheric effects on the remote sensing of earth surface features. The 

coupling of atmosphere and canopy reflectance models is beginning to evolve. 

Four of thE' SRAEC investigations have emphasized the atmospheric transport 

medium. Considerable effort during the early phases of these studies has 

involved the development and modification of radiative transfer codes for remote 

sensing applications or to handle non-uniform and nonqlambertian surfaces and to 

improve computational efficiencies. 

Considerable interest in these atmosphere studies has centered on the 

nature and magnitude of the atmospheric "point-spread" function or adjacency 

effect. The influence of atmospheric scattering has been found to extend 

several kilometers from each surface point {Diner. Fraser, Pearce}. A laboratory 

simulation experiment was conducted to verify the existence of the adjacency 

effect (the effect of a bright field on the radiance detected above a dark 

field) and was used to test 3-D radiative transfer models (Fraser). The 

adjacency effect was shown to reduce the separability between surface classes 

(in addition to its effect on spatial resolution and classification accuracy). 

This new effect is present when the field size is of the order of the atmospheric 

scale height (Fraser). 

Theoretical computations that compare cases in which increasing amounts of 

aerosol are shifted in the stratosphere, v/hile maintaining a constant optical 

depth, show that the effect on the spread function is to scale it linearly as 

would be expected from a single scattering model (Pearce). The aerosol absorption 

effect was found to be stronger for high than low surface reflectances, but the 

aerosol optical thickness was dominant for small surface reflectances (Fraser). 

26 
Remote sensing of contrast, such as with the Vegetation Index, is only weakly 

affected by aerosol absorption but is affected by aerosol scattering (Fraser, 

see also Gerstl). 

Preliminary investigation of anisotropic leaf scattering characteristics 

appear to produce only negligible effects on satellite measured data above the 

atmosphere. Additionally, non-Lambert1an and specular surface reflectance 

characteristics (BRDF) seem to affect satellite measurements at nadir only 

insignificantly, but can make large differences for off-nadir observations 

(Gerstl). 

One encouraging new technique development, based on the different spatial 

characters of radiation directly and diffusely transmitted to space, may enable 

determining atmospheric optical depth from an orbiting spacecraft (Diner). 

27 
III.B. INDIVIDUAL STUDY RESULTS SUMMARIES 

(ABSTRACT S ) 

28 
J. Smith 

,} . Norman 

D. Kimes 

V. Vanderbil t 

A. Strahler 

G. Badhwar 

D. Diner 

III.B.1. SCENE RADIATION STUDIES--OPTICAL REGIME 

Reflectance Modeling n1ultidimensional Radiative Transfer 

Model Development and Extension] 

Bidirectional Reflectance r~odeling of Non-Homogeneous Plant 

Canopies 

Comprehensive Understanding of Vegetated Scene Radiance 

Relationships 

Measurement and Modeling of the Optical Scattering Properties of Crop Canopies 

Pefl ectance r·10ctel [A Geometri c Model for Heterogenous Canopies of Partial Cover] 

The Relation Between Crop Growth and Spectral Reflectance 

Parameters 

(see III.B.3) 

29 

\ 

\ 

. V' REFLECTANCE MODELING II 

J. Smith. K. Cooper and M. Randolph 

Colo. St. Univ. 

We completed our classical description of the one-dimensional radiative transfer 

treatment of vegetation canopies and tested the results against measured prairie 

(blue grama) and agricultural canopies (soybean). Our phase functions are 

calculated in terms of directly measurable biophysical characteristics of the 

canopy medium. While the phase functions tend to exhibit backscattering 

anisotropy, their exact behavior is somewhat more complex and wavelength 

dependent. Comparisons with classical Rayleigh and Henyey-Greenstein 

formulations are given. A main advantage of this formulation is its compatibility 

with other atmospheric investigators in the program. Several areas for extension 

are suggested by the \</ork of Gerstl, Norman and Kimes involving individual leaf 

optical anisotropy and leaf azimuth orientation. 

A Monte Carlo model has been developed that treats soil surfaces with large 

perioc:\'ic variations in three dimensions. A photon-ray tracing technique is 

used. Currently, the rough soil surface is described by analytic functions and 

appropriate geometric calculations performed. A bidirectional reflectance 

distribution function is calculated and, hence, available for other atmospheric 

or canopy reflectance models as a lower boundary c().ldition. The authors have 

used this technique together with their adding model to calculate several cases 

where lambertian leaves possessing anisotropic leaf angle distributions yield 

non-Lamberti an reflectance, similar behavior is exhibited for our simulated soil 

surfaces. ' 
I 

/ 
, 

" - ... ~ 

\'-. NS4 21932 

BIDIRECTIONAL REFLECTANCE MODELING OF NON-HOMOGENEOUS PLANT CANOPIES 

~v~. ('\' " "-\ ~ ~"'~"\\ i I'\.l\ 

J~ Norman \:\ 'v \ 

U. of Nebr. ' 

The main objective of this research is to develop a three-dimensional model to 

predict canopy, bioirectional reflectance for heterogenous plant stands using 

incident radiation ann canopy structural descriptions as inputs. During the 

first year we have developed utility programs to cope ~~ith the complex output 

from the 3-dimensional model and begun cooing of the 3-D model. In addition we 

have attempted to define leaf and soil properties. which are appropriate to the 

mode. by measuring leaf and soil birlirectional reflectance distributlJn functions; 

since almost no data exist on these distributions. In the process we have come 

to believe that most models probably are using the wrong leaf spectral properties, 

and that off-nadir reflectance measurements are difficult to make because of 

non-Lambertian properties of reference surfaces. Also. in the visible wavebands, 

rough soil ~ay not be distinguishable from canopies when viewed from above. 

,." 

CW84 21933 

COMPREHENSIVE UNDERSTANDING fOR VEGETATED SCENE RADIANCE RELATIONSHIPS 

AJM:t..L 5. 

D. Kimes and D. Deering NASA/GSFC 

The overall objective of the three·~ear study is to improve our fundamental 

understanding of the dynamics of directional scattering properties of vegetation 

canopies through analysis of field data and model simulation data. The specific 

first and second year objectives were to (1) collect directional reflectance 

data covering the entire exitance hemisphere for several common vegetation 

canopies with various geometric structure (both homogeneous and row crop structures), 

(2) develop a scene radiation model with a general mathematical framework 

which will treat 3-D variability in heterogeneous scenes and account for 3-D 

radiant interactions within the scene and (2) expand 3-0 model to include 

anisotropic scattering algorithms at the "cell" level, (3) conduct initial 

validation of model on row crop data sets, and (4) test and expand proposed 

physical scattering mechanisms involved in reflectance distribution dynamics 

by analyzing both field and model ing data. 

Directional reflectance distributions spanning the entire exitance hemisphere 

were measured in two field studies; one using a Mark III 3-hand radiometer and 

one using the newly developed rapid scanning bidirectional field instrument 

called PARABOLA. Surfaces measured included corn, soyheans. bare soils, grass 

lawn, orchard gra5s, alfalfa, cotton row crops, plowed field, annual grassland. 

stipa grass, hard wheat, salt plain shrubland. and irrigated wheat. In addition, 

some structural and optical ~easurements were taken. Analysis of field data 

showed unique reflectance distributions ranging from bare soi1 ~o complete 

vegetation canopies. Physical mechanisms causing these trends were proposed 

based on scattering properties of soil anrl vegetation. Soil exhibited a strong 

backscattering peak toward the sun. Complete vegetation exhibited a "bowl" 

distribution with the minimum reflectance near nadir. Incomplete vegetation 

canopies showed shifting of the minimum reflectance off of nadir in the forward 

scattering direction because both the scattering properties of the vegetation 

and soil were being observed. 

The 3-D model was developed and is unique in that it predicts (1) the directional 

spectral reflectance factors as a function of the sensor's azimuth and zenith 

angles and the sensor's position ahove the canopy, (2) the spectral absorption 

as a function of location within the scene, and (3) the directional spectl'a1 

radiance as a function of the sensor's location within the scene. Initial 

verification of the model as applied to a soybean row crop showed that the 

simulated directional data corresponded relatively well in gross trends to the 

measured rlata. The model was expanded to include the anisotropic scattering 

properties of leaves as a function of the leaf orientation distribution in 

both the zenith and azimuth angle modes. The model was applied to complete 

vegetation canopies of various geometric structures, and it was found lhat the 

unique canopy reflectance distribution characteristics ;orere supported by the 

initial field measurements. The dynamics of these distributions were physicn1ly expla'ined by directional scattering effects of two mechanisms. 

32 

N84 21934 

MEASURH1ENT AND MODELING OF THE OPTICAL SCATTERING PROPERTIES OF CROP CANOPIES 

\.:\/~i. t' 

V~ Vanderbilt an1 L. Grant 

This research is measuring, analyzing. and mathematically modeling the specular, 

polarized. and diffuse light scattering properties of several plant canopies 

and their component parts (leaves. stems, fruit. soil) as a function of view 

angle and illumination angle. The potential of these bidirectional radiation 

properties for ground cover discrimination and condition assessment is being 

evaluated. To properly characterize the phenomena at various scales and to 

investigate the effect of the atmophsere, measurements are being made in the 

laboratory and in the field and will he n~de from a light aircraft. 

During the first year, our objectives were (1) to demonstrate our new technique 

for determining the specular and diffuse components of the reflectance factor 

of plant canopies, (2) to acquire the measurements and begin assembling a data 

set for developing and testing canopy reflectance models. (3) to design and 

build a ne~1 optical instrument to measure the 1 ight scattering properties of 

individual leaves, and (4) to use this instrument to survey and investigate the 

information in the light scattering properties of individual leaves of crops, 

forests, weeds, and horticulture. 

In achieving each of these objective, we have discovered several new results. 

For the wheat canopies used to demonstrate our new technique, specularly 

reflecterl light was as much as 50% of the total reflected light for some 

view/illumination directions. And for indivirtual corn leaves, 85% of the light 

reflected at the Brewster angl€ was found to be specular, This means that 

specular light cannot he ignored for purposes of rnodeliny the canopy reflectance. 

Both the specular anrl diffuse portions of leaf reflectance factor vary 

Significantly with species -- and the specular portion is possibly a major source 

of noise in OK-2 type reflectance rnesaurements ~n chlorophyll absorption regions 

of indivirlual leaves. Furthermore, our results suggest it is virtually impossible 

to separate for most species the spectll ar and diffuse components of leaf 

reflectance using a DK-2 with integrating sphere. 

Finally, our results include the discovery of two relationships potentially 

useful. for assessing the condition of remotely sensed crops. He found a linear, 

inverse relationshp beb/('(~n the relative water content (R'HC) of corn leaves and 

their diffuse reflectance factor in the rert wavelength region. The relationship 

appears valid even for an RWC greater than 80% where other investigators have 

founrl the mirldle infrarerl hemispherical leaf reflectance to be a poor estimator 

of QWC. Another result we found is a linear relationship between the severity 

of wheat rust on a leaf and the specular portion of its reflectance factor. 

33 

rW84 21935 

REFLECTANCE MODELING 1/." \1 

Ii:. Strahler (, ,I' .pL-\ Hunter Coll ege I (~ \tb.-{If'~· \ 

~t~ \ ., ~ 

The broad objective of this research 1s to increase our general understanding 

of the bidirectional reflectance distribution function of vegetation (primarily, 

forest) canopies. The main thrust of the work being conducted at Hunter College 

is in the modeling of spectral responses of discontinuous conifer forest 

canopies, considered as collections of conical forms that are illuminated at an 

angle and cast shadows on a contracting background. This work leads from the 

development of an early invertihle coniferous forest canopy reflectance model 

that allowed direct estimation of the height and spacing of conifers from the 

pixel-to-pixel variances of image brightness values in Landsat scenes. The 

three first-year objectives are now complete. These are: (1) modification of 

the variance-driven model to incorporate overlapping of shadows and crowns; 

(2) collection and analysis of photographic data to calibrate tree-spacing functions; and (3) collection of field data to determine height, spacing, and 

shape of conifers in open and closed stands in the Goosenest (California) test 

area. 

Modification of the invertible model uses a linear approximation to correct for 

the recluction in shadow and canopy area that occurs when shadows fan on crowns 

or tree crowns intersect. Comparison of the results of the approximation with 

a series of T10nte Carlo simulations ShOl1S that the mean area covered by cro~ms 

or shadows is approximated quite accurately, but the variance calculated departs 

significantly from simulated values. The analysis of tree spacing patterns 

using air photos showed that spacing tended to be somewhat regular at a scale 

approximately equal to the average distance between trees, but at larger distance 

scales counts of trees in cells could be approximated acceptably by a Poisson 

(random) function. Field measurements show that the short-distance regularity 

observed on air photos is an artifact of the inability to distinguish individual 

trees when their crowns overlap significantly, and that trees of the same size 

are often found growing in close proximity. 

For the remainder of the second year, work will continue on inverting the 

overlapping model and on analyzing the field data to incorporate observed 

height, spacing, and fOI'01 functions into the model. Additional efforts will be 

developed to assemble and register data from Thematic t1apper simulator. Landsat 

4 MSS, SPOT simulator, Airborne Imagining Spectrometer, and a 30-m digital 

terrain model in order to he1 p val idate the model. 

34 

• • 

N84 21936 

A STUDY OF THE RELATION BET~;~[N CROP GROWTH 

AND SPECTRA REF~ECJANCE PARAMETERS 

\\1,,.\.,',,,).· \1 

G. l3adhv/ar 

NASA/JSC 

The hasic broader objectives of this research effort are: (1) To investigate 

the dynamic behavior of canopy reflectance versus time and the relationship 

that such trajectories bear t canopy dynamics, for example, ontogeny and 

morphology. (2) To understand which transformations of spectral data are "best" 

for observing key canopy characteristics, such as Leaf Area Index (LAl) and 

vegetation identification. (3) To formulate physical basis for understanding 

how various spectral transform trajectories depend on vegetation type and 

interaction of reflectance in chlorophyll and water absorption bands to monitor 

stress. (4) As part of the physical understanding process, evaluate and improve 

canopy rad i at i ve transport model s. 

As part of first year objectives, a differential equation describing the temporal 

behavior of greenness, G(t). with time was developed. The basic equation, dG~ = k(t)(l-~ ) where Gm is the saturation value of greenness at time, tp' 

cit Gm It has been, demonstrated that k(t). has the form of a law, k(t)=2[1/t + l/tp-t] 

and that k(t) is linearly proportional to the rate of change of leaf area inHex. 

This provides, a technique to estimate leaf area index. 

It was demonstrated that Gm• tR and profile ~/idth, , are the key to vegetation identification and that the inflection points of the profile are related to the 

ontogeni c state of the pl ant. These profil e feature l'Jere shown to hol d not 

only throughout the United States corn/soybean grovdng area, but for the fi rst 

time in Argentina. 

Having demonstrated the power of these features to obtain vegetation characteristics, 

we \oJi sh to understand why these features provide the best separat i on. A number 

of canopy reflectance models have been implemented and are being tested on corn 

and soybean data set s. They will be used to ga in th is understand i ng. 

A mathematical technique that maximizes the sensitivity of spectral transformation 

to Leaf Area Index an( simultaneously minimizes the sensitivity to all other 

variables was formulated. Initial results on corn and wheat have been obtained. 

35 
A. Fung 

J. Kong 

R. lang 

F. Ulaby 

R. Moore 

J. Paris 

-

III.R.2. SCENE RADIATION STUDIES-MICROWAVE REGIME 

Scattering Models in the Microwave Regime 

Remote Sensing of Earth Terrain 

Discrete Random Media Techniques for Microwave Modeling of 

Vegetated Terrain 

e)J); i 

----

Measuring and Modeling of the Dielectric Properties and Attenuation 

of Vegetation 

Determinaticn of the Sources of Radar Scattering 

Microwave Backscattering Properties of Crops 

3G 

21937 

SCATTERING MODELS IN THE MICROWAVE REGIME h.~M-\\ \--. 

~, !,~",,}J\ t.: Fung ~~" \ ... ,. \.JJ U. of Kansas 

The goal of the first year effort wa~ to calculate scattering from an inhomogeneous 

layer with irregular boundaries to model natural terrain such as a layer of 

vegetation or sea ice. The inhomogeneities were modeled by spherical or discshaped discrete scatterers which were small compared with the incident wavelength 

and were in the far field of one another. It was found that the cross-polarized 

scattering was dominated by multiple scattering effects and was sensitive to 

the orientations and distributions of the scatterers. This model has been 

applied to interpret measurements from vegetation, snow and sea ice. 

The goal of the current year is to extend the scattering model developed in the 

first year to handle disc-shaped scatterers which are comparable to the incident 

wavelength and to use the scattering model to investigate the relative merits 

between active versus passive sensing of soil moisture over vegetated terrain. 

Results indicate that scattering measurements are more sensitive to soil moisture 

changes than emission measurements. This is because while both types of 

measurements lose sensitivity to soil moisture because of the vegetation layer, 

the loss is greater for passive than active measurements. 

In the third year the goal is to further iMprove the volume scattering portion 

of the model to permit close spacing between scatterers and to generalize the 

surface scattering portion of the model to include roughness scales comparable 

to wavelength. This should provide a general and more realistic terrain 

scattering model than what is currently available. 

37 

RE~lOTE SENSING OF}ARTH TERRAIN 

V\,·hlA· 1 ~t, JA}~ 

J. Kong \(,.,:I.J-~ \,~t- ,.) 

M. I. T. tIJ..-v/ftt--1U-t..<.I 

The purpose of our investigation is to develop theoretical models that are 

useful and practical in relating remote sensing data to the important physical 

parallleters characterizi ng earth terrai n. Our work is geared to\'/ard devel opi n9 

models that are useful in data analysis and interpretation, scene simulation, 

and developing new remote sensing approaches and techniques. In the first year 

we have developed numerous theoretical models that are applicable to the active 

and passive remote sensing of plowed fields, atmospheric precipitation, 

vegetation, and snow fields. 

The development of our theoretical models has been strongly motivated by the 

need to interpret the data obtained from various types of earth terrain which 

show distinctive characteristics. The problem of microwave scattering from 

sinusoidal surfaces has been studied to explain the large differences in the 

radar backscattering cross sections and the radiometric brightness temperatures 

between the cases where the incident wave vector is parallel or perpendicular 

to the row direction. The radiative transfer theory is used to interpret the 

active and passive data as a function of rain rate. Roth the random medium 

model and the discrete scatterer model is used to study the remote sensing of 

vegetation fields. Due to the non-spherical geometry of the scatterers there 

is strong azimuthal dependence in the observed data. Thus, the anisotropic random medium model awl the discrete scatterer model vlith nonspherical particles 

have been developed. 

In order to relate the remote sensing data to the actual physical parameters, 

we have studied scattering of electromagnetic waves from randomly distributed 

dielectric scatterers. Both the rigorous random discrete scatterer theory and 

the strong fluctuation theory are used to derive the bad;scattering cross 

section in terms of the actual physical parameters and the results agree well 

with the data obtained from the snow fields. 

'JJ/O 

" 

~lV84 21939 

Microwave remote sensing of agricultural crops and forested regions has been 

studied. Long terM goals of my research involve modeling vegetation so that 

radar signatures can be used to infer the parameters which characterize the 

vegetation and underlying ground. Vegetation is modeled by discrete scatterers 

viz, leaves, stems, branches and trunks. These have been replaced by glossy dielectric discs and cylinders. Rough surfaces are represented by their mp~n 

and spectral characteristics. Average scattered power is then calculated by employing discrete random media methodology such as the distorted Born 

approximation or transport theory. Both coherent and incoherent multiple scattering techniques are explored. Once direct methods have been developed, 

inversion techniques can be investigated. 

During the first year scattering amplitudes were calculated for resonant but 

electrically thin discs and stems. Trunks were modeled by infinitely long dielectrit: cyl-jnders. A coherent distorted Born theory was developed directly 

from Maxwell·s equations for collections of scatterers having sizes comparable 

to a wavelength. Backscattering cross-sections for like and cross polarized 

returns were calculated for a multi-component vegetation layer. Cross-sections 

were also calculated by employing a low albedo expansion of the vector transport 

equations (incoherent theory). It was ShOrln that the two methods yielded results within 3 db of each other for like polarizations; the two theories gave substantially different results for cross polarized returns. Both methods 

required that the albedo of the scatterers or the optical depth of the layer be 

small. As a consequence, the results were restricted to frequencies below 4 

GHz for agricultural crops. 

The coherent d i:>torted Born theory was used to cal cul ate the backscatter from a 

mature soybean crop. Both leaves and stems were modeled as thin dielectric 

scatterers. Physical statistics were used to characterize the distribution of 

leaf and stem sizes. Results of the calculations compared favorably with 

University of Kansas returns which were reported in the literature. The 

calculations showed that leaves dominated the backscatter return for HH 

polarization while stems were important for VV polarized returns at large angles of incidence. 

39 

.. .. P'~ 

1- i~84 21940 ., J.. 

MEASURING AND NODELING OF THE DIELECTRIC PROPERTIES AND 

ATTENTUATI?N ,Pf,~GETATION , • , 

t,\..I' , , ); , It \,., I·' t { ·l' .. t, 

F Ul aby ?tr II" \! \ I I~. ./, A... ; • ,',' \..>-''''' ..• v U. of Kansas '\ 

, 

The objectives of this investigation were: (1) to measure the dielectric 

properties of vegetation material--primarily agricultural plants--as a function 

of moisture content and microwave frequency, (2) to develop dielectric mixing 

models for the vegetation-~Jater mixture. (3) to develop a model for the loss 

factor of a vegetation canopy. and (4) to relate the results of (1) and (2) to 

(3). These objectives were successfully realized; in addition. a number of 

interesting new results were obtained. 

During the first phase of this investigation, three waveguide transmission 

systems covering the 1 - 2-GHz. 3.5 - 6.5-GHz. and 7.5 - 8.5GHz bands were 

constructed and ca'i ibrated. By measllring the magnitude and phase of the field 

transmission coefficic~t of a given sample. it was possible to calculate the 

real and imaginary parts of the complex dielectric constant of the sample. 

Measurements ~/ere made for numerous sampl es of 1 eaves and stal k s of wheat. and 

corn, and for wheat heads. Also. dielectric measurements were made of the 

1 iquid included in the vegetation material after extraction by mechanical means. 

These measurements expl ai nect the heretofore unexpected frequency behavi or of 

the dielectric constant of the vegetation-water mixture. It had always been 

assumed in the literature that the attenuation coefficient of vegetation increases \'Jith i ncreas i ng frequency because its d i e1 ectrl c constant is proport i onal 

to that of the pure water. We found in this investigation that the water 

contained in the vegetation material has a salinity of 10 to 15 0/00, which 

results in a vegetation dielectric constant that is about 15 times larger than 

that previously expected at 1 GHz. This means that the propagation loss is 

more than an order of magnitude greater than had previollsly been assumed. He 

expect these results to have a significant effect on future development of 

models of emission and scattering from ~egetation canopies. 

Various types of dielectric mixing models were investigated in terms of the 

available ctata, and a propagation model was developed and evaluated against 

direct canopy attenuation measurements. The canopy measurements were made by transmitting a signal from a radar antenna mounted atop a truck-mounted boom. 

and us i ng a sma 11 antenna mounted on a ra il beneath the canopy to recei ve it. 

Add i t i onal canopy attenuat i on measurements are pl anned for the Spri ng and Summer 

of 1984. 

40 

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i 

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~ 

~ N84 21941 

DETERMINATION OF THE SOURCES OF RADAR SCATTERING 

/'J R~"Moore and R. Zoughi 

. \ '. \., '." U. of Kansas 

:. M., ~, . '. \ \ \ 

• \ \ I\. '. .' 

The field of terr~}~-scattering is still in its early stages of development. 

Several theoretical techniques are available which have established the general 

behavior of the backscattering coefficient ( ) for the various vegetation 

canopies. ~lost of these techniques aSSUr.1e the vegetation canopy to be a 

homogeneous medium with some statistically known parameters. To develop a 

better backscattering model for canopies important properties such as attenuation 

and major backscattering source locations should be known. Fine-resolution radar 

backscattering measurements were proposed to determine the backscattering 

sources in various vegetation canopies and surface targets. The results were 

then used to improve the existing theoretical models of terrain scattering, and 

also to enhance understanding of the radar Signal observed by an imaging radar 

over a vegetated area. 

Various experiments were performed during the first year (1983) on targets such 

as corn, milo, soybeans. grass, asphalt pavements. soil and concrete walkways. 

Due to the lack of available references on measurements of this type, the 

obtained results will be used primarily as a foundation for future experiments. 

This year was also a learning period regarding the constituent backscattering 

characteristics of the vegetation canopies. 

The second and third years I'lill be dedicated to performing more experiments and 

using the results to improve the existing models. They should be more fruitful 

because of a better understanding of the problems associated with these types 

of measurements. A new radar system will also be developed to improve the 

measurement accuracy • 

41 

tN84 21942 

EFFECTS OF VEGETATION CANOPY STRYCTURE ON MICROWAVE SCATTERING 

I}..L/\ t, 

J. Pari s 

NASA/JPL 

The broad goal of this study is to increase the understanding of the role of 

canopy structure on microwave backscattering. Structure refers to the size, 

orientation, and vertical pl acernent of scatterers in the canopy. The first 

year objectives I'lere (1) to develop model s to predict the backscattering 

coefficient. SIGMAO. of vegetation with explicit biophysical and explicit polarization~ependent parameters and (2) to prepare for field measurements 

with radar scatterometers. 

:])/3 

Concerning technical progress, I accomplished the following: (1) the modification 

of the Attema and Ulaby (1977) model and its multilay~r variation by Hoekman et 

al. (1983) to include polarization explicitly (i.e., to allow for separate 

backscattering cross sections. SIGMA, and extinction cross sections, 0, for 

each polarization), (2) the investigation of the modified model to isolate 

canopy element orientaticn parameters by the ratioing of SIG~1AO me~surements 

for different polarization combinations, (3) the development of expressions 

for bistatic scattering and canopy-substrate scattering to supplement the 

models, (4) the performance of sensitivity analyses on these models, (5) the 

modification of the Attema and Ulaby model to a11O'.'I for changes, (6) the use 

of the modified model with a seasonal corn data set from Kansas (Eger et al., 

1903), and (7) the initiation of preparations for empirical measurements with 

the JPL radar spectrometer and the Mobile Radar Scatterometer in irrigated cropland to test the models.' 

Out of these efforts. I found the foll o;'Ii ng: (1) the model form for cross 

polarization was significantly different than that for like polarization, 

(2) the use of ratios of SIGMAO for different polarization combinations can 

isolate canopy element orientation parameters. (3) the canopy parameters, SIGMA, O. and NAL (the number of scattering elements per unit area). play separate 

roles according to the thickness or density of the canopy. (4) canopy-substrat" 

interactions can add significant contributions to the overall SIGMAO, (5) the 

use of explicit leaf biophysical.,Qarameters (and the ignoring of stalk andfrui t parameters) in the modelled to a s~i fi ca~rovement in the goodness 

of fit of the model predictions t,o th~ observations [for example, at 17 GHl 

with VV polarization. the rz---rncreased from 0.79 (that tger et a1., 1983. 

obtainedLto 0.9311, and (6) ,SIGHA for~~age corn leaf. was found to have 

an excel!..~!l~ (rTof 0.97) pO_~Jer la\~ relation_to average 9r~en leaf area. Such 

a dramatic lncrease in the fit of the ;,lOdel I'/i11 allow scientists to extract 

desired canopy parameters slIch as leaf area index and areal leaf water content 

from radar backscattering measurements and will pave the way for better empirical 

experiments to investigate the fundamental causes of backscatter by vegetation. 

42 
R. 

F W. 

r 

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I S. 

" ~ 

" 

I D. 

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Fraser - Pearce -

Gerstl 

Diner 

III.B.3. ATMOSPHERIC EFFECTS STUDIES 

Atmospheric Effect on Remote Sensing of the Earth's Surface 

The Characterization of Surface Reflectance Variation Effects 

of Remote Sensing 

Multidimensional Modeling of Atmospheric Effects and Surface 

Heterogeneities on Remote Sensing 

Bidirectional Spectral Reflectance of Earth Resourcse: Influence 

of Scene Complexity and Atmosp.heric Effects on Remote Sensing 

43 

( 
/ 
._- . 

,.--- . 

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'" • '. -... JUt 

: N84 21948 

ATMOSPHERIC EFFECTS ON REMOTE SENSING OF HIE EARTH'S SURFACE 

/'I~d f' 

R. Fraser and Y. Kaufman 

NASA/GSFC 

-::DIY 

The objective of the investigation is to determine the main causes and magnitude 

of the atmospheric effects on remote sensing of the earth's surface. The 

investigation includes theoretical study as wellas measurements. The knowledge 

gained from this study will be used to develop atmospheric correction algorithms 

and to test them with satellite data. 

In a theoretical investigation of the relative effects of the aerosol optical thickness, absorption, and size distribution on remote sensing, it was found 

that aerosol absorption ha~ a significant effect on satellite measurements of 

surface reflectivity. The absorption effect is stronger for high than for low 

surface reflectances. The aerosol optical thickness is dominant for small 

surface reflectances. The accuracy of clustering algorithms depends on both 

parameters. The vegetation index, however. is affected by the optical thickness 

but only weakly affected by the absorption (Fraser and Kaufman, 1983). 

A laboratory simulation of the atmospheric effect on the radiance of sunlight 

scattered from the earth's surface-atmosphere system was performerl. This 

experiment verified the existence of the adjacency effect (the effect of a 

bright field on the radiance detected above a dark field) and was used to test 

3-0 radiative transfer model s' (Mekl er, Kaufman and Fraser', 1983). 

In a theoretical study it was found that atmospheric scattering resulting from 

the adjacency effect reduces the separability between surface classes. This 

ne\'/ atmospheric effect is present when the field sizels of the order of the 

atmospheric scale height (Kaufman and Fraser, 1983). 

A field experiment is being conducted to measure the path radiance simultaneously 

with measurements of the aerosol optical thickness scattering phase function, 

atmospheric scattering coefficient at the surface. and the sky polarization. 

The measurements (partially completed) will be used to test the correlation 

between the atmospheric effects and the aerosol characteristics. 

44 

. • 

~ 

~ 

~; 

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! 

! 

! 

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.;, 

21944 .. - CHARACTER IZA TION OF SURFACE REFLECTANCE ,VAR IGAT ION EFFECTS ON REMOTE SE NS ING 

(,j)j,P\ /1 

W~); Pearce 

EG&G 

Our overall goals include tnt:! use of our ~lonte Carlo radiative transfer codes 

to simulate the effects Of! remote sensing in visible and infrared wavelengths 

of variables which affect classification. These include detector viewing angle, 

atmospheric aerosol size distribution, aerosol vertical and horizontal distribution 

(e.g. finite clouds). the form of the bidirectional ground reflectance function, 

and horizontal variability of reflectance type and reflectivity (albedo). 

These simulations are to be used to characterize the sensitivity of observables 

(intensity and polarization) to variations in the underlYing physical parameters 

both to improve al gorithms for the removal of atmospheric effects ano to identi fy 

techniques which Cdn imp,'ove classification accuracy. 

During the first year of this effort our first objective was to revise and 

validate our simulation codes (CT~ANS. ARTRAN. and the Mie scattering code) to 

improve efficiency and accommodate a new operational environment. Next, it was 

necessary to build the basic software tools for ac~uisition and off-line 

manipulation of simulation results. These included micro-to-mainframe 

communications. graphics, fast Fourier transform, 1 inear filtering and cubic 

spline differentiation, integration, and interpolation. The atmospheric spread 

function is of prime interest in characterizing the effects of the atmosphere. 

It is available in one riimensional form either through differentiation (of 

intensities in the vicinity of an albedo boundary) or as the Fourier transform 

of intensities sensed over a sinusoirlally varying ground albedo pattern. Since 

Monte Carlo resul ts are inherently no; sy. it was necessary to impl ement and 

test techniques to damp the noise \o'/hile preserving the essential accuracy of 

the results. Our initial investigation of the effects of vertical profile 

variability provided a test bed. 

Our initial calculations compare cases in which increas§l1g amounts of aerosol 

are shifted into,the stratosphere, maintaining a consta!l'lt optical depth •. In 

the case of moderate aerosol optical depth, the effect rIO the spread function 

is to scale it linearly as would be expected from a si:figle scattering moclel. 

Varying the viewing angle appears to provide the same Qual itative effect as 

modifying the vertical optical depth (for Lambertian ground reflectance). 

45 

I 

~ 

! 

I 

I I 

I 

"'" 

,..N84 21945 

... ... .... --- ~\JLTIDIf'4,ENS10NAL f'bDEUNG OF AnIOSPHERIC 

EFFECTS PHJ SuRFACE HrnFpGENEIpES ON Ra/OTE SENSIt\!G 

\~':1 tutC (1· , 

$. Gerstl j\lJ n.-vk-.-~i /..lt~-

Los Alamos Natl. Lab. 

The overall goal of this project is to establish a modeling capability that 

allows a quantitative determination of atmospheric effects on remote sensing 

including the effects of surface heterogeneities. Our first year objectives 

include (a) the adaptation of existing radiative transfer codes to remote 

sensing applications, (b) the implementation of a realistic atmospheric data 

base, (c) the definition and verification against field measurements of a 

--f) 

-It, 

coupled atmosphere/canopy model, (d) the quantitative characterization of the 

effects of some biophysical canopy parameters and soil surface boundary conditions 

on satellite-sensed MSS data. These objectives have been achieved and are 

being documented in refereed journal publications. Substantial progress has 

also been made in quantifying the effects of varying atmospheric turbidity and 

different non-Lamberti an and specular ground reflectances on MSS data and its 

transforms like Greenness and Brightness. 

Our most significant scientific findings provide quantitative substantiation 

for the following conclusions: 

(1) Atmospheric effects are the major contributions to LANDSAT MSS bands A and 

B (visible) ~lhi1e they play only a minor role in f.1SS bands C and 0 (near IR). 

The Kauth-Thomas greenness parameter remains invariant to large variations of 

atmospheric turbidity while the MSS brightness parameter is found nearly 

proportional to the atmospheric optical depth over uniform vegetative surfaces. 

(2) The inclusion of anisotropic leaf scattering characteristics in our canopy 

model is significant to explain reflectance measurements directly above the 

canopy but produces only negligible effects on s1tellite-measured data above 

the atmosphere. 

(3) Non-Lambertian and specular surface reflectance characteristics (BRDF) 

affect satellite measurements at nadir only insignificant'y but can nake large 

differences for off-nadir observations. 

These results bear significance to scene identification and at~ospheric effects 

correction algorithms as well as to canopy reflectance model~n9 efforts. 

46 

\-NS4 21946 ~ . 

BIDIRECTIONAL SPECTRAL REFLECTANCE OF EARTH RESOURCES: 

INFlIJEI'ICE OF SCENE COHPLEXITY AND ATMQSPHER IC EFFECTS ON REMOTE SENSING 

i)A\. -\ ' 

D. Oi rier 

NASAjJPL 

The overall objective of this research program is to develop pract;~al methods 

for remote sensing when scene complexity and atmospheric effects modify intrinsic 

reflective properties. We concentrate in particular on the radiation history 

from ground to space of 1 ight reflected from individual leaves; the radiation 

is initially multiply scattered within the crop canopy. whose geometry provides 

a controlling influence, then scattered and attenu~ted as a result of transmission 

through the Earth's atmosphere. We are developing the experimental and 

theoretical tools for studying these effects quantitatively. 

We have developed a new radiative transfer code which uses Fourier transforms 

tc solve the 3-0 equation of transfer. Our initial version permits inhomogeneous 

non-Lambertian surfaces but assumes horizontal uniformity for the atmosphere. 

Our computational results are in excellent agreement with f\'oOnte Carlo caiculatiolls. 

We verify previous studies which indicate that the influence of atmospheric 

scattering extends several kilometers from each surface point. We have also 

found that the width of the atmospheric "point-spread" function increases with 

increasing aerosol scale height- and Viewing angle relative to the nadir. We 

have develope<"! a technique baser1 on the different spatial characters of radiation 

directly and diffusely transnritted to space for determining atmospheric optical 

depth from an orbiting spacecraft. Numerical simulations using the 3-D code 

and including the effects of noise are extremely encouraging. 

We are using laboratory apparatus to study the variation of spectral reflectance 

of individual leaves as a function of illumination incidence angle and reflection 

angle. These data can then be used in models to determine canopy scattering effects. Our initial objective has been to develop reliahle spectral and 

angular reflectance standards. We have found it necessary to modify the existing 

apparatus by strengthening the frame and replacing some optical elements. We 

have ohtained some preliminary spectra of camellia and cucumber leaves in the 

0.4 - 0.9 micron range. Greatest departures from Lamhertian reflectance are 

seen in the 0.68 mi cron chlorophyll absorpti on feature. He have a1 so performed 

stress tests by observing leaf reflectance at 0.9 microns as a function of time 

following clipping from the stem. A reflectance increase due to loss of water 

has been observed. 

We are currently developing a more sophisticated 3-D radiative transfer algorithm which permits horizontal inhof)1.Q.,\;jeneity in the atmosphere as well as the surface. 

In addition to the utility of this method to atmospheric studies, we anticipate possi~e application to canopy modeling, treating plant canopies as a sort of 

scattering "atmosphere". 
III.C. INVESTIGATION SYNOPSES 

Synopsis Elements: 

a. Broad Goals and Investigation Objectives 

b. First Year Objectives 

c. Technical Progress and Accomplishments 

d. Results/Scientific Findings 

e. Significance to General Research Area 

f. Relationship to Other Fundamental Research SRAEC Investigations 

g. Second Year Objectives 

h. Study Participants and Affiliations 

i. Publications (SRAEC supported research) 

j. Key Visuals/Illustrations 

"'-,-. 
""" 

• 

J. Smith 

J. Norman 

.---.-- D. Kimes 

V. Vanderbil t 

A. St rahl er 

G. Badhwar 

I) • Diner 

.\ 

--. 

III.C.l. SCENE RAOIATION STUDIES--OPTICAL REGIME 

Reflectance Modeling n1ultidimensional Radiative Transfer 

Model Development and Extension] 

Bidirectional Reflectance Hodeling of Non-Homogeneous Plant 

Canopies 

Comprehensive Understanding of Vegetated Scene Radiance 

Relationships 

Measuremp.nt and ~'odel lng of the Optical Scattering Properties 

of Crop Canopies 

Refl ectance Model [A Geometric Nodel for Heterogenous 

Canopies of Partial Cover] 

The Relation Between Crop Growth and Spectral Reflectance 

Parameters 

(see III.C.3) 

49 . 

I 

.. 
/ 

" 

REFLECTANCE MODELING 

J. Smith. K. Coopp~ and M. Randolph 

Colo. St. Univ. 

INVESTIGATION SYNOPSIS 

A. BROAD GOALS AND INVESTIGATION OBJECTIVES 

~ GENERAL UNDERSTANDING OF BRDF (BIDIRECTIONAL REFLECTANCE DISTRIBUTION FUNCTION) 

, DEVELOP AND EXTEND BRDF MODELS FOR HETEROGENEOUS CANOPIES OF 

PARTIAL COVER 

-ESPECIALLY PROCESS-ORIENTED MODELS DRIVEN BY PHYSICAL 

PARAMETERS AND MEASUREMENTS 

B. FIRST-YEAR OBJECTIVES 

, COLLECT AND IMPLEMENT VEGETATION CANOPY REFLECTANCE MODELS 

, BEGIN MORE FORMAL DESCRIPTION OF RADIATIVE TRANSFER PROBLEM IN CLASSICAL 

ATMOSPHERIC SCIENCE CONTEXT TO AID JOINT CANOPY/ATMOSPHERE MODELING 
.:a. , 1 

C. TECHNICAL PROGRESS AND ACCOMPLISHMENTS 

D. RESULTS/SCIENTIFIC FINDINGS 

e COMPLETE CLASSICAL RTE DESCRIPTION OF VEGETATION 

CANOPIES 

-CALCULATION OF PHASE FUNCTIONS UTILIZING 

BIOPHYSICAL DESCRIPTIONS OF CANOPY MEDIA 

-SENSITIVITY ANALYSIS 

-DISTRIBUTE TO ATMOSPHERIC WORKERS 

3 INITIAL DEVELOPMENT OF MONTE CARLO SOIL REFLECTANCE 

MODEL FOR 3D SURFACES 

-INCORPORATION INTO ADDING VEGETATION REFLECTANCE 

MODEL FOR INITIAL CUT AT 3D SOIL EFFECTS WITH 

VEGETATED SURFACES 

-POTENTIAL APPLICATIONS TO NON-RENEWABLE RESOURCES 
.. 

E. SIGNIFICANCE TO GENERAL RESEARCH AREA 

o PROVIDES DIRECT SUPPORT FOR SCENE ANALYSIS~ ATMOSPHERIC STUDIES~ OTHER 

MODELING EFFORTS AND MEASUREMENT PROGRAMS 

t SUPPORTS PREDICTION OF OPTICAL-REFLECTIVE RESPONSES TO VEGETATION 

CANOPIES 

F. RELATION TO OTHER FUNDAMENTAL SRAEC INVESTIG.~TORS 

• DIRECTLY RELATED TO~ AND COORDINATED WITH} STRAHLER) NORMAN 

t COULD INCORPO~ATE/RELATE TO WORK BY TUCKER~ VANDERBILT~ RIMES~ GERSTL 

G. SECOND-YEAR OBJECTIVES 

~ , EXTEND PHASE FUNCTION DESCRIPTIONS TO INCLUDE GERSTL THEORETICAL LEAF N 

ANISOTROPY TREATMENT/INDIVIDUAL LEAF BRDF's 

i EXTEND PHASE FUNCTION DESCRIPTION TO INCLUDE KIMES LEAF AZIMUTHAL 

ANISOTROPY DESCRIPTION 

e EXPLORE MULTIDIMENSIONAL RTE EXTENSIONS - INCO~PORATION INTO KIMES APPROACH 

, DEVELOP SOIL THREE DIMENSIONAL REFLECTANCE MODEL COMPATIBLE WITH 

VEGETATION MODELS 

CSU/SMITH/1-9-84/p.3 
()"I 

w 

H. STUDY PARTICIPANTS AND AFFILIATIGriS 

@ GRADUATE STUDENTS --

-M. H. RANDOLPH (PH.D. SUMMER 1983) 

-K. C. COOPER (PH.D. EXP. 1985) 

@ COLLABORATORS 

-A, H. STRAHLER~ HUNTER COLLEGE 

-J. M. NORMAN) U. NEB. 

I. PUBLICATIONS 

THESES: 

M. H. RANDOLPH. 1983. A RADIATIVE TRANSFER EQUATION/PHASE FUNCTION 

APPROACH TO VEGETATION CANOPY REFLECTANCE MODELING. PH.D. THESIS~ 

COLORADO STATE UNIV.~ FORT COLLINS. 

MANUSCRIPTS SUBMITTED: 

M. H. RANDOLPH. 1984. A RTE PHASE FUNCTION DESCRIPTION OF VEGETATION 

CANOPIES. SUBMITTED TO IEEE TRANS. GEOSC. & REM. SENSe 

MANUSCRIPTS IN PROGRESS: 

K. D. COOPER AND J. A. SMITH. 1984. A f10NTE-CARLO REFLECTANCE MODEL 

FOR SOIL SURFACES WITH 3D STRUCTURE. 

CSU/SMITH/1-9-84/p.4 

\ 
~ 

U1 

..". 

SYI'lPOS IA: 

." 

\ 

.', ~ 

P. M. TEILLET, R. BROWN, J. A. SMiTH, AND G. FEDEREJEUS. 1983. 

REFLECTANCE MODEL STUDIES AT THE CCRS INTERNATIONAL COLLOQ, 

ON SPECTRAL SIGN. IN REM. SENSe BORDEAU, FRANCE. 

CSU/SMITH/1-9-84/p.5 

· .. ·c -. --'''_J;;~ 

!!' 

" 

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BIDIRECTIONAL REFLECTANCE MODELING OF NON-HOMOGENEOUS PLANT CANOP IES 

J. Norman 

U. of Nebr. 

BROAD GOALS 

'DEVELOP A 3-D ~10DEL TO PRED I CT CANOPY J 

BIDIRECTIONAL REFLECTANCE FOR 

HETERGENEOUS PLANT STANDS USING 

I~CmENT RADIATION AND CANOPY STRUCTURE 

DESCRIPTIONS AS INPUTS 

YEAR - 1 OBJECTIVE 

DEVELOP UTILITY PROGRAMS TO HANDLE OUTPUT 

FROM 3-D HODEL 

DEFINE LEAF SPECTRAL PROPERTIES REQUIRED 

BEGIN CODING 3-D ~ODEL 

f1EASUR[ SOME SO I L BID I R. RfFLECTANCES 

55 

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UTILITY PROGRAMS HAVE BEEN DEVELOPED. 

(SEE EXAf1PLES) 

SEVERAL LEAF BIDIRECTIONAL REFL. MEASURED. 

SIMPLIFIED 3-D r10DEL CODED BUT UNSATISFACTORY. 

8 SOIL BIDIR. REFL. MEASURED - 3 SOIL ROUGHNESSES. 

RESllLTS 

LEAF REFL. AND TRANS. STRONGLY DEPENDENT ON 

SUN AND VIBI A~GLES. 

REFERENCE SFC. REFL. DEPENDENT ON SUN AND 

VIEW ANGLES. 

LEAF HEMISPHERICAL REFL. DEPE~DENT ON SUN 

INCIDHlCE ANGLE. 

SIMPLIFIED 3-D MODEL CONTAINS MORE HORIZONTAL 

AVERAGING THAN IS DESIRABLE. 

EIDIR. REFL. OF ROUGII SOIL "LOOKS" LII<E CANOPY. 

BIDIR. REFL. OF SMOOTH SOIL APPROXIMATES 

LAf'lBERTIAN SURFACE. 

56 
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SIGNIFICANCE 

CANOPY RADIATION MODELS HAVE REEN USING 

NORMAL-INC LEAF REFL. SO NOT THE 

CORRECT VALUES. 

REFERENCE SURFACES MAY HAVE TO BE CORRECTED 

FOR NON-LAf1BERTIAN CHARACTER FOR OFF-NAD I R 

REFL. f1EASUREf1ENTS, 

IT il4 Y BE D IFF I CULT TO D ISTI nGU ISH BEHJEEN 

r,ETWEEN ROUGH SOILS ArID SPARSE CANOPIES 

\HTHOUT Cm1BINING H,~VELENGTH AND ANGULAR 

INFORMATION TOGETHER IN A SINGLE) Crn1PLEX 

FORf1ULATION. 

RELATION TO OTHER F. R. HORK 

OHlER FoR. NODELING PROJECTS (SfI1ITH) NEED 

APPROPRIATE LEAF AND SOIL SPECTRAL AND 

ANGULAR PROPERTIES I 

F. R. MEASUREMENT PROJECTS INVOLVING 

OFF-NADIR WORK SHOULD CONSIDER REFERENCE 

ANGULAR PROPERTIES . 

73 

, . 

.. 
~ .. , 

.. 

\ 

YEAR - 2 OBJECTIVES 

cm1PLETE CODING OF 3-D" BIDIR CANOPY 

REFL.. NODEL. 

INCORPORATE SOIL BIDIR. REFL. IN 1-D 

AND 3-D CANOPY MODELS 

OBTAIN A RELATION BETHEEN HHlISPHERICAL 

LEAF REFLECTANCE AND SUN INCIDENCE ANGLE. 

STUDY PARTI C I PANTS 

GRAD STUDENT (FULL TIME) - RETTY HALTER 

GRAD STUDENT (PART TI~E) - JON WELLES 

CONSULTANT - G,~YLON CAMPBELL 

AFFILIATIONS 

JIM Sr'1ITH 

DON DEERING 

PUBLICATION (PARTIAL SUPPORT SRAEC) 

NORMAN" J. M. AND J. M. WELLES" 1983. RADIATIVE 

TRANSFER IN AN ARRAY OF CANOPIES. AGRO~, J. 

75:481-488. 

74 

1'. 
I 

/ 
IV 

• 

~N84 21947 .... 

COMPREHENSIVE UNDERSTANDING FOR VEGETATEO SCENE RADIANCE RELATIONSHIPS r .' 

j D. Kimes and D. Deering NASA/GSFC 

Broad Goals and Investigation Objectives 

Improve our fundamental understanding of the dynamics of directional 

scattering properties of vegetation canopies through analysis of field 

data and model simulation data. 

First year objectives: 

Collect directional "eflectance data covering the entire exitance hemisphere 

for several common vegetation car.opies (both homogeneous and row crop 

structure). 

• Develop a scene radiation model with a general mathematical framework 

which will treat 3-0 variability in heterogeneous scenes and account 

for 3-D radiant interactions within the scene. 

o Conduct initial validation of model on row crop data sets. 

Second year objectives: 

• Continue to collect reflectance distributions of vegetation canopies with various geometric structure 

• Expand 3-0 model to include anisotropic scattering algorithms at "cell" 

level. 

• Continue to test and expand proposed physical scattering mechanism 

involved in reflectance distribution dynamics by analyzing bo}h field 

and modeling data. 

Results/Scientific Findings 

• 

• 

Directional reflectance distributions spanning the entire exitance hemisphere 

were measured in two field studies; one using a Nark III 3-band radiometer and 

one using the newly developed rapid scanni'ilg bidirectional field instrument 

called PARABOLA. Surfaces measured included corn. soybeans. bare soils, grass 

1 awn, orchard grass, a1 fa1 fa, cotton row crops, plowed field, annual grassl and. 

stipa grass, hard wheat, salt plain shrubland. and irrigated wheat. In addition. 

some structural and optical measurements were taken. 

Analysis of field data showed unique reflectance distributions ranging 

from bare soil to complete vegetation canopies. Physical mechanisms 

causing these trends were proposed based on scattering properties of 

soil and vegetation. Soil exhibited a strong backscattering peak toward 

the sun. Complete vegetation exhibited a "bowl" distribution with the 

minimum reflectance near nadir. Incomplete vegetation canopies showed 

shifting of the minimum reflectance off of nadir in the forward scattering 

direction because both the scattering properties or the vegetation and 

soil were being observed. 

75 

( 
'\ 

-, , 

• The 3-D model was developed and is unique in that it predicts (I) the 

directional spectral reflectance factors as a function of the sensor's 

az imuth and zen ith ang I es and the sensor's pos it i on above the canopy, 

(2) the spectral absorption as a function of location within the scene, 

and (3) the directional spectral radiance as a function of the sensor's 

location within the scene. 

Initial verification of the model as applied to a soybean row crop 

showed that the simulated directional data corresponded relatively well 

in gross trends to the measured data. However, the model can be 

greatly improved by incorporating more realistic anisotropic scattering 

properties. The model was shown to follow known physical principles or 

radiative transfer. The model explained in physical terms the "bowl" 

shape distribution of complete vegetation canopies. 

• The 3-D model was expanded to include the anisotropic scattering 

properties of leaves as a function of the leaf orientation distribution 

in both the zenith and azimuth angle modes. 

• The model was applied to complete vegetation canopies of various 

geometric structures--erectophile, planophile, spherical, and 

heliotropic. It was found that each canopy had unique reflectance 

distribution characteristics which were supported by the initial field 

measurements. The dynamics of these distributions were physically 

explained by directional scattering effects of two mechanisms. The 

first mechanism causes the characteristic "bowl" shape or complete 

canopies. It is caused by shadowing gradients and view projection 

gradients within the canopy. The second mechanism is the primary 

directional scattering of the leaves due to leaf orientation, source 

directions, and leaf transmittance and reflectance values. The combination 

of these two mechanisms in the various canopies are responsible for the 

dynamics of the shifting reflectance minimum and the overall shape of 

the distributions. 

Significance to General Research Area 

• Provides hypotheses of the physical mechanisms involved in the dynamics 

of directional scattering of vegetation canopies. 

• This body of information will aid in intelligent exploitation of remote 

sensing activities that deal with directional reflectance of surfaces 

Relationship to other Fundamental Research SRAEC Investigations 

• Fundamental understanding of the directional scattering properties of 

surfaces is essential for a full scientific understanding of the earthatmosphere scene radiation complex. 

76 
Study Participants and Affiliations 

Julie Kirchner 

John Schutt 

BI'ent Holben 

Jim Tucker 

Wayne Newcomb 

Jim McMurtrey 

Dave Pinter 

Ray Jackson 

I. S. Zonneveld 

G. F. Epema 

J. de Leeun 

Numerous Gov't Officals 

77 

GSFC 

Republic Management Systems, Inc. 

Landover, MD 

Beltsville Agricultural Research Center 

Beltsville, MD 

Water Conservation Laboratory Phoenix, AZ 

International Institute for Aerial 

Survey and Earth Sciences (ITe) 

The Nether 1 il'lds 

Kasscrine, Tlmisia, Africa 
Publications (SRAEC Supported Research) 

1982 "Irradiance Measurement Errors Due to the Assumption of a Lambertian 

Reference Panel", D.S. Kimes, J.A. Kirchner, Remote Sensing of 

Environment, 12:141-149. 

1982 "Radiative Transfer MOdel for Heterogeneous 3-0 Scenes," D.S. Kimes 

and ,l.A. Kirchner, Applied Optics, 21(22):4119-4129. 

1982 "Variation of Directional Reflectnace Factors with Structural 

Changes of a Developing Alfalfa Canopy," ,l.A. Kirchner, D.S. Kimes, 

and J. E. Md1urtrey III, Applied Optics, 22:3766-3774. 

1983 "Directional Radiometric "leasurements of Row-Crop TeMperatures," 

D.S. Kimes and J.A. Kirchner, Int. J. Remote Sensing, 4(2):299-311. 

1983 "Remote SenSing of Row Crop Structure and Component Temperatures 

Using Directional Radin~etric Temperatures and Inversion Techniques," 

D.S. Kimes, Remote Sensing of Environment, 13:33-55. 

1983 "Diurnal Variations of Vegetation Canopy Structure," O.S. KiMes and 

,l.A. Kirchner, Int. J. Remote Sensing, 4(2):257-271. 

1983 "Dynamics of Directional Reflectance Factor Distributions for 

Vegetation Canopies," D.S. Kimes, Applied Optics, 22:1364-1372. 

1983 "Spectral Radiance Errors in Remote Sensing Ground Studies Due 

to Near By Objects," D.S. Kimes, J.A. Kirchner, and W.W. Newcomb, 

Applied Optics, 22:'O-IU. 

1984 "Optimal Directional View An9les for ReMotf~ SenSing Missions," 

D.S. Kimes, R.N. Holben, C.J. Tucker, and 1~.W. Newcomb, ~~ 

Remote Sensing, in press. 

l';l~N ";10rleling the Directional Reflectance from Complete Homogeneous 

Vegetation Canopies with Various Leaf Orientation Distribution," 

D.S. Kilnes, ,Journal of the Optical Society of America, in rev'jcd. 

1984 "Directional Reflectance Factor DistribLitions for Cover Types of Northern 

Africa in NOAA 7/'0 AVHRR Bands I and 2," D.S. Kimes, H.I.J. Itewcomb, 

C.J. Tucker, I.S. Zonnevelrl, W. Van Wijngaarcien, G.F. F;wlIla, and 

J. deLeelln, Remote Sensin\J of Environment, in review. 

1934 "Directional Reflectance Factor Distributions of a Cotton Row 

Crop," D.S. Kimes, W.W. Newcomb, J.B. Schutt, P.J. Pinter, Jr., 

and R.D. Jackson, Int. J. Remote Sensing, in press. 

*Note: Some of these studies were initiated before SRAEC supoort but were 

concluded with SRAEC money. 

78 

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86 
_.i' 
'--/'.' 

l" '. 

~N84 21948 

M£ASURENENT AND MODELING OF THE OPTICAL SCATTERING PROPERTIES OF CROP CANOPIES 

V; Vanderbilt and L. Grant 

INVESTIGATION SYNOPSIS 

A. Broad Goals and Investigation Objectives 

'* to measure, analyze, and mathematically model the specular, polarized, and diffuse light-scattering properties 

of several plant canopies and their component parts 

(leaves, stems, fruit, soil) as a function of view and 

illumination angles and to make available to the remote 

sensing community these data and the necessary ancillary 

data for evaluating light-canopy interaction models. 

'* to evaluate the potential of these light-scattering 

properties for ground cover discrimination and condition 

assessment. 

* to investigate these properties both in the laboratory 

and in the field and the effect on them of a disturbing 

atmosphere. 

B. First Year Obj(~ctives 

* Introduce and demonstrate the new technique for determining specular, polarized, and diffuse components of 

the reflectance factor of plant canopies. 

'* 

'* 

Measure (1) the polarized light-scattering characteristics and (2) the necessary ancillary data of plant canopies and begin preparation of data sets for use by ourselves and other investigators developing and testing 

light-canopy interaction models. 

Design and constr~ct a completely new optical instrument 

system, a portable polarization photometer capable of 

acquiring and digitally storing the data needed to determine the reflectance factor R(55,O:55,180) of a leaf 

surface 

in vivo (in the laboratory or field) 

at six wavelengths in the visible and near infrared 

at b/o polarizations 

illuminated and viewed at Brewster angle. 

87 
." 

* 

." 

* 

* 

* 

* 

Using polarization photometer, determine the mean and 

standard deviation of the polarized/diffuse/specular 

components of reflectance factor of leaves. 

3 

in a survey of plant species and varieties representing crops, forests, "weeds," and horticulture, 

including as factors (when appropriate) leaf pigmentation, development stage, position of leaf on plant, 

and position of instrument on leaf 

of a corn canopy as a function of its moisture stress 

of a greenhouse-grown wheat innoculated with wheat 

rust. 

Encourage other investigators to join in examining the 

specular/diffuse/p01arized light-scattering characteristics of leaves and plant canopies. 

Analysis of in-house polarization, sun/view angle data 

set of wheat completed. 

Polarization photometer instrument system completed. 

Survey of light-polarization properties (measured with 

polarization photometer) of individual plant leaves initiated. Twenty-two species/varieties were measured 

before frost. 

The light-polarizing properties of both moisturestressed corn leaves and diseasef wheat leaves (innoculated with wheat rust) were measured. 

Sun/view angle data plus ancillarv ~ata (necessary to 

support testing of light-canopy interaction models) were 

acquired on two wheat canopies on two ~ates and on one 

sorghum canopy on two adjacent days. 
D. Results/Scientific Findinqs 

* 

* 

* 

* 

* 

* 

Specular portion of reflected light was found to be 50% 

of the total light reflected by a wheat canopy. 

Specular and diffuse portions of leaf reflectance factor 

at Brewster angle vary significantly with species, from 

leaves being almost totally diffuse to almost totally 

specular (85% specular for corn). 

Specular portion of leaf reflectance factor is possibly 

a major source of variation -- noise -- in the reflectance of individual leaves from one species or variety. 

Leaf surface specular reflection does not depend on subsurface leaf pigmentation. 

Relative water content of moisture-stressed corn was 

found to be inversely and linearly related to the diffuse portion of the leaf reflectance factor in the red 

wavelength region. 

The severitv of wheat rust (no. of uredinia per unit 

leaf surface area) is linearly related to the specular 

portion of the leaf reflectance factor. 

E. ~nificance to General Research Area 

* 

* 

* 

* 

These results show that the leaves of many plants are 

moderately good specular reflectors. To correctly model 

the light-canopy interaction for fields of such plants, 

we mu:.t specifically consider the specular component of 

the scattered light. 

These results show there is information in the separate 

parts of the leaf reflectance -- specular (dependent on 

leaf surface properties) and diffuse (depend~nt on leaf 

bulk properties, including chlorophyll activity). 

These results suggest that a linear transformation of 

the Landsat bands might be correlated with moisture 

stress in corn and that an entirely different transformation of the Landsat bands might be correlated with 

disease infestations of rust in wheat. 

These results suggest it is virtually impossible td 

separate for most species the specular and diffuse com89 

4 
ponents of leaf reflectance usinq a Beckman DK2-type 

instrument with integrating sphere. 

F. Relationship to Other SRAEC Investigations 

* We have acqu i red wheat and sorghum data s,ets for supporting development and testing of light-canopy interaction models. 

G. Second Year Objectives 

* 

* 

* 

* 

* 

Acquire additional sun/view angle data of the polarized 

light-scattering properties of plant canopies. This 

effort will continue support for development and testing 

of light-canopy intractiion models. 

Investigate the polarized light-scattering properties of 

ground cover measured through a disturbing atmosphere. 

Collaborate with an atmospheric scientist to extend 

these results with the aio of a computer-based atmospheric model. 

Continue to search for and investigate spectral lightscattering properties indicative of canopy condition 

(such as the corn moisture content and sever i ty of whl!at 

rust) • 

Perform an AN OVA type of statistical experiment usinq 

carefully cultivated plots at the Purdue Agronomy Farm 

to investigate the potential information in specular/polarized/diffuse components of the canopy reflectance 

factor. 

Investigate more thoroughly sources of variation in specular and diffuse reflection and relate them to surface 

and anatomical features of leaf. 

* Investigate importance of Rayleigh and Mie scattering. 

* Study light-scattering properties of leaves as a function of angle. 

90 

5 
H. Study Participants and Affiliations 

V.C. Vanderbilt 

C.S.T. Daughtry 

L.L. Biehl 

L. Grant 

H. White 

D. Duncan 

G. Shaner 

1. Publ ications 

Principal Investigator 

Ph.D. Collaborator 

M.S. Collaborator 

Ph.D. Graduate Student 

Undergraduate Technician 

Und~rgraduate Programmer 

Unpaid Ph.D. Collaborator 

Vanderbilt, V.C., L. Grant, L.L. Biehl, and B.F. Robinson. Specular, diffuse and polarized light scattered by two wheat canopies. Accepted hy Applied 

Optics. 

Vanderbilt, V.C. Measuring plant canopy structure. 

Submitted to Photogrammeteric Engineering and Remote 

Sensing. 

Vanderbilt, V.C., and L. Grant. Light polarization measurements: a method to determine the specular and 

diffuse light-scattering properties of both leaves 

and plant canopies. Conference paper presented to 

the International Colloquium on Spectral Signatures 

of Objects in Remote Sensing, September 1983, Bordeaux, France. LARS Technical Report 091683. 

Grant, L., V.C. Vanderbilt, and C.S.T. Daughtry. 1983. 

Measurements of specularly reflected radiation for 

individual leaves. Agronomy Abstracts 75:12. 

Vanderbilt, V.C., L. Grant t L.L. Biehl, and B.F. Robinson. Specular and diftuse reflectance of two wheat 

canopies measured at many view angles. Abstract. 

International Union of Radio Science. January 1983. 

91 
r.... •. 

<0 

N 

REFLECTANCE MODELING 

A. Strahl er 

Hunter Coll ege 

INVESTIGATION SYNOPSIS 

~ 

A. BROAD GOALS AND INVESTIGATION OBJECTIVES 

B. 

• GENERAL UNDERSTANDING OF BRDF (BIDIRECTIONAL REFLECTANCE DISTRIBUTION FUNCTION) 

• DEVELOP AND EXTEND BRDF MODELS FOR HETEROGENEOUS CANOPIES OF 

PARTIAL COVER 

- ESPECIALLY PROCESS-ORIENTED MODELS DRIVEN BY PHYSICAL 

PARAMETERS AND MEASUREMENTS 

FIRST-YEAR OBJECTIVES 

I MODIFY INVERTIBLE CONIFEROUS FOREST CANOPY REFLECTANCE MODEL 

TO ACCOMODATE OVERLAPPING OF CROWNS AND SHADOWS 

• COLLECT AND ANALYZE PHOTOGRAPHIC DATA TO CALIBRATE TREE SPACING 

FUNCTIONS 

, CARRY OUT FIELD WORK TO PARAMETERIZE SPACING} HEIGHT} AND SHAPE 

OF CONIFERS IN OPEN AND CLOSED STANDS 

Hunter College/Strahler/1-9-84/p. 1 

~. 

~~~-

--..:;;; 

\)"\ 

~ 

-~ 

9 

~ 
C. TECHNICAL PROGRESS AND ACCOMPLISHMENTS 

D. RESULTS/SCIENTIFIC FINDINGS 

• EXTENSION OF MODEL TO MORE DENSELY STOCKED STANDS 

- DEVELOPMENT OF LINEAR APPROXIMATION TO OVERLAPPING FUNCTION 

- TESTING WITH MONTE CARLO SIMULATION MODEL SHOWS 

HIGH ACCURAC~ WITH MEANJ PROBLEMS WITH VARIANCE 

• ANALYSIS OF SPACING FUNCTION USING AIR PHOTOS 

- MANUAL DIGITIZATION OF LOCATION OF TREES IN SIX 

PLOTS REPRESENTING STANDS OF DIFFERENT DENSITIES 

- ANALYSIS OF LOCATIONS WITH RESPECT TO POINT PATTERN MODELS 

RESULTS: QUADRAT SIZES 10-50 MJ POISSON OK. AT 

SIZES )50MJ PROBABLY CLUMPED. BELOW 10 MJ TENDS 

TO UNIFORM. 

e FIELD WORK 

- DATA NEEDED TO SPECIFY SPACING FUNCTION} HEIGHT 

DISTRIBUTION J AND SHAPE OF TREES 

- CHOSE THREE STANDS REPRESENTATIVE OF REGIONAL 

CONIFER FOREST: OPEN PONDEROSA PINE; THINNED PONDEROSA PINE WITH SOME WHITE FIR; DENSE J TALL MIXED 

CONIFER W/ MUCH RED FIR 

- LAID OUT GRID OF CIRCULAR PLOTS IN EACH STAND AND 

MEASURED DBHJ TOOK HEIGHT AND SHAPE MEASUREMENTS. 

e FIELD DATA ANALYSIS -- IN PROGRESS 

- FITTING OF HEIGHTJ SPACING MODELS 

- EXAMINING EFFECTS OF THINNING J ETC. 

Hunter College/Strahler/l~9-84/p. 2 

93 

.-
<0 

..". 

E, SIGNIFICANCE TO GENERAL RESEARCH AREA 

@ PROVIDES DIRECT SUPPORT FOR SCENE ANALYSIS~ FORESTRY APPLICATIONJ OTHER 

MODELING EFFORTS AND MEASUREMENT PROGRAMS 

* SUPPORTS PREDICTION OF OPTICAL-REFLECTIVE RESPONSES OF VEGETATION 

CANOPIES 

F, RELATION TO OTHER FUNDAMENTAL SRAEC INVESTIGATORS 

~ DIRECTLY RELATED TO; AND COORDINATED WITH;SMITHJ NORMAN 

, COULD INCORPORATE/RELATE TO WORK BY TUCKER; VANDERBILTJ MOORE 

G. SECOND-YEAR OBJECTIVES 

, EXTEND INVERTIBILITY TO OVERLAPPING CASE 

8 DEVELOP MODEL/PARAMETERS FOR SPACING FUNCTIONJ HEIGHT DISTRIBUTIONJ 

CANOPY FORM 

o CONTINUE MONTE CARLO SIMULATIONS; EXTEND TO FULL THREE DIMENSIONS 

i ASSEMBLE J REGISTER MULTI IMAGE DATASET FOR TEST AREA 

- TM SIMULATOR (30 MJ 7 BAND) 

- LANDSAT 4 MSS (50 MJ 4 BAND) 

- SPOT SIMULATOR (10 M; 3 BAND) 

- JPL AIS (30 MJ 128 BAND) 

- DTM (30 M; OPTICAL CORRELATOR) 

Hunter College/Strahler/1-9-84/p. 3 
...,."."..,.. .. 

H. STUDY PARTICIPANTS AND AFFILIATIONS 

~ GRADUATE STUDENTS -- UCSB 

- CURTIS E. WOODCOCK (PH.D EXP. 1984) 

- XIAOWEN LI (PH.D Exp. 1985) 

- JANET FRANKLIN (MA J 1983) 

, COLLABORATORS 

- D. S. SIMONETT) UCSB (SUBCONTRACT) 

- J. A. SMITH) CSU 

- J. M. NORMAN) U. NEB. 

I, PUBLICATIONS 

~ THESES: 

FRANKLIN) JANET) 1983) AN EMP!RICAL STUDY OF THE SPATIAL PATTERN OF 

CONIFEROUS TREES. M.A. THESIS) UNIV, OF CALIF.) SANTA BARBARA 

MANUSCRIPTS IN PROGRESS: 

FRANKLIN) J.) J. MICHAELSON) AND A. STRAHLER) A COMPARISON OF STATISTICAL METHODS FOR MEASURING SCALE DEPENDENT PATTERN IN FOREST 

STANDS. IN SECOND DRAFT. 

STRAHLER) A.) AND X. LI) SPATIAL/SPECTRAL MODELING OF DISCONTINUOUS 

CONIFER STANDS. FIRST DRAFT ABOUT HALF COMPLETE. 

Hunter Col1ege/Strahler/1-9-84/p. 4 

, ' 

.. I' 

~ 

, . 

I., 

~ "Ii84 21949 

A STUDY OF THE RELATION BETWEEN CROP GROWTH 

AND SPECTRA REF~ECTANCE PARAMETERS 

14dlL H'\ 

INVESTIGATION SYNOPSIS 

G. Badhwar 

NASAjJSC 

A. BROAD GOALS AND INVESTIGATION OBJECTIVES 

o To INVESTIGATE THE DYNAMIC BEHAVIOR OF CANOPY REFLECTANCE VERSUS 

TIME AND THE RELATIONSHIP THAT SUCH TRAJECTORIES BEAR TO CANOPY 

DYNAMICS J FOR EXAMPLE J ONTOGENY AND MORPHOLOGY· 

o To UNDERSTAND WHICH TRANSFORMATIONS OF SPECTRAL DATA ARE BEST 

SUITED FOR OBSERVING KEY CANOPY CHARACTERISTICS J SUCH AS LEAF AREA 

INDEX AND VEGETATION IDENTIFICATION· 

o To FORMULATE A PHYSICAL BASIS FOR UNDERSTANDING HOW VARIOUS SPECTRAL TRANSFORM TRAJECTORIES DEPEND ON VEGETATION TYPE AND FORMULATE 

MODELS THAT DESCRI BE THE TIME DELAYED INTERACTION OF REFLECTANCE 

IN THE CHLOROPHYLL AND WATER ABSORPTION BANDS TO MONITOR STRESS. 

o As PART OF THE GENERAL PROCESS OF PHYSICAL UNDERSTANDING OF CANOPY 

REFLECTANCE J EVALUATE AND IMPROVE EXISTING CANOPY MODELS· 

B. FIRST YEAR OBJECTIVES 

o To INVESTIGATE THE DYNAMIC BEHAVIOUR OF CANOPY REFLECTANCE VERSUS 

TIME AND THE RELATIONSHIP THAT SUCH TRAJECTORIES BEAR TO CANOPY 

DYNAMICS J FOR EXAMPLE J ONTOGENY AND MORPHOLOGY· 

o To FORMULATE PHYSICAL BASIS FOR UNDERSTANDING HOW VARIOUS SPECTRAL 

TRANSFORM TRAJECTORIES DEPEND ON VEGETATION TYPE· 

96 

I 
\ 

C. T ECHN I CAL PROGRESS AND Accor~PLI SHr-1ENT 

o A DIFFERENTIAL EQUATION DESCRI RING THE TEr1PORAL BEHAVIOR OF GREENNESS WITH TIME WAS DEVELOPED AND SHo\~N TO F IT THE OPSERVATIONS VERY 

WELL· 

o IT PROVIDED: 

- A TECHNIQUE TO ESTIMATE LEAF AREA INDEX 

- A WAY TO ESTIMATE KEY ONTOGENIC STAGE OF CROPS 

- PARAMETERS TO IDENTIFY AND SEPARATE VARIOUS CROPS 

o THESE PARAMETERS WERE SHOWN TO BE STABLE OVER VAST AREA OF UNITED 

STATES AND FOR THE FIRST TIME OVER A FOREIGN COUNTRY (ARGENTINA). 

o SCATTERING BY ARBITRARI LY INCLINED LEAVES (SAIL> MAULTI LAYER MODEL 

WAS IMPLEMENTED AND TESTED OVER CORN AND SOYBEAN CROPS. 

o SERIOUS LIMITATION OF SUITS J SAIL AND CUPID MODEL OVER THESE DATA 

SETS HAVE BEEN FOUND· IMPROVEMENTS HAVE BEEN SUGGESTED· 

D. RESULTS/SCIENTIFIC FINDINGS 

o DYNAMIC BEHAVIOR OF GREENNESS J G(T)J IS DESCRIBED BY 

D6(T) ~ K(T) (1- G ) m GM 

WHERE GM IS THE MAXIMUM GREENNESS AT TIME Tp. 

o IT HAS BEEN DEMONSTRATED THAT K(T) OBEYS THE LAW 

K(T) ~ 2 [lIT + l/Tp-Tl T<Tp /' 

o AND I K(T)DT IS LINEARLY PROPORTIONAL TO LEAF AREA INDEX .J 

o MAXIMUM GREENNESS J GMJ TIME OF MAXIMUM GREENNESS J TpJ AND PROFILE 

WIDTH, cr., ARE THE KEY VARIABLE THAT RETAIN NEARLY ALL THE INFORt-'1-

ATION IN RAW CHANNELS ARE STABLE OVER VAST GEOGRAPHIC AREAS J AND 

ARE PREDICATABLE· 

o THE TIME OF PEAK AND INFLECTION CAN PROVIDE KEY ONTOGENIC STAGES· 

97 
• U' 

E. SIGNIFICANCE TO GENERAL RESEARCH AREA 

o BIOPHYSICAL CHARACTERISTICS ESTIMATION 

o OPTICAL MODELING OF CANOPY REFLECTANCE. 

F. RELATIONSHIP TO OTHER FUNDAMENTAL RESEARCH INVESTIGATIONS 

o PROVIDES KEY INPUT TO OPTICAL REFLECTANCE MODELING. 

o PROVIDES INTERPRETATION OF REFLECTANCE· 

o DERIVED PARAMETER GW Tp AND O"HAVE FOUND THERE WAY IN 

MANY FUNDAMENTAL RESEARCH INVESTIGATIONS OF MPRIA. 

G. SECOND YEAR OBJECTIVES 

o VERIFY THE VALIDITY OF CANOPY REFLECTANCE MODELS AND MODIFY THEM 

TO CORRECT FOR DEFICIENCIES. 

o UNDERSTAND WHY THE PEAK GREENNESS FOR SOYBEAN IS GREATER THAN FOR 

CORN USING THESE MODELS? ARE THERE CONDITIONS UNDER WHICH THIS 

IS NOT VALID? 

o MATHEMATICALLY FORMULATE THE KEY PROBLEM OF FINDING OPTIMUM TRANSFORr~ATIONS~ RASED ON VERIFIED CANOPY MODELS, THAT MAXIMIZE THE 

SENS ITIVITY TO LEAF AREA INDEX AND MINIMIZE SENS IT IVITY TO ALL 

THE OTHER VARIABLES. 

o ApPLY THESE TRANSFORMATIONS TO WHEAT, BARLEY, OATS, CORN AND SOyBEAN CROPS· 

H. STUDY PARTICIPANTS 

1. JERRY KRANTZ 

2. MARY ANN TOMPKINS 

3. LYNNE ALEXANDER 

4. DR· SYLIVA SHEN 

ALL OF LOCKHEED MSCO J HOUSTON, TEXAS 77058 

98 

, 
I. PUBLICATIONS 

BADHI'IAR, G. D., (984): AUTOMATIC CLASS IF ICATION OF CORN AND SOYBEAN 

USING LANDSAT DATA: PART I: NEAR-HARVEST CROP PROPORTION tSTlMATION. 

REMOTE SENS ING OF ENVIRONMENT) FEBRUARY (1984) 

BADHWAR, G. D. , (1984): AUTOMATIC CLASSIFICATION OF CORN AND SOYBEAN 

USING LANDSAT DATA: PART II: EARLy-SEASON CROP PROPORTION ESTIMATION. 

REMOTE SENSING OF ENYIRONMENT, FEBRUARY (19S4) 

HENDERSON, K. E. AND G. D. BADl-MAR (984): AN INITIAL MODEL FOR ESTIMATING DEVELOPMENT STAGES FROM SPECTRAL DATA. RH10TE SENSING OF t.NVIRONMENT, FEBRUARY 09S4) 

G. D. BADHWAR (984) - USE OF LANDSAT-DERIVED PROF I LE FEATURES FOR 

SPR I NG SMALL GRAI NS CLASS IF I CATION, INTERNATIONAL JOURNAL OF REMOTE 

SENSING, (1984) 

D. HELMER, J. KRANTZ, M. TotJlPKINS, AND G. D. BADHWAR (1983) - USER 

GUIDE FOR THE EXTRACTION OF LANDSAT SPECTRAL AND AGRONOMIC DATA, 

AGRISTARS DOCUMENT JSC-1859S 

D. HELMER, J. KRANTZ, M. KINSLER, M. TOMPKINS, AND G. D. BADHWAR (1983) 

COMPOSITION AND ASSEMBLY OF A SPECTRAL AND AGRONOMIC DATA BASE FOR 1980 

SPRING SMALL GRAIN SEGMENTS, AGRISTARS DOCUMENT JSC-18593 

D. HELMER, J. KRANTZ, M. KINSLER, M. TOMPKINS, AND G. D. BADHWAR (1983) 

ARGENTINA SPECTRAL DATA BASE, AGfUSTARS DOCUt1ENT 

LYNNE ALEXANDER AND G. D. BADHWAR (983). - SAIL CANOPY MODEL FORTRAN 

SOFTWARE, LEMSCO-19867 

99 

I 
-, 

.. 

""Vl"i!p ',- - .,;;:$ b «<*'*'4 .& -t-:~.t1f'i-.? :1;\..5: ?;~l~t r}!ifP ~'",f~:lIY~¥:WO· :qSJJPIi& a .... ,·:;;:;Ji($2ift# .. ,W.- '\j'W;;;h,y:,~.q~'¥.t:~~~W;W''''"''?~1jb@·'!ft''i,f'l¥qi';.V$r1'??i_"~'mt':V,,!,!i~,;,"~ 'Pi;. ::S~&"';"'4 r"t't.1ih .... :v.;:;:,'t .ihl~'*\~~%;~-0-i'-:'~~~:n::~~l 

MODEL 

o Models indicate that: 

+ The dominant contributor to the reflective 

signal is leaves 

+ The Key parameter is the I.eaf area index (one-sided 

leaf area) 

o K(t): Time rate of change of LAI 

o dp ( +) = K( t)p (1 P ( + ) ) 

dt Pm 

P = greenness 

Pm = maximum value of greenness attained at time 

t=tp 

o 5 1« t ldt 0(. Leaf Area Index 

00 

"'11;:0 

"'O~ Oz 

OJ;3 

::01-

0-0 

c:..., 

:r-- :'") [: ;·1 

_.I.-t'I' 

.~ \..~~ 
l~) 

G 

R 

4e~ 

E _ 

E 30-

N -

N 

E 

S 

S 

R 

E 

F 

L 

- 20-

E _ 

C 10-

T 

A 

N 

C 

E 

4 

i 

~~ o 0 

~ 

(:11 0 

1;./11, i I I I r I n lit f , rr I r-f 1" ttM ft '1 Jf"TTf f If I I ' r HI fJ ff l' r r H If I 'I r II r "r If I' r H , rr " I ' II " " " I II , , , .. " J 

o 20 40 60 80 t00 120 140 t60 f80 200 

DAYS SINCE PLANTING 

PLOTS 1A WHEAT (A~IZ0NA) 

'\ ~ 

00 

":::0 

"tJ~ 

07-

O):D 

;Or-

.0"0 

c:;;, 

;:t>G"J 

'-1'1 

::f .... -< r/ .. 

, 

( 
, 

ff14 ,4 

~ 

;':. 

F 

U 

0.S..l .., 

i ... 

r:t .~_ 

V. t 

""1 

N ~3.~lC 

T 

I 

o e. ~~­

N 

K ... 

T 0.1-

~ 

//' 

YODEL = (TP(2.j(TP-T»)VT 

~ 

1 

., 

~".. - a:;JJ 

e. ~)-i ""j"1,-,r-,rTl ~I rt-r-rt n T f f rt ' 'f' ' f t I ' , t , t ' , , t t ' i , t t t t t t r f , t ,. r t t f , t t t , t , t t ,t t f' , " ' t t 'fTT'"T 

o 5 Ie 15 20 25 30 35 43 45 50 55 69 65 70 75 

DAYS 8EFORE PEAK 

PLOTS 1A WHEATCARIZONA) Gi~AXT = t 1 e. 5 GMAX = 32. t 975 R-SQUARE = 0.989748 

00 

"T1:::il 

.,,5 

0-

o~ ::01'"": 

01:J C::;:.. 

~G") 

r- :1'1 

::; ..... ..(~ 

1 .. 
... ~ 

(") 

'" 

........ 

L 

E 

A 

F 

61 

-l I 

.. i 

-; 

I 5-, 

"'1 

..J 

i 

"1 

... 

4-1 

-; 

j A j 

R 3-1 E -i 

A ~ .~ 

I 2~ I N 1 

D 1 ~ 1 I.. .. 

X t-i 

o 

o 

o 0 

o 

·,.'.~ 

0 0 

0 

o 

o 

o 

o 

o 

1 0 0 0 

aJfT •••••••• , ••••••••• ! ••••••••• , ••••••••• , ••••••••• ! ••••••••• 1 

2 3 4 5 6 7 8 

INTEGRAL KT 

DAY3 BEFORE FEAK 

PLOTS 18 WHEAT (ARIZONA) . GMAXT = 105.!J MAX = 185 80 = 0.1169147 81 =-2 52 = 9.978696 .. _....... -- - ----

OD 

'-r: :~J 

'l; -..) 

o a,"; 1"- .... 

~~ ~-:~ 

(0 ":1 ::, '~ .. 

t .~:-~.:. 

.... ' .... 1 rl! i:.; 

4" .. 
>-' 

0 

.r--.. 

(:~l 

GMAX 

6000 

5000 

1* ! 

400e~ 

~ 

3eee~ 

2000 

* 

CORN SOYBEAN 

** 

If ~. * ~,~, ~,~: * :~ ... " "~.I~* :l " .1-

~., ... ~' :' .. 7 * * *'~;*"" ~-I' * * ~ ll"~ 1*; :t~I}t * * 

*** ** * :} 

: * lie ** 

* * + + 

* ~ * 

+. + + + 

+ -q. \ft+ +~++ ¥ ++ + + !.J:!..'Fit;"+t++.'" 

~"-~.'! ." i:T 4- + ~q-r . IV'.,- "'-1+ 

+ + ift+.l::t + + * l i- + * + 

1 0eeL .................................................................................... . 

4130 500 600 700 800 900 1000 lf00 1200 1300 

SIGMA 

LEGEND: GTLAB + + + t * * * 2 

00 

."f'l ::a 

"'ilQ 

0

°2 ;1:, ~ j.: 

tO~ c: .. , ;C .. I~" r.":'i 

::; "#~'I ~i.-;j 

.. f" 

• 

-, 

~ 

C" 

~ 

,.. 

f-

..... 

~ 

, 
III.C.2. SCENE RADIATION STUOIES·MICROWAVE REGIME 

A. Fung Scattering r10dels in the Microwave Regime 

J. Kong Remote Sensing of Earth Terrain 

R. Lang Discrete Random Media Techniques for Microwave riodellng of 

Vegetated Terrain 

F. Ulaby - Measuring and Modeling of the Dielectric Properties and Attenuation 

of Vegetation 

R. Moore . Determination of the Sources of Radar Scattering 

J. Paris - Microwave Backscattering Properties of Crops 

105 

.... N84 21950 

SCATTERING MODELS INg.}~~ MICROWAVE REGIME \ 

1t~'1J.,F ( .(, r r~_>, V-/l..( h 

1\. ung \1 A), \ \]v 

U. of Kansas IN \ 

INVESTIGATION SYNOPSIS 

oTO DEVELUP ~CATTERING MODELS FOR AN 

INHOMOGENEOUS MEDIUM~ 

~ TO D~Vr:l.OP SCATTERING MODELS FOR AN 

IRREGULAR SURFACE. 

~ TO COMBINE VOLUME AND SURFACE SCATTERING 

TO OBTA~N USEFUL SCATTERING AND EMISSION 

MODelS FOR TERRAINS • 

• 'TO APrlY THE DEVELQPED MODEL TO THE 

INTERPRETATION OF ~EASURED DATA AND THE 

DESIGN OF FUTURE EXPERIMENTS. 

IOn 
-. \ 

b. FIRST YEAR OBJECTIVES 

• DEVELOP 1\ TERRAIN SCI\TTERING MODEL BY 

COMBINING VOLUME SCATTERING (DUE TO 

VEGETATION OR SNOW, ETC.) WITH ROUGH 

SURFACE SCATTERING (DUE TO ROUGH GROUND 

SURFACE). 

c. TECHNICAL PROGRESS AND ACCOMPLISHMENTS 

-TERRAIN SCATTERING MODELS HAVE BEEN 

DEVELOPED USING THE RADIATIVE TRANSFER 

METHOD WHICH MAY BE A~PLICABLE TO A SNOW 

LAYER OR A VEGETATION LAYER WITH IRREGULAR BOUNDARIES. 

107 

3 
~AL PAGE 19 

Of. POOR QUALiTY 

d. RESULTS/SCIENTIFIC FINDINGS 

OIN SCATTERING FROM AN INHOMOGENEOUS LAYER 

. WITH IRREGULAR BOUNDARIES IT IS FOUND: 

(!: ROUGH SURFACE SCATTER~~G IS IMPORT/.K:- ,M:: NEAx VEir:ICAL OBSERVATIONS 

AND HAS THE ~Fr~S~ :: ENH~~CING 

CRO~S-POLAR!ZEr S:A:TERJ~G. 

\2) VOLUME SCATTERING FRO~ LAYER I~-

HOMOGENEITIES DOMINATES SCA:TERING 

(LIKE AND CRJS~) A"': L/.lRGE H'CIDENCE 

ANGLES. 

(3) THE MECrlANISM J~ CROSS-POLARIZED 

SCATTERING IS ~lULTIPLE SURFA.CE/ 

VOLUME SCATTERINGo 

lOS 

4 
I 

! 

i 

ORIGiNAL PAGE IS 

OF POOR QUALITY 

e. SIGNrFtCANCE TO GENERAL RESEARCH AREA 

• IN THE PAST) ROUGH SURFACE SCATTERING AND 

VOLUME SCATTERING WERE TREATED INDEPENDENTl.Y AS TWO SEPARATE FIELDS OF STUDY. 

THIS RESEARCH COMBINES THE TECHNIQUES IN 

THE Tl-JO AREAS 7,) P~OVIDf A MORE REALISTIC 

TERRAIN SCATTERING MODEL A~D PERMITS THE 

STUDY OF THE INTERACTION BETWEEN SURFACE 

AND VOLU~'E SCf,TTERING. 

109 

, 

5 
• 

6 " '. . 

f. RELAT:ONSHIP TO OTHER FUNDAMENTAL RESEARCH 

SRAEC INVESTIGATIONS 

RESULTS OF THIS RESEARCH ARE USEFUL FOR 

UNDERSTI'.NDING EXPERIMENT.~L OBSERVATIONS 

OF WAVE SCATTERING FROM TERRA'~NS AND 

PROVIDE INPUT TO THE DESIGN OF FUTURE 

EXPERIMENTS ON TERRAIN SCATTERING. 

110 
. , 

\. 

i 

, 

l 

g. SECOND YEAR OBJECTIVES 

ORK*Nl~L PAC'!! i~ 

OF. P00P Q! I.(\,-"T-" 

_DEVELOP A SCATTERING MODEL FOR A LAYER OF 

RANDOMLY ORIENTED CIRCULAR DISCS WITH 

RADII COMPARABLE TO THE ELECTROMAGNETIC 

WAVELENGTH. USE THIS MODEL Te INVESTIGATE THE RELATIVE MERI7S BETWEEN ACTIVE 

VERSUS PASSIVE SENSING O~ SO~L MCISTCRE 

OVER VEGETATION-COVERED SOIL SUPFACES. 

h. STUDY PARTICIPANTS 

M. KARAM, GRADUATE STUDENT 

G. W .. PAN, GRADUATE STUDENT 

H~ J. EJM, RESEARCH ASSOCIATE 

111 

, 

7 
8 

• 

i. PUBLICATIONS (SRAEC SUPPORTED RESEARCH) 

Fung, A. K. and H. J. Eom, "Effect s of a Rough 

80undary Surface on Polariz~tion of the 

Scattered Field from an Jnhomogeneous 

~1edium," IEEE Geoscience and Remote 

Sensi~, (IGARSS I82), vol. AP-21, no. 3, 

pp. 265-270, C~ly Jf93. 

Karam, M. and A. K. ~U'10, "<;cat';:e:"'i ng from 

Randomly Orientel ~ircular Discs wit~ 

Al')plication to '.'egetatior.," Radio . .. ... --

Scie~~~, vol. 18, no. 4, pro 557-565, 

July-Au~ust :983 • 

.... 112 
ORIGJNAL PAGE IS 

OF POOR QUALITY 

Karam, M. and A. K. Fung, "Scattering from Rancomly Ori entet1 Scat terers 0f Arbi t rary 

Shape in the Low-Frequency Limit with 

Application to Vegetatiot"l," Dig~st-2f. 

19~RS~Ql, IEEF. 1983 International 

~eosc~ ~nce (I"d qemot.p Sensi ng Sympos ium, 

p,l.'gust 19H3. 

Fung, A. K. and ~I • .J, :r.m, lI~cdtt.er';ng from a 

Random Layer ''Ii ',',h Apr 1; rQt in:. to SnO\v, 

Vegetation and Sei) Ice," l~E J..r9ceedil]ll~ 

_':"2pecial l.llsue 9L8.9dLowave Propagation, 

U'.ccepted) • 

Fung, A. K. and H. \J. Eorn, "A Scatter r·~odel f0r 

Ve~E.;.:~:.til)n up to Ku-Band," Remote Sensing 

,of En-Y.l! .. :g.!}~QD.t., (Accepted). 

113 

9 
ORIGINAL PAG~7 ~~:' 

OF POOH QUALITY 

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REMOTE SENSING OK EARTH TERRAIN ~I ,~\V\ • 

J. Kong) • 

M. I. T. ttJlil'I..~~ -~~_ 

21951 

BROAD GOALS Am> INVESTIGATION OBJECTIVES 

~.n. tc Ce. i. hnt.t.:...) 

* Development of theoretical models for remote sensing of Earth terrain 

* Data analysis and interpretation using the models developed 

* Scene simulation 

* Development of new remote sensing approaches and techniques 

FIRST YEAR OBJECTIVES 

* Development of numerous theoretical models that are applicable to the 

active and passive remote sensing of 

plowed fields 

atmospheric precipitation 

- vegetation 

- snow fields 

* Data interpretation 

122 
\' 

." Continue development of theoretlcal models 

Multi-layered model to investigate the effect of ice layers in the 

snowfields 

Study scattering of waves from a layer of densely distributed 

dielec:trical scatterers on top of homogeneous halfspace using the 

quantum mechanical potential approach 

." Document all the computer programs for the theoretical models developed 

." Start image simulation studies 

123 
Under the support of the fundamental research program, we have completed 

eight journal articles, six conference articles, and on~ technical "report. In 

summary, we have: (1) solved the problem of microwave scattering from 

periodic surfaces using a rigorous modal technique; (2) studied scatteriog of 

electromagnetic waves from a randomly perturbed quasi-periodic surface with 

Kirchhoff approlcimation; (3) studied the combined random rough surface and 

volume scattering effects; (4) investigated the anisotropic effects of 

vegetation structures; (5) studied passive and active remote sensing of 

atmospheric precipitation with the vector radiative transfer equations; (6) 

studied the scattering of a plane wave obliquely incident on a half space of 

densely distributed spherical dielectric scatterers with quantum mechanical 

potential approach; and (7) applied the strong fluctuation theory to the 

study of electromagnetic wave scattering from a layer of random discrete 

scatterers. 

The problem of microwave scattering from periodic surfaces is solved by 

using a rigorous modal technique which conserves energy, obeys reciprocity, 

and takes into account the multiple scattering and shadowing effects. The 

theoretical results have been applied to the calculation of the radar 

backscatterlng cross sections in active remote sensing and the brightness 

temperatures in passive remote senSing, and used to match field data from soil 

moisture measurements. The angular behavior of the brightness temperatures 

has been explained wi.th the threshold phenomenon by considering the appearance 

and disappearance of the various Floquet modes. 

124 
The Kirchhoff approximation is used to study the scattering of 

electromagnetic waves from a randomly perturbed quasi-periodIc surface. In 

order to more realistically model the plowed fields the rough surface is 

characterized as a composite surface with a Gaussian random variation, a 

sinusoidal variation and a narrow-band Gaussian random variation around the 

same spatial frequency. In the plowed fields there are some random variations 

on the period and amplitude of the sinusoidal variation as we move from one 

row to the next. This variation can be modelled by introducing the 

narrow-band Guassian random process on top of the basic sinusoidal variations, 

which will cause the surface to be quasi-periodic. The scattering 

coefficients can be interpreted as a convolution of the scattering patterns 

for the sinusoidal and the random rough surfaces. For the backscattering 

cross sections we observe the occurrence of peaks whose relative magnitudes 

and the locations ar.e explained in terms of the scattering patterns for 

sinusoidal surfaces. 

The ._ ,&bined random rough surface and volume scattering effects have 

been studied by employing a Gaus&ian random surface and applying the small 

perturbation methods which is modified with the use of cumulant techniques. 

The rough surface effects are incorporated into the radiative transfer 

equation~ by modifying the boundary conditions for the intensities. The 

radiative transfer equations are then solved numerically using the Gaussian 

quadrature method and the results are illustrated and compared with 

experimental data. 

The anisotropic effects of vegetation structures are investigated and the 

theoretical results are used to match experimental data. The azimuthally 

anisotropic behavior of the measurement result is attributed to the 

orientations of the vegetation stalks which were laid on the ground during the 

125 
field measurements. The effect of the soil moisture on the brightness 

temperature measurements from the wet and dry corn stalks has been clearly 

identified. 

Both passive and active remote sensing of atmospheric precipitation are 

studied with the vector radiative transfer equations by making use of the Mie 

scattering phase functions and incorporating the rain drop size distributions. 

For passive remota sensing we employ the Gaussian quadrature method to solve 

for the brightness temperatures, and for active remote sensing an iterative 

approach carrying out to second order in albedo is used to calculate for the 

bistatic scattering coefficients and the backscattering cross sections per 

unit volume. 

The scattering of a plane wave obliquely incident on a half space of 

densely distributed spherical dielectric scatterers is studied with quantum 

mechanical potential approach. The quasi-crystalline approximation is applied 

to truncate the hierarchy of multiple scattering equations and Percus-Yevick 

result is used to represent the pair distribution function. nhile results at 

high frequencies are calculated numerically, closed form solution are obtained 

in the low frequency limit for the effe~~ive propatation constants, the 

coherent reflected wave and the bistatic scattering coefficients. 

The strong fluctuation theory is applied to the study of electromagnetic 

wave scattering from a layer of random discrete scattcrers. The singularity 

of the dyadic Gre~n's function is taken into account in the calculation of the 

effective permittivity functions. The correlation functions for the random 

medium with different scatterer constituents and size distributions are 

derived. Applying the dyadic Green's function for a two layer medium and 

using the bilocal and distorted Born approximations, the first and the second 

moments of the fields are calculated. 

12(; 
Academic and Research Staff 

Professor J. A. Kong: Principal Investigator 

Dr. L. Tsang 

Dr. S. L. Chuang 

Graduate Students 

Y. Q. Jln S. Lin 

J. K. Lee R. T. Shin 

127 
PUBLICATIONS 

A. Journal Articles 

1. S. L. Chuang and J. A. Kong, "Wave scattering and guidance by dielectric 

waveguides with periodic surface," Journal of the Optical Society of 

America, vol. 73, no. 5, 669-679, May 1983. 

2. Y. Q. Jin and J. A. Kong, "Passive and active remote sensing of 

atmospheric precipitation," AEplied Optics, vol. 22, 2535-2545, Sept. 

1983. 

3. L. Tsang and J. A. Kong, "Scattering of electromagnetic waves from a half 

space of densely distributed dielectric scatterers." Radio Science, vol. 

18, no. 6, 1260-1272. Nov.-Dec. 1983. 

4. J. A. Kong, S. Lin, and S. L. Chuang, "Thermal microwave emission of 

periodic surface," IEEE Transactions on Geoscience and Remote Sensing, to 

be published. 

5. R. T. Shin and J. A. Kong, "Scattering of electromagnetic waves from a 

randomly perturbed quasi-periodic surface," Journal of Ap£~ied Physics, 

to be published. 

6. J. K. Lee and J. A. Kong, "Dyadic Green's functions for layered 

anisotropic medium," Electromagnetics, to be published. 

7. L. Tsang, J. A. Kong, and R. T. Shin, "Radiative transfer theory for 

active remote sensing of a layer of nonspherica1 particles," Radio 

Science, ro be published. 

8. Y. Q. Jin and J. A. Kong, ·Strong fluctuation theory for electromagnetic 

wave scattering by a layer of random discrete scatterers," Journal of 

Applied Physics, to be published. 

B. Conference Articles 

9. J. A. Kong, "Theoretical models for microwave remote sensing of 

vegetation and soil moisture," AgRISTARS S;l!l1!.:?.~, Houston, Texas, 

December 1-2, 1982. 

10. J. A. Kong, S. L. Lin, S. L. Chuang, Bnd R. T. Shin, "Remote sensing of 

soil moisture and vegetation. URSI SymeOS!\lffi, Boulder. Colorado, January 

5-7, 1983. 

12[, 
11. R. T. Shin and J. A. Kong. "Thermal microwave emission from a scattering 

medium with rough surfaces." URSI Srmposium. Boulder. Colorado. January 

5-7. 1983. 

12. Y. Q. Jill and J. A. Kong. "Mie scattering of electromagnetic waves by 

precipitation." Qptical Society of America Topical Meeting on Optical 

Techniques for ~~mote Pt'obin!:) of the Atmosphere." Lake Tahoe. Nevada. 

January 10-12. 1983. 

13. L. Tsang and J. A. Kong, "Scattering of electromagnetic waves from a 

half-space of densely distributed dielectric scatterers. IEEE/APS 

Sl!!posium arid URSI Meeting. Houston, Texas, May 23-26, 1983. 

14. L. Tsang and J. A. Kong, "Theory of microwave remote sensing of dense 

medium," IEEE/GR~ Symposium and URSI Mcetln..a. San FranciSCO, September 

1983. 

C. Technical Reports 

15. R. T. Shin and J. A. Kong, "Emissivity of a two-layer random medium with 

anisotropic correlation function." Technical Report No. EWT-RS-41-8303. 

MIT. 1983. 

129 
It!Y VISUAL AIDS 

!.igure 1 

Figure 2 

!.igure 3 

!.igure 4 

Figure 5 

Figure 6 

Figure 7 

Figure 8 

!.igure 9 

!.igure 10 

~ure 11 

Figure Captions 

Geometrical configuration of the problem for wave scattering from 

sinusoidal surfaces. 

Brightness temperatures as a function of viewing angle for both the 

vertical and horizontal polarizations as compared with experimental 

data. Radiometer observation plane is parallel to the row 

direction. 

Brightness temperatures as a function of viewing angle for both the 

vertical and horizontal polarizations as compared with experimental 

data. Radiometer observation plane is perpendicular to the row 

direction. 

Brightness temperatures as a function of viewing angle for both the 

vertical and horizontal polarizations as compared with experimental 

data. Radiometer observation plane is not parallel to the row 

direction. 

Geometrical configuration of the problem for wave scattering from 

two"layer random discrete scatterers. 

Brightness temperature versus rain rate at 19.35 GHz. 

Horizontally polarized backscattering cross sections versus 

frequency for dry snow. Ice radius • 0.7 rom, fractional volume B 

0.25. 

Horizontally polarized backscattering cross sections versus 

frequency for wet snow. Water drop radius - 0.4 rom, fractional 

volume ~ 0.02, ice radius = 0.7 rom, fractional volume - 0.23. 

Horizontally polarized backscattering c:oss sections versus snow 

wetness. Hater drop radius" 0.4 mm, ice radius" 0.7 mm, total 

particle fractional volume • 0.2. 

Backscattering cross sections versus frequency for snowpack. 

Depolarized backscattering cross sections versus frequency for 

snowpack. 

130 
Firun:e 12 Reflectivity versus snowfall rate at 9.375 GHz. 

Fil3ure 13 Reflectivity versus snowfall rate at 9.375 GHz. 

Fisure 14 Snowfall attenuation versus snow mass concentration at 95 GHz. 

Fisure 15 Snowfall attenuation versus snl)w mass concentration at 140 GHz. 

Fisure 16 Snowfall attenuation versus snow mass concentration at 217 GHz. 

131 

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9.375 GHz 

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I 
A. 

,. N84 21952 

DISCRETE RANDOM MEDIA TECHNIQUES FOR MICROl4AVE MODELING 

OF VEGET~\E~\ !ERRAIN 

Rf.;1~l (j )z rt (c ,- ·i (( <. CL L • 

- ang \-\....41' ('.(l v,. 

Geo. Wash. Unfv •. 9 (c L .. "':1"'1 I" "( !IIJ,/ ~ ':7 etc. "'(.( 

BROAD GOALS AND INVESTIGATION OBJECTIVES 

-Use discrete scatter theory to model vegetation (crops and 

forested regions) in microwave region. 

-Develop models for scatterers and ground. 

"Multiple scattering analysis-relate model parameters to 

average scattered power. 

-Develop inversion techniques to remotely determine model parameters. 

B. FIRST YEAR OBJECTIVES 

-Develop models for discs, stems and trunks. 

oDerive coherent and incoherent distorted Born approximation 

(DBA) for resonant scatterers. 

'Account for rough ground surface. 

oModel mature soybean crop. 

C. TECHNICAL PROGESS AND ACCOMPLISHMENTS 

-Scattering models developed for electrically thin and thick 

discs, thin stems and infinite trunks. 

oBackscattering coefficients computed by coherent and incoherent 

DBA for: 

(i) slab geometry (ii) thin discs and thin stems 

(iii) Rician rough surface 

oBackscattering coefficients decomposed naturally into direct, 

direct-reflected and reflected components. 

-Theoretical and experimental results compared for mature soybean 

crop in lower GHz region. 

14B 
O. RESULTS/SCIENTIFIC FINDING 

-Coherent and incoherent DBA results are close for like polarizations-differ substantially for cross polarizatior. 

-Theory used to model mature soybean crop in 1-4 GHz region. 

Findings are: 

(i) For HH polarization- leaves more important 

than stems at all angles. 

(ii) For VV polarization- stems more important than leaves at large angles of incident. 

(iii) Rough surface effects are dominant at 

angles less than 15°. 

(iv) Direct-reflected contributions more important than direct contributions for most 

ground moistures. 

-Good agreement obtained between Ulbaly. et al. (IEEE-GE, 1979) 

soybean data and theory at 1.5 GHz. 

E. SIGNIFICANCE TO GENERAL RESEARCH AREA 

-Discrete scatter DBA method provides a good vegetation modeling technique in the lower microwave region (1-4GHz). 

-Isolates dominant scatter types within the canopy. 

-Can be used to develop crop classification techniques. 

-Ground moisture can be related to backscattered power. 

F. RELATIONSHIP TO OTHER FUNDM1ENTAL RESEARCH SRAEC INVESTIGATIONS 

-Kong- uses predominantly continuous random medium modeling. - lately emphasizing dense media (snow.). 

-Fung- Incoherent transport theory and rough surface modeling of 

snow. ice and vegetation. 

-Gerstl- Incoherent transport theory \'IHh empirically detennined 

phase functions. 

-Other researchers- optical, infrared or microwave experimental. 

149 

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Jf84 21953 

MEASURING AND MODELING OF THE DIELECTRIC PROPERTIES AND 

ATTENTUATION QF1Vf.GETATION Ii"" n '/. 

F. Ulaby ~ U. of Kansas \I tYlt \~ \\\. ., \ '-) v\<'!(. L 1'." 

INVESTIGATION SYNOPSIS -\JvV4 

Investigation Objectives: 

(1) To measure the microwave dielectric properties of vegetation material as a function of moisture content and microwave frequency, 

(2) to develop dielectric mixing models for the vegetation-water mixture, 

(3) to develop a model for the loss factor of a vegetation canopy, 

(4) to relate the results of (1) and (2) to (3), and 

(5) to test the model in (3) against direct canopy transmission 

measurements. 

(b) First-Year Objectives: 

(1) To build dielectric systems, develop measurement techniques for 

vegetation samples, and calibrate the system using materials of 

known dielectric properties, 

(2) to make a limited number of measurements of the dielectric 

properties of plant samples, 

(3) to demonstrate the feasibility of direct canopy transmission 

measurements, and 

(4) to examine dielectric mixing models. 

158 

_ ..... , •• ,,~ ... ~.. ~tI' • 
(c) Technical Progress and Accomplishments 

(1) All first-year objectives have been realized. 

(2) Approximately 70 percent of the overall investigation objectives have been realized, and we expect to realize all stated objectives by the end of this two-year investigation. 

(d) Results/Scientific Findings 

(1) Microwave dielectric measurements of vegetation material 

• Volume: The amount of data acquired in this project is at least 

an order of magnitude greater in volume than the total cumulative 

amount of data reported in the literature to date. 

• Firsts: This is the first investigation to generate spectral 

measurements of the dielectric constant of vegetation material in 

the micro~Jave region. Also, this is the first study to establish 

the importance of salinity (of the liquid contained in the 

vegetation material) as it relates to dielectric properties at 

frequencies below 4 GHz. 

(2) Model for the Dielectric Constant of Vegetation Material 

Several dielectric mixing models were examined in terms of the 

measured data; some of the models were rejected while others were 

extended. Although the number of potentially applicable models has 

been narro~/ed to two fundamentally different types. it was not 

possible to proceed further until additional experiments are 

conducted. 

(3) Measurements of Canopy Loss Factor 

Previous attempts (by Kansas University investigators as well as by investigators ~t other institutions) to measure the loss factor 

(inverse of transmissivity) of vegetation canopies at microwave 

frequencies have led to poor estimates, at best. A new technique 

was developed in this investigation which has proven to be both 

accurate and repeatable. The technique was used to measure the 

loss factor of soybeans and corn canopies over the full growing 

season and of wheat heads and stalks separately. 

(e) Significance to General Research Area (e.g., Atmospheric Studies, 

Microwave, etc.) and (f) Relationship to Other Fundamental Research 

SRAEC Investigations 

The results outlined above should prove very useful in the 

development of future models of the radar backscattering coefficient of vegetation canopies. 

(9) Second-Year Objectives 

/ 

See (a). (This is a two-year project). 

159 

~ ... _ ...... - •. ~.~.*'" .............. , ............ . 

\ 

\ 

\ 
.' 

(h) Study Participants and Affiliations 

F. Ulaby, Principal Investigator 

C. Martin, Co-Investigator, Asst. Prof. of Botany 

R. Jedlicka, Graduate Student pursuing a Ph.D. degree. 

C. Allen, Graduate Student pursuing a Ph.D. degree 

M. El-Rayes, Graduate Student pursuing a Ph.D. degree 

M. McKinley, Graduate Student pursuing an M.S. degree 

(i) Publications 

(1) Ulaby, F. T., and R. P. Jedlicka, "Microwave Dielectric Properties of 

Plant Materials," accepted for publication in IEEE Transactions of 

Geoscience and Remote Sensing, 1984. (Attached) 

(2) Jedlicka, R. P., and F. T. Ulaby. "Measurements of the Microwave 

Dielectric and Attenuation Properties of Plants," National Radio Science 

Meeting (URSI Commission F). University of Colorado, 

Boulder, January 5-7, 1983. (Abstract attached) 

(3) Ulaby. F. T., R. P. Jedlicka, and C. T. Allen, "Measuring and Modeling the Dielectric ·:md Attenuation Properties of Vegetation," to be 

presented at the International Union of Radio Science Meeting (URSI 

Commission F), Toulouse, France, January 16-20, 1984. (Abstract 

attached) 

(4) Allen, C. T., and F. T. Ulaby, "Modeling the Polarization Dependence of 

the Attenuation in Vegetation Canopies," to be presented at the 1984 

International Geoscience and Remote Sensing Symposium (IGARSS '84), 

Strasbourg, France, August 27-30, 1984. (Abstract attached) 

(5) Ulaby, F. T., "Microwave Properties of Vegetation Canopies: An 

Overview," International Colloquium on Spectral Signatures of Objects in 

Remote Sensing, Bordeaux, France, September 13-16, 1983. (Attached) 

.1.60 

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.. 

R.K Moore, H. 

oW 

THE SOURCES OF RADAR SCATTE~ING t\~,,\,~. V 

ZOllghi' L.K Wu, A. Mifi, F.T Ulaby 

U. of Kansas 

ORIGINAL PAGE IS 

OF POOR QUALITY 

OBJECTIVE: Determination of the backscatter sources in vegetation canopies 

and surface targets. 

OBSERVATION: Suppose a Radar Scatterometer is used to measure the backscattering 

coefficient crO of a canopy. 

FUNDAMENTAL QUESTIONS: 

I) How much of the backscattered energy is due to: 

a) Direct volume backscatter by the can~py? 

b) Di rect backscat ter by the soi I (inc Iud ing at tenuat ion 

effect of the canopy) ? /<r""'{~1'«f.'" 

c) Indi rect backscatter by soi I/vegetat ion ~-t.f"..jtwt-ffifl? 

2) What are the relative roles, in terms of scattering? 

a) The leaves ? 

b) The stalks ? 

c) The fruits ? 

d) The surface (i n surface targets) ? 

e) The volume ( within the surface) ? 

APPROACHES: To understand the wave target interaction process, experiments 

need to be coducted and models developed in areas of: 

I) Dielectric Properties 

2) Attenuation Properties 

3) Volume Geometry 

4) Backscattering Properties 

5) Emission Properties 

MEASUREMENT TECHNIQUES: 

I) Conventional Backscattering Measurements 

2) Backscattering Measurements of Constituents * 

3) Range Probing Measurements 

4) Canopy Attenuation Measurements 

5) Active/Passive Measurements 

BACKSCATTERING MEASUREMENTS OF CONSTITUENTS IN VEGETATION CANOPY: 

I) Stalk Contribution to v 0"" 

2) Leaves " I, II 161 

3) Fruits " II II 

- .. -- .". , ~ .• ' __ .......... ~_ .. •• ... · •• _. ___ ~ ........ _ ... , .. t ........ ~. ~ •. _. ; • .,. ........ ~.., ~oI'. • . ............ , ...... __ ...... . 
TOOLS NECESSARY FOR PRECISE MEASUREMENTS: 

OR1GINAl PACT: [3 

OF PO~)~{ QUALlTV 

A volume probe which enables measurements of scattered energy 

from small portions of the target, such as leaves, stalks, etc. 

SYSTEM DESCRIPTION (Volume Probe): 

A fine-resolution short-range FM-CW radar scatterometer was used 

~/ith the following specifications: 

Operating Frequency: 

Modulation: 

FM Rate (PRF"): 

RF Bandwidth: 

IF Bandwidth: 

Range Resolution: 

Antenna System: 

Polari zat ion: 

One-Way 3-dB Beamwidth: 

Focusing Range: 

Depth of Focus: 

Antenna Gain: 

Transmi tt Power: 

MEASUREMENT PROCEDURES: 

spectrum 

scatterometer ~ analyzer L,----, 

R = cF.fl 4F B I m 

TARGETS OBSERVED: 

l-

(11 

5 

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150 Hz 

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300 Hz 

6.67 cm 

Focused Horn Fed Parabolic Dish 

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2.5'in the Azimuth Plane 

2.9°in the Elevation Plane 

3.5 meters 

2.5 to 6.0 meters 

36 dB @ 10.0 GHz 

13 dBm @ 10.0 GHz 

'--------

IF Frequency 

1) Crops: Corn, Milo, Wheat, Soybean 

2) Surfaces: Concrete Walkways, Grass, Asphalt Pavements, Soil 

162 
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OF. POOR QUALITY 

RF module 

Figure I. The antenna structure & various system components. 

163 

K.· .~~ >" •••.••• _ .... ,.~ •.•• '"-''' ~ -
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/ 

RESULTS: 

.. / 

\. RESULTS: 

The results for the crops were obtained using defoliation experiments. 

1) Immature corn (vert ical): 

a) The cluster of leaves on top of the plant is the main 

backscatte~ing source. 

b) ~talk has insignificant contribution to the backscatter. 

c) 22 dB loss due to the entire plant. 

2) Mature corn (vertical): 

a) The cluster of leaves on top of the plant is the main 

backscattering source. 

b) The leaves around the cobs are the next main source. 

c) The tassel, cobs and stalk have insignificant contribution 

to the bacKscatter. 

d) 6 dB loss due to the entire plant. 

3) Mature corn (30° incidence angle): 

a) In the absence of leaves, backscattering is strongest at 

the lowest portion of the stalk and weakest at the top of 

the stalk. 

b) In the presence of leaves and stalks, backscatter from the 

leaves strongly dominates the total return. 

c) The cluster of leaves on top of the plant is the main 

backscattcring source. 

4) By comparison, it may be suggested that the top cluster of 

the leaves exhibit an isotropic hackscattering pattern. 

5) In all cases, most of the loss introduced by the plant. 

is due to the top leaves. 

6) Backscattering from a corn leaf is about 15 dB higher at 

near-normal ~han near-grazing. 

Mi 10 plant. 

1) Mature milo (vertical): 

a) The main backscattering source is the head of the Milo. 

b) The next major source is the combination of the leaves in 

the lower part of the plant. 

164 
Milo results cont. 

RESULTS: 

c) Contribution of the stalk to the backscatter is insignificant. 

d) II dB loss due to the entire plant (8 dB due to the head 

and 3 dB due to the leaves). 

2) Mature milo (300 incidence angle): 

a) The main backscattering source is the head of the milo. 

b) The backscattering from the head may be isotropic. 

c) The leaves laid in the plane of incidence showed weaker 

returns than the ones laid in the plan~ transv~rse to the 

plane of incidence. Furthur defoliation experiments are 

needed. 

Whea t p I an t • 

I) At vertical incidence, the top of the plant (where the head 

is located) and the cluster of the wheat stems near ground 

have stronger returns than the leaves and the middle stems. 

2) At 3if incidence angle, the same results (as the above) 

were obtained. 6 dB loss was introduced as the transmitted 

energy passed through the plants. This loss was mostly due 

to the wheat heads. 

RESULTS: Soybean plant. 

I} The backscatter from nearly vertical measurements decreasesd 

as the penetration depth into the plant increased. 

2} 17 dB loss due to the whole plant, and 14 dB of it was due 

to the lower half portion of the plant where the stems are. 

3) At 300 incidence angle, the strongest backscatter was from 

the top leafy part of the plant. 

( 

165 
RSULTS Surface targets. 

1) Concrete: Top surface. Bottom surface. 

2) Grass: Blades. Soil surface. 

3) Rough ~oil: Top surface, Multiple scatter from clods, Volume 

scatter from clods, possibly soil volume scatter. 

4) Asphalt #1: Top surface, Volume scatter from within the 

asphalt pavement 

5) Asphalt #2: Top surface, Volume scatter from within the 

asphalt pavement, Bottom of the asphalt layer. 

The incidence angle for the above targets: ~ ~ 20~ 20~ 2~ respectively 

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EFFECTS OF VEGETATION CANOPY STRUCTUR~ ON MICROWAVE SCATTERING 

J. Paris 

NASA/JPL 

ANNUAL REPORT 

EFFECTS OF VEGETATZON CANOPY STRUCTURE 

ON MXCROWAVE SCATTERXNG 

a ~ACK F. PARxa (~ET PROPULB%ON LAB.' 

e BROAD GOALa XNCREASE UNDERSTANDXNB 

OF ROLE OF CANOPY STRUCTURE ON RADAR 

BACKSCATTERXNG BV VESETATXON ~ SOZL 

fiB 

a 

FXRSTVEAR= DEVELOP MODELS THAT USE 

STRUCTURE EXPLXCXTLV AND PREPARE FOR 

EMPXRXCAL FXELD EXPERXMENTS 

TECHNXCAL PROSRESSe 

1. SXNGLE-SCATTERXNG MODEL WAS 

DEVELOPED WXTH POLARXZATXDN~ 

ELEMENT eXZE. AND ELEMENT 

ORXENTATXON AS PARAMETERS 

2. MODEL SENSXTXVXTV BTUDXES WERE 

COMPLETED 

3. MODELS WERE TESTED AaAXNST KU/ 

KSU CORN AND WHEAT DATA 

4. PREPARATXON FOR FVB4 FZELD 

STUDXES WAS STARTED 

i··~ • 

( 

.. ~: 

~ 'ti 
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"'-.! 

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ANNUAL REPORT (J.F. PARXS) PAGE :2 

a BCZENT~FXC FXNDXNGB 

1. MODEL FORM FOR CROSS POLARZZATXON DiFFERS FROM THAT OF LXKE 

POLARXZATJ:ON 

2. USE OF RATXOB OF BACKSCATTERXNG 

COEFFXCXENTS CAN ZeOL-ATE CANOPY 

ELEMENTS ORXENTATZON FEATURES 

::Sa 

4. 

5. 

**6. 

'THXN# CANOPY BACKSCATTER XB 

MOST AFFECTED BV EXTXNCTXON 

CROBB SECTXDN AND NUMBER OF 

ELEMENTS PER UN%T AREA 

'THZCK' CANOPY BACKSCATTER XS 

MOST AFFECTED BV RATXO OF BACK 

SCATTERXN8 AND EXTXNCTXON 

CROSS SECTZONS 

CANOPY-SURFACE XNTERACTXON CAN 

ADD SZGNZFXCANT BACKSCATTER 

00 

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PREDXCTXONB TO OB~~RVATXONB 

(R2 XNCREASED rROM .79 TO .9::S> 
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CORN FI ELD 1 3, 1980, 17 VV 

SIGMAO = SIGMAOFC * (1 - T3) + SiGMAO. * T3 

WHERE 

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LF "" 1 / [2 * QL * SEC(SO)] 

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Q~ = 1.3 * MWL 

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SIGMAO. B SURFACE SIGMAO 

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GLAL = LEAF GREEN-LEAF AREA <1'12) 

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..... 

0) 

.t:> 

~ 

\ 

\\ 

ANNUAL REPORT (J.F. PARXS) 

U SZGNXFXCANCE OF FiNDXNSa 

PAGE :3 

1. NEW MODEL CAN BE USED TO 

XSOLATE CANOPY ELEMENT aXZE. 

ORXENTATEON. AND WATER CONTENT 

FROM RADAR BACKSCATTERXNG 

2. NEW MODEL CAN AXD XN THE DESZGN 

OF FUTURE FXELD EXPERXMENTS 

~ RELATXONSHXP TO OTHER SRAEC STUDXEB 

m 

1 • KU TRANSMZTTANCE MEASUREMENTS 

2. KU SOURCES-OF-SCATTERXNB STUDY 

3. awu DXaCRETE-ELEMENT SCATTERXNG 

STUDY 

SECOND (CURRENT) VEAR SOALS 

1. XMPROVE MODEL TO iNCLUDE 

MULTXPLE SCATTERXN9 AND TO 

RESPONDE TO BXOPHVaXCAL 

PARAMETERS 

2. TEST MODEL AeAXNST JPL RADAR 

SPECTROMETER DATA 

_ -J ""t1 :.:J 

>~ ~. :.; .'-

r~; -'I 

(.- . :~ .. ,., 

. 

.-"':. ,,-". 
" , , ~ 

.. AI">'" ,1'\ OR1GtNAt. P '\:&1:' ~-" 

OF POOR QUALiTV 

185 

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, 

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f 

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! ' 

; 

I. 

1<' R. 

:; 

W. 

" . 

S. 

D. 

Fraser - Pearce 

Gerstl 

Diner 

III.C.3~ ~ATMOSPHERIC EFFECTS STUDIES 

Atmospheric Effect on R~mote Sensing of the Earth's Surface 

The Characterization of Surface Reflectance Variation Effects 

of Remote Sensing 

Multidimensional Modeling of Atmospheric Effects and Surface 

Heterogeneities on Remote Sensing 

Bidirectional Spectral Reflectance of Earth Resourcse: Influence 

of Scene Complexity and Atmospheric Effects on Remote Sensing 

186 
'~' 

.; 

'_ .• -r ~"Jo..\.~ ~~ -~$.' 

, " - .. ' ":"'" -.. .,. -:--" ---":' ~: ~.. . _'5 ~ ~- " i~ ·)#1 7'; 

..... 

co 

" 

BROAD GOALS 

ATMOSPHERIC EFFECTS ON REMOTE SENSING OF THE EARTH'S SURFACE 

R. Fraser and Y. Kaufman 

NASA/GSFC 

ATMOSPHERIC EFFECT ON REI-lOTE SENSING OF THE EARTH'S SURFACE 

o THEORETICAL INVESTIGATION OF THE MAIN CAUSES OF ATMORPHERIC EFFECTS. 

o MEASUREMENT OF THE ATMOSPHERIC RADIATION PROPERTIES AND THEIR CORRELATION WITH AEROSOL 

PHYSICAL CHARACTERISTICS. 

o DEVELOPMENT OF ATMOSPHERIC MODELS THAT WILL ACCOUNT FOR THE MAIN ATMOSPHERIC EFFECTS. 

o DEVELOPMENT OF ATMOSPHERIC CORRECTION ALGORITHr~S. 

FIRST TWO YEARS OBJECTIVES 

00 

-n::a 

-o?} 02 

0'", Alf-

,o~ 

C:? :.'t" (;1 

!:; lti 

~~ 

o THEORETICAL STUDY OF THE RELATIVE IMPORTANCE OF THE AEROSOL SCATTERING, ABSORPTION, AND SIZE 

DISTRIBUTION IN REMOTE SENSING. 

o LABORATORY SIMULATION OF THE ATMOSPHERIC EFFECT AND COMPARISON WITH 3-D MODELS. 

o STUDY OF THE ATMOSPHERIC EFFECT ON THE SEPARABILITY BETWEEN FIELD CLASSES. 

o FIELD MEASUREMENT OF THE CORRELATION BETWEEN THE ATMOSPHERIC EFFECT AND THE ATMOSPHERIC 

AEROSOL CHARACTERISTICS • 
! 

~~1!"_ ~~.; ;: ~.:-.~.~-"'~ 

, i 

, ~~ 

, 

I-' 

co 

co 

TECHNICAL PROGRESS AND ACCOMPLISHMENTS 

o THE FIRST THREE OBJECTIVES HERE ACCOMPLISHED AND SU!11HARIZED (SEE PUBLICATIOns). 

o FIELD i'1EASUREI'1ENTS WERE DESIGNED AND THE FIRST NEASUREMENTS TAKEN. 

SCIENTIFIC FINDINGS AND SIGNIFICANCE TO THE GENERAL RESEARCH 

00 

~" ?: 

"\1 r-;:, b ~" 

~2 :~!. r , __ ...~ . ., " , . L._ '" 

";':"~ 't"-} 

r:. 

f~!.. .. -:~! 

o AEROSOL ABSORPTION HAS A SIGNIFICANT EFFECT ON REr·WTE SENSING NAINLY FOR HIGH SURFACE 

REFLECTANCES (R= 0.3). AEROSOL ABSORPTION IS NOT KNOWN ACCURATELY; BUT FOR MODERATE VALUES, 

IT HAS TO BE ACCOUNTED FOR IN MODELLING AND CORRECTION ALGORITHr~S. 

o REMOTE SENSING OF CONTRAST, SUCH AS THE VEGETATION INDEX, IS ONLY WEAKLY AFFECTED BY AEROSOL 

ABSORPTION BUT IS AFFECTED BY AEROSOL SCATTERING. 

o THE ATMOSPHERIC ADJACENCY EFFECT (EFFECT OF A BRIGHT FIELD ON THE APPARENT REFLECTIVITY OF A 

NEARBY DARK FIELD) HAVE BEEN VERIFIED EXPERH1ENTALLY IN THE LABORATORY AnD FIELD. THESE 

l\IEASURm~ENTS ARE USED TO TEST THEORETICAL NODELS. 

o THE ADJACENCY EFFECT WAS SHOWN TO REDUCE THE SEPARABILITY BETWEEN FIELD CLASSES (IN 

ADDITION TO ITS EFFECT ON SPATIAL RESOLUTION AND CLASSIFICATION ACCURACY). 
":'t&~~1i 

~ \ 

~~ 

\. 

..... 

Ct"' 

-0 

./ ,-- ~~ 1'~ ~)"-:'" ,. -.1"": ., -~-~ ;-., -:-:-.-,-... . ~~~ •. • _-::-:- ';, --·,,::_c.::::·~~,,,:._..........-io-~ 

RELATIONSHIP TO OTHER FUNDAMENTAL RESEARCH SRAEC INVESTIGATIONS 

o THIS INVESTIGATION IS RELATED TO THE ATMOSPHERIC STUDIES THAT AIM TO DEVELOP MODELS OF 

ATMOSPHERIC RADIATIVE TRANSFER AND TO PARAMETERIZE THE ATMOSPHERIC EFFECTS. 

NEXT YEAR OBJECTIVES 

o 

o 

DEVELOP PROCEDURES TO J.1EASURE THE AEROSOL SCATTERING AND THE AEROSOL ABSORPTION FROM 

SATELLITE DATA AND TEST THEM AGAINST VALUES DERIVED FROM SURFACE OBSERVATIONS. 

DEVELOP AN ATMOSPHERIC CORRECTION ALGORITHf·1 THAT IS BASED ON THE \I1EASURED PARAMETERS • 

APPLY THE CORRECTION TO SATELLITE OR AIRCRAFT DATA AND COMPARE WITH IN SITU MEASUREI4.ENTS. 

o ANALYZE THE FIELD MEASUREr'lENTS OF THE CORRELATION BETWEEN THE ATMOSPHERIC EFFECT AND THE 

ATMOSPHERIC AEROSOL CHARACTERISTICS. 

00 

:n::o 

-oQ 

02 

~~ 

0-0 

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~ 

: 

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...... 

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o 

STUDY PARTICIPANTS 

PRINCIPAL INVESTIGATOR: 

CO-INVESTIGATOR: 

DR. ROBERT S. FRASER 

NASA/GODDARD SPACE FLIGHT CENTER 

GREENBELT, 'f'.1ARYLAND 20771 

DR. YORAI~ J. KAUFMAN 

UNIVERSITY OF MARYLAND AND 

NASA/GODDARD SPACE FLIGHT CENTER 

GREENBELT, r~ARYLAND 20771 

PUBLICATIONS (SEAEC SUPPORTED RESEARCH) 

00 

."", 

"t1Q Oz 0.,,,,: 

::Jr:. 

tC?=" c_ .,.~ 

.h £~) c: ~~1 

;::£; 

1) YU. !IJ.EKLER, Y. J. KAUFMAN, AND R. S. FRASER, 1983, REFLECTIVITY OF THE 

ATTIJ.OSPHERE-INHQr'lOGENEOUS SYSTEr~. LABORATORY Sn~ULATION, IN PREPARATION, TO BE SUBMITTED TO 

J. ATMOS. SCI. 

2) R. S. FRASER AND Y. J. KAUFMAN, 1983, THE RELATIVE IMPORTANCE OF AEROSOL SCATTERING AND 

ABSORPTION IN REHOTE SENSING, "-:L CONF. ON ATMOS. RAD., BALTHWRE, MD. 

3) Y. J. KAUFMAN AND R. S. FRASER, 1983, DIFFERENT ATMOSPHERIC EFFECTS IN REMOTE SENSING OF 

UNIFORN AND NONUNIFORN SURFACES, ADV. SPACE RES., £, 147-155 • 
~." ~ ,.. •.• .,. _ .. __ ._;": ".r- ... - .... "'..,... ... --------""-----

2ZiCiJGl!iiC OOi?li£illl "Ir'"",.,"~ .... ,~,-, --, -.. 1"",·1,"-""\ ... · rit"':-" r;;, . .' 

~ 

\ 

'~~ 

, 

\ 

I 

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, 

..-

\0 

l-' 

PUBLICATIONS (SRAEC PARTIALLY SUPPORTED RESEARCH) 

4) Y.J. KAUFMAN AND R. S. FRASER, 1983, THE ATMOSPHERIC EFFECT ON CLASSIFICATION OF FINITE 

FIELDS, ACCEPTED FOR PUBLICATION IN REM. SENS. OF ENVIR. 

5) Y. J. KAUFMAN, T. W. BRAKKE, AND E. ELORANTA, 1983, FIELD EXPERIMENT TO MEASURE THE 

RADIATIVE CHARACTERISTICS OF A HAZY ATMOSPHERE, Y. CONF. ON ATt1. RAD., BALTIfvlORE, ND. 

6) Y. J. KAUFMAN AND R. S. FRASER, 1983. A~MOSPHERIC BFFECT ON SEPARABILITY OF FIELD CLASSES, 

IN PREPARATION TO BE SUBNITTED TO INT. J. OF REi'l. SENSe 

7) Y. J. KAUFMAN, 1983, ATMOSPHERIC EFFECT ON SPATIAL RESOLUTION OF SURFACE IMAGERY, SUBMITTED 

FOR PUBLICATION TO APPLIED OPTICS. 

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IJi 

DISH OF 

HYDROSOL 

LAMBERTIAN 

REFLECTING 

SURFACE 

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" 

ORIGINAL PIl.G[ is 

OF POOR QUALITY 

CHARACTERIZATION OF SURFACE REFLECTANCE VARIGATION EFFECTS ON RENOTE SENSING 

o GOALS AND OBJECTIVES 

w. Pearce 

EG&G 

o To model and characterize the effects of scatte~ing 

phenomena impacting remote sensing in the visible: 

Aerosol profile variations 

Aerosol size distribution variations 

• Viewing angle variation 

Bidirectional reflectance function variation 

Horizontal aerosol inhomogeneity <clouds) 

o Atmospheric effects algorithms 

Deve I 1:1 prt1ey,t 

Sensitivity studies 

o FIRST YEAR OBJECTIVES 

o Tool building 

Revision of simulation 

operational environment 

Val idat ioY, 

codes tCI suit 

( CTRANS, ARTRAN, 

Micro-to-mainframe communications 

InteractIve graphics 

FFT (CIY, r" i Ct'C') 

Linear filterIng 

new 

MieJ 

Cubic s~line interpolation, differentiation and 

i Ylt egt'at i OY, 

o Aerosol vertlcal profile variation effects 

Test nOlse sUDpression techinques 

BC".Il",dat'y effect 

MTF 

Line spread function 

• From boundary Intensities 

• From inverse Fourier transform of MTF 

o Vlewing angle effects 

Baseline Lambertian ground refloctance 
/ 

o TECHNICAL PROGRESS AND ACCOMPLISHMENTS 

o Software tools developed 

ORIGINAL PAGE is 

OF POOR QUALITY 

CTRANS Monte Carlo code restructured to iMprove 

efficieY'lcy 

ARTRAN created from CTRANS by removal of finite 

clouds capability 

RRTRAN validated by cOMparison with previous 

resl.ll ts 

Mil? code revised to suit 

ComMunlcations software Modifled to perMlt 

exchange of files between mainframe and micro -

c.:.mputet's 

Software packages developed for 

to permit interactive analysis 

,"eStl J. t s 

fI1 ict'.:.cc.mpllt et' 

c.f sifl1l.l1at ion 

* GraphiCS 

-II' FFT 

* Linear filtering 

• CubIC spline interpolation, 

differentiation, and lntegratlon 

o Aerosol vertical proflle studies 

Moderate aerosol optical 

shiftIng tropospherIC 

st t'at .:.sphet'e. 

depth simulatlons 

aet'c'sols 1 nt 0:. 

* MTF * Boundary effect 

* Llne 5Drea~ function 

o Viewing angle effects 

the 

SimulatIons with Lambertian ~round reflectance 

Moderate aerosol optical thickness 

Bound':H'y effect 

20;:' 
co 

r 

I 

\ 

I 

r. 

r 

f 

~ ,;,~ 

o RESULTS, FINDINGS 

o Moderate aerosol optlcal deeth profile variations yield 

approximately linearly scaled variations in the line 

spread function compatIble wlth single scattering model 

exoectat io:o\",s. 

o Off-nadir vIewing angle simulations qualitative only. 

Required: co:~parisons with nadIr view cases with 

modIfIed vertical optIcal depth. 

o RELATIONSHIP WITH OTHER SRAEC INVESTIGATIONS 

o 

o Complements radlatlve transfer models of Diner and of 

Gerstl 

o Can treat finite clouds and polarization effects 

o Can implement and test impact of reflectance models 

from Vanderbilt, Smith, Norman, and Strahler 

SECOND YEAR OBJECTIVES 

Aerosol size distribution effects on the 

atmospherIC s~read function 

Bidlrectional reflectance effects 

* homogeneous reflectance, 

t'eflectlvlty 

* Inhomogeneous reflectance types 

* 

* 

PolariZatIon sensitivity 

EXIMine effects of clouds withIn and near fj.(~~d cof VIew 

203 
Parameterization 

()R:G;;·~r,L i~~.~'_f(;~ ;:~1 

)F POOR ~Jj;.!..IT'f. 

* Characterize inner and outer parts of the 

spre.:?d function 

* Examine coupling with bidirectional ground 

refl.ect.:?nce 

a STUDY PARTICIPANTS 

o William A. Pearce 

o Y. Kaufman -- consulting 

a PUB~rCATIO~S 

o Pl.:?nned: lQ 84 

Code descrlption, spread function variation 

with optlcal depth, aerosol profile, viewin~ 

angle, and aerosol size distribution 
• 

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~EROSOL DENSITV 

~\ ", "'-, 

ORlGIN/iL F;~t:~: :~"! 

OF POOR QUALITY 

.. , 

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'''" ,."'., 

" ',-" 

0. 0001t L---L-...IL..-.....l.-....L--l.-_L_L-L-J._'--...o...-. _____ "-'-" ....... ____ -.....I , 

0. 20. 40. 60. 

HEIGHT ( km ) 

ART001.CAP 
"",, 

Or.i·::~i I,' ' • ' • i 

INTENSITV CROSSING ALBEDO BOUNDARV OF f'l.)Ji;' C~'i:'~'i'''''f ~----.---------------.--~-----------------------~ 

-

0.080 

0-4 

~~ .... 

LAJ 

~~ 0.040 .... 

DISTANCE FROM BOUNDARY (km) 

ART001.CAP solar zenith ang12 ~ 40 deg. 

20li 
M 

»: 

»: 

c 

(.1 

AEROSOL DENSITV 

omG1~r""i.. r J\CC :~ 

OF POOR QUALITY 

207 
INTENSITV CROSSING AL9EOO BOUNDARV 

~ 0.05 .... 

VI 

iii 

~ 0.04 .... 

0.02 

.,.,,--

----------------~~- 0.000~-------------

DISTANCE FRO~ BOUNDARY 

ART002.CAP 

208 
,. 

AEROSOL DENSITY --~----------~~~ 

99099J 1\ 

M 

* * a::: 

u 1.0\Z10\Z1~ 

~. 

0.' 

c. 0. 1000~ 

I..d 

~ 00010J~ c~ 

0.001 

V 

ART003.CAP 

209 

OI~IG!Nf:.t. Pt\GE is 

OF POOR QUALI"N 

.~ 
.... 

VI 

ffi 

INTENSITY CROSSING ALBEDO BOUNDARY 

OR!GfNr.,~: rr;:: ~::, 

OF. P00rl QUAUTft 

~ 0.040 .... --------.-- . 

0. 020r 

~ ---------

0.000t -~.0 ;;;,-:1 \-1 

-~.0 

I-~:-:;.=-='--±;F:, -~ 0.~ ~~~~FI=l DISTANCE FROM BOUNDARY Km) 

ART003.CAP 

210 
, , 

.. 

" 

" 

--~ '~. 

-- (~ 

~1JLTIDJMENSIONAL f"bDELING OF AOOSPHERIC 

EFFECTS AKJ SURFACE HETEROGENEITIES ON REMoTE SENSING 

S. Gerstl 

Los Alamos Natl. Lab. 

BROAD GOALS PND OBJECfIVES: 

IMPROVE UNDERSTANDING AND QUANTIFY EFFECTS OF 

A) ATMOSPHERE AND ITS VARIABILITIES 

• TURBIDITY/AEROSOLS 

• CLOUDS/HAzE 

B) SuRFACE HETEROGENEITIES 

• STRUCTURAL (CANOPy ARCHITECTURE) 

• hiGUlAR CBRDF BOUNDARY CCtJD.) 

o SPATIAL (ADJACENCY EFFECTS) 

STUDY PARTICIPMITS: S. GERSTL (PI) 

(ALL AT Los ~s A. lARDECKi (PH.D. CoUABORATOR) 

NATIONAL lABoRATffiY) C. SIJVMER (POSTDOC STAATING JAN. ~m 

211 
'1 

" 

I 

1 

! 

t 

t 

I 

I 

I 

, I 

FIRST yt:"...AR OI3JECflVES 

• ADAPT EXISTING RT CODES TO REMOTE SENSING APPLICATIONS 

• IMPLEMENT BROAD ATMOSPHERIC DATA BASE 

.. VALIDATE conr:s AND DATA 

• DEFINE AND VERIFY A COUPLED ATMOSPHERElCAf\.'OPY MODEL 

• OuANTIFY EFFECTS OF CANOPY (BIOPHYSICAL) PARAMETERS 

., ADD GENERAL BRDF SURFACE BOUNDARY CONDITIONS 

SEaJrJD YEAR OBJECTIVES 

• ESTABLISH MJLTI-LAYER MODELS FOR PARAr'1ETRIC STUDIES 

$ PERFORM SENSITIVITY STUDIES 

., QuANTIFY EFFECTS OF ATII()SPHERIC TUP3IDITY AND SURFACE BRDF 

• EVALUATE EFFECTS OF SEMI-TRANSPARENT CLOUDS AND HAZE 

PUBLI CATIONS 

• 2 PAPERS OF FIRST 1~ YR. RESULTS ARE IN PREPf~TION 

212 
r: 

:. 

,:. 

-.-

TEa~N I CAL PROGRESS AND ACCOM'LI SHr'ENTS 

~ AcHIEVED ALL FIRST-YEAR OBJECTIVES 

~ DEMONSTRATED APPLICABILITY OF DISCRETE-oRDINATES FINITE-ELEMENT 

CODES TO ANALYZE EFFECTS OF 

.. A1NOSPHERIC RAYLEIGH AND MIE SCATIERING 

.. ANISOTROPIC LEAF SCATIERING 

• NON-lAMBERTIAN AND SPECULAR GROUND REFLECTANCE 

CD VERIFIED At{) VALIDATED COUPLED ATI1OSPHEREICANOPY MODEL AGAINST 

FIELD MEASUREMENTS 

e ExPANDED CAPABILITIES OF RT-cODES TO TREAT GENERAL BRDF BOUNDARY 

CONDITIONS 

• CoNCEPT OF KAUTH-THOMAS GREENNESS TRANSFORM CONFIRMED WITH OUR 

COUPLED ATMO./CANOPY MODEL 

., NEW PHYSICAL INTERPRETATION SUGGESTED FOR KAUTH-T~a-1AS BRIGHTNESS 

TRANSFORM AS A MEASURE FOR ~TM. OR Vo OVER VEGETATIVE SURFACES 

213 

. , ............ " .-.---....... -'~ ...... -..... ".. .. ~. ~ ....... ,' 
.. 

1; 

j. 

~ 

t',-

! 

i 

r 

t 1) 

" ~ 

,. 

t 

f· 

t 

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I 

2) 

RESULTS/SCIHITIFIC FINDINGS 

ORIGINAL PAGE (8 

OF POOR QUALITY 

AWtOSPHERIC EFFECTS (AEROSOLS AND MOLECULAR SCAITERING) PLAY 

MAJOR ROLE IN VISIBLE} MINOR IN NEAR-IR: 

FOR Vo == 50 TO 5 1<Jv1: 

100 TO 200% IN VIS. WiSS A + B) 

5 TO 10% IN tHR Cf'ES C + D) 

f1SS - GREENNESS IS CONSTANT (± 1%) 

f'1SS - BRIGHTNESS B ~ C. 2"'ATl'1. (MEASURE FOR Am.) 

I NCLUS I ON OF AN I SOTROP I C LEAF SCA ITER I t\1(j (~AND r) 

IMPROVES AGREEt-1ENT WI111 FIELD t1EASUREMENTS: 

FOR G == 0 TO -0.5: 

AlVIS. -- REFL:-

5% ABOVE ATMOSPHERE 

AI~~L~ 5% ProVE CANOPY AND ATM. 

214 
ORIGINAL PAGE IS 

OF POOR QUALITY 

RESULTS/SCIENTIFIC FINDHIGS 

(CONTINUED) 

3) NON-lAMBERTIAN AND SPECULAR SURFACE REFLECTANCE <BRDF) AFFECTS 

twllR SA TEll.. ITE t1EASUREMENTS ONLY I NS I GN I F I CANTL Y: 

• WITH CANOPY: ~IREFL,« 5% ABOVE ATM, 

(LAI = 1.5) 5% IN VISSIBLE ., WITHOUT CANOPY: ~ I

REFL ,== 

(V 0 = 2:;;KM) 5-15h IN rHR 

4) [OR OFF-NADIR VIEW DIRECTIONS NON-lAMBERTIAN BRDF OF SURFACE AND 

SPECULAR REFLECTION CCY.PotlEtIT t'IA.f..'E SISNIFV'ANT DIFFE!1E1'lCE! 

215 

-a.' ,t·t 0' ~ .... '.,'r"'.,·"lIu, 
I 

I 

I 

I 

I 

! 

I 

! 

l'~I't$; -- . 

SIGNIFlrPNCE OF RESULTS 

A) TO SCENE IDF.NTIFlCATlON FROV1 lANDSAT r'SS DATA: 

• ATt1)SPHERIC EFFECTS 00I'1INATE SIGNAL IN VISIBLE CHANNELS 

(fvSS A + BL BlJr 

• r'Ss GREENNESS IS UNAFFECTED BY ATMOSPHERIC TURBIDITY. 

• NADIR LArIDSAT MEASUREMENTS ARE INSENSITIVE TO SURFACE BRDF. 

B) TO FUTURE AWtOSPHERIC CORRECTION ALGORITI-f·1S: 

• MSS BRIGHTNESS Ml\Y BE USED TO ESTIMATE ATM. TURBIDITY (~TMI OR VO) 

OVER VEGETATIVE SURFACES 

C) TO CANOPY REFLECTANCE MODELING: 

9 ANISOTROPIC LEAF SCATIERING IS SIGNIFICANT TO EXPLAIN GROUND 

TRUTH CANOPY REFLECTANCE MEASUREMENTS, 

@ BlJT NEGLIGIBLE EFFECT ON SATELLITE MEASUREMENTS. 

216 
·~ , 

• 

Id 

0.5 

o =TOP OF CANOPY 

)C =TOP OF ATMOSPHERE 

8a= 29.3 DEGREES 

B.,= 13.7 DEGi~EES 

fJ.,-qJ:s= 25.0 DEGREES 

0.6 0.7 OB OJJ 

Vlavelength (l.trn) 

217 

1..0 
ORIG.!NAl PACE is' 

OF, POOH QUALITY 

LAI= 

$,() 

I r' ~; ,,~ 

tJ.1C 

tJ 

:i 

I 

" 

0.6 O.? O.~ 

flavetength (p, 

21B 

"" - ..... .. ........... . :"', .~ " . ~·~~~~~~~Lt~j.AriO~'~mtl .. !tt!·1I! (&!om,. '9V1'i'W~mu 't illG_At~li#~~V~~Id~~ 
l 

r 

r 

t 

.M~ ~Ttf.E.IJNESS 

k ss JJ 1tt'HrtJ1:t s 

• _s--__ ---} G(LAr:3) 

i _. f 

P.", I).¥ o. 6 

Ai TH. ""r. ..J)E? ry-,) 

21Y 

con.sf. 

G (LAI == I. s) 
C~t:~~."~r: r·'",'··.~ 

tc $":"''<- ':~' .• : :.' Il,'~~ 1 '," 

I1SS al<eENAlcSS (I lV'S. LAI 

HSJ. 2!u~HrNESS b J 

220 
---< • ...,.-

ORIGINAl.. PAGE l~, OF POOR QUALn~ YA~!I S~/L 31t1JF 

ATMOSPHERIC YODEL = 19 216511 "AHfJ.~ 

.lItX-I. f' .. y;, fi: S'" t:I A ~ 

ld 

CANOPy = 0.50 BRDF = G).eo 0.60 0.20 - 1/ () 

0.5 

o =t'OP OF CANOPY 

)( =toP OF ATMOSPHERE 

, = 29.3 DEGREES S:= 13.7 DEGREES r-'1-~s= 25.0 DEGREES 

i(O,B '~.7 0.8 0.9 

Wavelength (IJLm) 

221 

.Sj.S1.0 
lri 

J((Jr~~f $l'l&1FACI! AUF I~~~~~e tm~ SIIt!1~ ~U. 

fC AIJI(JJjI)\jJ 9:" JJ 1(. l.AI1J) • 

. ,CANOPy == ~600 ~~¥ SlIt ~ ttlCO 020 --I /0 

0.5 

D ='roP OIF OO"OPV 

J( =1.':OP OF JAl"MasPHERlZ 

Be= 29.3 DEG.~ETZS 

8.,,= 13.1 DZGRJ?l"ZS 

"'-~IJ= 25.0 C;;;.,~ 

0.6 0.7 0..8 0.9 

lfavelength {jLm) 

222 

os-I·s 

fJ/1 

SPIUutA(. 

IJl 
• ORIGINAL PA0~ ~g 

OF POOR QUAU'N 

VAft'l .r~L JlJl)F 

ATUOSPHERIC MODEL llG 19 216511 ~ II:' ~ tt- 'AHJ).PPJ:.( 

CANOPY = 0.50 BRDF = ®.60 0.60 0.20 ~ /.~/O.l 

- . sjs- 60 

WAVELENGTH = 0.650 p,m 

o = TOP OF ATMOSPHERE 8'1=60 

o = TOP OF CANOPY 8 =60 

Ii = TOP OF ATI.610SPHERE 6'1=30 1 ~ e 

50 ... = TOP OF CANOPY 8'1=30 :J "$ 

G ::::l'o s 

10 

30 60 90 120 150 180 

VievJ' Azimuth Angle 223 

~~ ... -

••• ..a ........ .. ... 

-- ..... 

_.~ 

" 

•••• _ . .. _""" ... .- ....... _~ 

~ ,,~ ...... __ •• _ .... _ ... __ .. __ .. 

._ .. 
~ ..... 

~ '-'" 

u 

e::: 

h 

0 

..;.-) 

() 

~ 

() 

C) 

~ 

c: 

..;.-) 

() 

CJ ,.--I 

e..,..... 

C) 

p::: 

:>. 

0... 

0 

r.::: 

ro 

u 

60 

50 

40 

30 

20 

10 

ORIGINAL PAG:2 [g 

OF POOR QUP.LITV 

ATMOSPHERIC MODEL::: 19 216511 . ~ S~ It,.. 

CANOPY = 0.50 BRDF:= 1.00 0.00 0:20 

r::! 

.,/AVELENGTH = 0.750 J1ffi 

rpv -CPs= 90.0 DEGREES 

o ==TOP OF CA!\OPY 

x ==TOP OF ATMOSPHERE 

-. 

o t-....-__ -J.... __ ,.....:. ___ .!.........-.,_....!...-_-'_~_~ 

o 15 30 45 60 75 90 

View Zenith Angle 224 

~ "":' .... _~ ~~.~ ::..:.. .. :~,:-.:.~..,w...., ....... _ ... ,~, ___ ... _ .... t.III .. ~_""'_ • ..-.:. __ ._.~.,..~'.!w·.\..";,f ....... 
N 

N 

U1 

BIDIRECTIONAL SPECTRAL REFLECTANCE OF EARTH RESOURCES: 

INFLUENCE OF SCENE COMPLEXITY AND ATMOSPHERIC EFFECTS ON REMOTE SENSING 

OVERALL OBJECTIVES 

D. Oi ner 

NASAjJPL 

ItNESTlGATE UTILITY OF ANGULAR VARIATION OF REFLECTION SPECTRA IN IDENTIFICATION/ 

DI SCR Ir·n NAT ION 

STuDY EFFECTS OF CANOPY GEO'''ETRY AND SCATIt::RING 00 RFFtECTANCI: PROPF.~'F I ES OF 

INDIVIDUAL lEAVES 

DETER."'iINE EFFECTS OF ATr'OSPHERIC SCATIERING ON ORBITAL r-EASeREf.'8rrS OF SURFACE 

SPECTRA AND BIDIRECTIONAL REFLECT~~CES 

DEVELOP ATI1JSPHERIC CORRECTION/CQ"'iPENSATION ALGORI~~ 

. "'; 
" 

,.~-. 

I 

t 

I 

! 

i 

!l 

\; 

~ 

i 

! 

I 

! 

! 

!.I 

f 

t: N 

N 

; '. 0\ 

, t 

? ~ 

r. I: 

r , 

• i 

: 1 

.. .... ,_,. ~. __ ~ "-~ ...... ,~: •• ~- ... ~ ~.tp~.'.;o;--.~-. '"';:;,--. .--.--.~....;-. . ..:......:..::: 

SPECIFIC OBJECTIVES 

YEAR 1 

YEAR 2 

SET-UP OF LABORATORY GONIOMETER FOR LEAF BIDIRECTIONAL REFLECTANCE 

ViEASUREMENTS 

DEVELOPfVENT OF ATf'OSPHERIC RADIATIVE TRANSFER ALGORITIiM CAPABLE OF 

HANDLING ~lON-UNIFO;\M A.\jD i~ON-l.Aj-'IBERTIAN SURFACES 

ESTABLISHr"ENT OF LEAF GONIOVETRY CALIBRATION PROCEDURES AND PROCUREfVENT 

OF SM1PLE SPECTRA 

INVESTIGATION OF ATMOSPHERIC SCATTERING EFFECTS ON SURFACE REFLECTION 

US I NG 3-D FOUR I ER TRANSFORt'1 CODE 

ADDITION OF CAPABILITY TO HANDLE HORIZONTAL ATt"OSPHERIC INHor-'OGENEITIES 

IN RADIATIVE TRM~SFER COMPUTATIONS 

D. J. DINER 
ACC~PLISHMENTS AND RESULTS 

3-D FOURIER TRANSFORt1 ATI'1)SPHERIC RADIATIVE TRANSFER CODE DEVELOPED _ 

RESULTS Cor-'PARE FAVORABLY TO t-'Of'lTE CARLO 

WroTH OF AWOSPHERIC POINT-SPREAD FUNCTION DEPENDS ON VIE'.;rr~G AnGLE 

AND ATf1JSPiiERIC SCALE HEIGHT 

DIFFERENT PadER SPECTRA OF DIRECT AND DIFFUSE RADIAnCES IS BASIS FOR 

TECHNIQUE TO DETERMINE AWOSPHERIC OPTICAL DEPTH 

PRELIi'HNARY LEAF GONIOr'IETRY INDICATES SPECTRAL VARIABILITY WITH VIS" 

N~GLE, 

D. J. DINER 
r~~".".,.""..~"'nm-'fl ---

i 

N 

N 

c: 

'~-"""u~.:'-':ilj ... 'T"i ~\\\~'lrr. . . '"1!.11r<:"?-....'~F.~--~-~--................. -4-..... '.-........... ,...........-........., ___ ........,.------:.-~j-'r~·--·r~----.... ,"", ..".,Q'.""\'"'i •.•• =, .•.,..,.,,,-....,..~ . ....,w.::;:_,..,. .•., -- .... ---. 

SIGNIFICA~CE TO S.MEC.J~B.OGPA'1 

RESULTS TO DATE PR rr-VIR I L YIN AT~'OSPHER I C STUD I ES -

NE\-! RfillIATIVE TPJJ'JSFER CODE HAS BROAD APPLICABILITY 

r'IULTIPLE VIS-! Al'iGLE OPTICAL DEPTH DETERi'·HNATION TECHfilQUE -

RETR I E\!ES FUNDA!-~ENTAL ATI-'QSPHER I C PROPERTY USEFUL FOR CORRECT HJG 

SURFACE nEASUREvENTS 

lEAF (',()N I Q!!ETRY 'III LL DE USEFUL TO CN-lOPY r''ODELLERS 

PoSSIBLE APPLICATI()"l OF 3-D RADIATIVE TRANSFER ALGORITHI"'S TO CO'-iPUTATIOf'I 

OF LI GHT SCA TIER I NG IN PLANT CANOP I ES 

D. J. DINER 

QQ 

'i <~ 

~ r·) 0:"; 

~ ~~ cC.\ "1 

C ~. 2 ~.~:~ 

:18 
I 

~ 

~>; 

t~ .AIb 

N 

N 

I.D 

PART! C I Pt>NTS 

DAVID J. DINERJ JPL (PRitiCIPAL U,VESTIGl\TOR) 

JOHN V. r'v'\RTONCHI K, JPL (CO - INVEST I G}\TOR ) 

\~ I LL J N" D. Sr'ffTHE J JPlJUCLA (CO - I t'<'VEST I GATOR) 

CHARL~S ~ESSCl1J UCU\ (Grv'{)U/\T~ STUDe;T) 

PUBLI CAT! OOS 

AT1'OSPHERIC TRANSFER OF RADiATION N30VE m INHOI'OGEfJ::OUS NON-lA"''J3ERTIAN 

SURFACE, 1. THEORY 

(To APPEAR I!~ JQSRT) 

ATI'OSPHERIC TRJ\NSFER OF RADIATION ABOVE AN WI-:ot·'OGENEOUS NON-LAt-lBERTJAN 

SURFACE. I I. COr-'PUTATIONAL CONSIDEPATlor-lS AND RESULTS. 

( SUB!·jI TIED TO JQSRT) 

THREE-DIr'1ENSIONAL RADIATIVE TRANSFER USING A FOURIER TRANSFORr-i ~v\TRIX 

OPEPATOR 1·1ETHOD. 

(IN PREPARATIOrn 

D. J, DWER 
h':~--",""jj ~ 

~' " " ,~Jt %, 

I 

I 

, , 

I 

~I', . 

,. 

N 

W 

o 

>-

~ 

Vl 

~ 

LU 

~ 

Z 

¢ AR "'b-4(~~,Q'0«': ",g~; if e M.J:;pP ..*,& 

. \ 

0.15 

0.14 

0.13 

0.12 

0.11 

0.10 

0.09 

0.08 

0.07 

0.06 

0.05 

0.04 

0.03 

0.02 

0.01 

DISTANCE FROM BOUNDARY (km) 

:;a 4 Mj.t4& ~ ~;;..."".t ih?l¥iji ~1;, '\ ::;t"?;i").SA.2C$~"1.~'}$.,.>&~'" 

.. 
" 

OFF-NADIR PUSH-BROOM Ilv\AGING 

THROUGH ATMOSPHERE 

\ 1/ 

- - ':::::D "-

- - / 1\""'-

Il = cos e 

111127r Fe-T/P.wIREcn + 1T 0 0 Id (x, p." (j>')P(X,p., p.',qr(j>') III dp.', d<t>' 

+ D (x, J1, (j» 

+ N (xl 

WI FFUSE) 

(NOI SE) 
N 

W 

N 

II '"l 

nr;;:; _ 

1;1(~ DETERMINATION OF ATMOSPHERIC OPTICAL DEPTH 

• COMPUTE POWER SPECTRUM VS. SPATIAL FREQUENCY 5 

• Surl1 OVER FREQUENCY TO 1'111 NI MI ZE UNCORRELATED CROSS TERMS 

• RESTRICT TO HIGH SPATIAL FREQUENCIES SUCH THAT D

5

··O 

_.,_ .. _, 

., 

.. -r/J, 

e I, (p A) + 5 . y ..• 

• OBTAIN !\iEASURUliENTS OF SM1E SWATH AT 2 VIEW ANGLES: PI .)J. + ~P AND ilZ 'P-~P 

• TAKE RATIO AND lOGARITHtvl. FOR Sl\iALL ':'p: 

... ~ --" --_. -- ~- -

? ;1 in G (P. 0 I 

. is \p. <.)\ - i • ~ p" ;,; • ADDITIONAL TERI\\S 

4. , 

OPT! CAL DEPTH 

j 

DEPENDS ON SURFACE 

.. - ......• -

DEPEND ON CONTRI BUll ON FROtvi 

DIFFUSE RADIATION AND NOISE 

OBTAINED FROil1 

MEASUREi\iEr~TS BIDIRECTIONAL REFLICTANCE DISTRIBUTION 

. . . 
N 

w 

w 

. _________________ """_"""_ ---=....zz= .=== 

I.J..J NON-LAMBERTIAN 

U 

Z 

<t 

f2.0 (TRUNCATED HENYEY-

~ 1. 8 

u.. 

I.J..J 

a:::: 1. 6 

-.J 

<t 

z 1.4 0 

fu 1.2 I.J..J 

0:::: 

-

Cl 1.0 

c:c 

Cl 0.8 I.J..J 

N 

-.J 

« 0.6 :E 

a:::: 

0 

z 0.4 

0.2 

GREENSTEI N), 

--------

80 60 40 20 

--------;t---

LAMBERTIAN 

/ 

/ 

o 20 40 60 80 

VI EWI NG ANGLE (degrees) 
/ 

/ 

; 

. 

. i 

.., II 

_r~:~~. 

di-;';:" - U 

-\u.. 

0.50 

0.45 -

A 0.40 

0.35 -

0.30 r1 

I 

9 

! . 

I 

, 

RADIANCE VS. POSITION 

n 

u 

A 

L.J Y 

100 fllETERS IPIXEL 

NON-LAMBERTIAN SURFACE 

! I I 

17 25 33 

I 

I 

41 

PIXEL NUMBER 

n 

A n A' 

VIEWI NG ANGLE :: 76.3° 

AZIMUTH:: 0° 

OPTICAL DEPTH = 0.2 

1 

49 58 

. ! . 

I 

65 
• • 

N 

W 

{YI 

t 

{, 

~ 

lAMBERTIAN SURFACE 

0.4 I I I I 1 I 

TRUE i = 0.2 

\ , 

, 

I 

Q3~ -

r 

o. 2 - - , - I ----1- - - - - - f - - - - - - -<> t ------'1 ----

... 0.1 >- -

.. SNR = 100 (NEAR = 0.01) 

0.0 r- • SNR = 1000 (NEAR = 0.001l -

-0.1 r- 64 PI XELS I N SCAN - * * 

7" = TS (WAVENUM BERS 20-63 I NCLUDED I N MEAN) 

-O.2~~----~I--~I------_~I--~I----_I~--_~I--~I------~ 

1.0 0.9 0.8 O. 1 O. 6 O. 5 0.4 0.3 O. 2 

J1 
i 

\ 

. 

,; 

j. 

! 

! 

, . 

.J 

N 

W 

~ 

G . 

0;"";";1: ... ---' )0 ~ • --.......' 

if;:';~ - lJ 

, 

, 

/ 

NONlAMBERTIAN SURFACE 

0.51 

I SNR = 1000 

0.4[ 

0.3 

,.,. 2 3 

T = T + all + bll 

I 1> = 1800 .-....--__ 1: 

" I .. -f- 0.2 r - - - - - - - ~-- - - - --

O. 1 TRUE -r :: 0.2 

64 PI XELS I N SCAN .. - ::: 

T = TS (WAVENUMBERS 20-63 INCLUDED 'N MEAN) O. 0 

0.8 O. 7 0.6 0.5 0.4 0.3 0.2 0.1 

/ 

0.0 

/ 

/ 
J L REQUIREMENTS OF OBSERVATIONAL SYSTEM 

(PUSH-BROON' IMAGER) 

., OFF-NADIR VIE'NING (UP TO .... 75°) 

• HIGH SPATIAL RESOLUTION (TEr'lS OF METERS) 

• HIGH SIGNA L -TO-NOISE RATIO (/ I DO) 

• FORWARD AND AFT VIEWING DESIREABLE 
r 

I 

I 

0..8 

0 

i= 

N ~ 0..6 w 

co w 

U 

Z 

< 

~ 

u 

=.l 

L!- 0..4 

r 5:1 

I • 

0..2 

0.. 00.. 4 0.53 

CAMELLIA lEAF 

INCIDENCE ANGLE • 0° 

0.61 

WAVElENGTH (MICRONS) 

0.8 

I (29.1°) 

r (00) 

0..93 

00 

."'r1 Al 

"'0[,) 

02 o - ~;:. 

.0 'V c: ',-, ~ ;.< r: _oj 

~ ~. ~'.; 
'\ 

r 

111.0. LIST OF PUBLICATIONS AND PRESENTATIONS - SRAEC PROJECT 

239 
111.0. LIST OF PUBLICATIONS AND PRESENTATIONS - SRAEC PROJECT 

Publication List 

The following SRAEC project supported publications are organized according 

to: (1) published refereed journal articles, (2) journal articles "in press" 

(3) prepared journal manuscripts submitted/in review, (4) thesis or dissertation, 

(5) miscellaneous reports, and (6) symposium or conference presented papers or 

proceedings. 

1. Published Journal Articles 

Chuang. S.L. and J.A. Kong, 1983, "Wave scattering and guidance by dielectric 

waveguides with periodic surfaces," Journal of the Optical Society of America, 

Vol t 73, No.5. 

Fung, A.K. and H.J. Eom, 1983, "Effects of a rough boundary surface on polarization of the scattered field from an inhomogeneous medium," IEEE Geoscience and Remote 

Sensing, (IGARSS '82), Vol. AP-21 , No.3, pp. 265-270. 

Grant. I.., V.C. Vanderbilt and C.S.T. Daughtry, 1983, "Measurements of specularly reflected radiation for individual leaves." Agronomy Abstracts 75:12. 

Jin, Y.O. and J.A. Kong. 1983, "Scattering and active remote sensing of atmospheric precipitation," Appl ted Optics, Vol. 22, 2535-2545. 

Karam. M. and A.K. Fung, 1983, "Scattering from randomly oriented circular discs 

with application to vegetation," Radio Science, Vol. 18, No.4, pp. 557-565. 

Kaufman, Y.J. and R.S. Fraser, 1983, "Oifferent atmospheric effects in remote sensing 

of uniform and non-uniform surfaces," Adv. Space Res., 2, 147-155. 

Kimes, D.S. and J.A. Kirchner, 1982, "Irradiance Measurement Errors Due to the 

Assumption of a Lambertian Reference Panel", Remote Sensing of Environment. 

12:141-149. 

Kimes, O.S. and J.A. Kirchner, 1982, "Radiative Transfer Model for Heterogeneous 

3-D Scenes," Applied Optics, 21(22):4119-4129. 

Kimes, D.S. and J.A. Kirchner and J.E. t1cMul'trey III, 1982, "Variation of 

Directional Reflectnace Factors with Structural Changes of a Developing Alfalfa 

Canopy," Applied Optics, 22:3766-3774. 

Kimes, D.S. and J.A. Kirchner, 1983, "Directional Rarliometric Measurements of 

Row-Crop Temperatures." Int. l). Remote Sensing. 4(2):299-311. 

Kimes, D.S., 19B3, "Remote Sensing of Row Crop Structure and Component Temperatures 

Using Directional Radiometric Temperatures and Inversion Techniques." Remote 

Sensing of Environment, 13:33-55. 

240 

i 
Kimes, D.S. and J.A. Kirchner, 1983, "Diurnal Variations of Vegetation Canopy 

Structure," Int. J. Remote Sensing. 4(2):257-271. 

Kimes, D.S., 1983, "Dynamics of Directional Reflectance Factor Distributions 

for Vegetation Canopies." Applied Optics, 22:1364-1372. 

Kimes. O.S •• J.A. Kirchner and W.W. Newcomb, 1983, "Spectral Radiance Errors in 

Remote Sensing Ground Studies nue to Near By Objects." Applied Optics. 22:8-10. 

lang. R.H. and J.S. Sidhu, 1983. "Electromagnetic backscattering from a layer of vegetation: A discrete approach," IEEE Transaction on Geoscience and Remote 

Sensing, Vol. GE-21, No.1. p. 62. 

leVine, D.M., R. Meneghini, R.H. Lang and S.S. Seker. 1983, "Scattering from 

arbitrarily oriented disks in the physical optics regime." J. Opt. Soc. Amer •• 

Vol. 73, p. 1255. 

Norman, J.M. and J.M. Welles. 1983. "Radiative transfer In an array of canopies," ~gron. J •• 75:481-488. 

Paris, J.F., 1983, "Radar backscattering properties of corn and soybeans at 

frequencies of corn and soybeans at frequencies of 1.6, 4.75 and 13.3 GHz," 

IEEE Trans. Geosci. and Remote Sensing, GE-21(3), 392-400. 

Tsang. L. and J.A. Kong, 1983, "Scattering of electromagnetic waves from a half 

space of densely distributed dielectric scatterers." Radio Science. Vol. 18. No.6, 

1260-1272. 

2. Journal ArtiG1es "In Press" 

Badhwar. G.O., "Automatic classification of corn and soybean using Landsat 

data: Part I: Near-harvest crop proportion estimation. Remote Sensing of 

Environment. 

Badhwar, G.O., "Automatic classification of corn and soybean using Landsat 

data: Part II: Early-season crop proportion estimation. Remote Sensing of 

Environment. 

Fung, A.K. and H.J. Eom, "A scatter model for vegetation up to ku-band," Remote 

Sensing of Environment. 

Fung, A.K. and H.J. Eom, "Scattering from a random layer with application to snow, 

vegetation ann sea Ice," IEEE Proceedings - Special Issue of Radiowavc Propagation. 

Henderson, K.E. and G.D. Badhwar, "An initial model for estimating development 

stages from spectral data," Remote Sensing of Environment. 

Jin, Y.O. and J.A. Kong, "Strong fluctuation theory for electromagnetic wave 

scattering by a layer of random discrete scatterers," Journal of Applied Physics. 

Kaufman, Y.J. and R.S. Fraser, "The Atmospheric effect on classification of 

finite fields." Remote SensJ..!.lg of Environment. 

241 

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Kimes, D.S., B.N. Holben, C.J. Tucker and W.W. Newcomb, "Optimal Directional 

View Angles for Remote Sensing r~1ss10ns," Int. J. Remote Sensing. 

Kimes, D.S., W.W. Newcomb, J.B,_ Schutt, P.J. Pinter, Jr., and R.D. Jackson, 

"Directional reflectance f~ctor distributions of a cotton row crops," Int. J. 

of Remote Sensing,. 

Kong, J.A., S. Lin and S.L. Chuang, "Thermal microwave emission of periodic surface," IEEE Transactions on Geoscience and Remote Sensing. 

Lee, J.K. and J.A. Kong, "Dyadic Green's functions for layered anisotropic medium" Electromagnetics. 

Shin, R.T. and J.A. Kong, "Scattering of electromagnetic waves from a randomly perturbed quasi-periodic surface," Journal of Applied Physics. 

Tsang, L., ,).A. Kong and ReT. Shin, "Radiative transfer theory for active remote 

sensing of a layer of non-spherical particles," Radio SCienE!t. 

Ulaby, F.T. and R.P. Jedlicka. "Microwave dielectric Properties of plant materials," 

IEEE Transactions of Geoscience and Remote Sensinq. 

Vanderbilt, V.C., L. Grant, L.L. Biehl and B.F. Robinson, "Specular, diffuse and 

polarized light scattered by two wheat canopies," Applied Optics. 

3. Submitted Journal Manuscripts 

Badhwar, G.D., "Use of Landsat-derived profil e features for Spring small 

grains classification," International Journal of Remote Sensing. 

Diner, D.J. and J.V. Martonchik, "AtmospheriC transfer of radiation above an 

inhomogeneous non-lambertian reflective ground. I. Theory," submitted to 

Journal of Quantitative Spectros~Q~ and Radiative Transfer. 

Diner, D.J. and J.V. Martonchik. "Atmospheric transfer of radiation above an 

imhomogeneous non-lambertian reflective ground. II. Computational considerations 

and results," submitted to J. Quant. Spectre Rad. Transf. 

Kaufman, V.J. t "AtmospheriC effect on spatial resolution of surface imagery," submitted for publication in Applied Optics. 

Kimes, O.S., "Modeling the Directional Reflectance from Complete Homogeneous Vegetation Canopies with Various Leaf Orientation Distribution," Journal of 

the Optical Society of America, in review. 

Kimes, D.S., \~.W. Newcomh, C.J. Tucker, I.S. Zonneveld, W. Van Wijngaarden, 

G.F. Epema, and J. DeLeeun. "Directional Reflectance Factor Distributions for 

Cover Types of Northern Africa in NOAA 7/8 AVHRR Bands 1 and 2," Remote Sensing 

of Environment, in review. 

Randolph. M.H., "A RTE phase function description of vegetation canopies," 

submitted to IEEE Trans. Geose. and Rem. Sense 

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Vanderbilt, V.C. "Measuring plant canopy structure," submitted to Photogrammetric 

Engineering and Remote Sensing. 

4. Thesis and Dissertation 

Franklin, J., 1983, "An empirical study of the spatial pattern of coniferous 

trees," M.A. Thesis, Univ. of California, Santa Barbara. 

Randolph, M.H., 1983, "A radiative transfer equation/phase function approach 

to vegetation canopy reflectance modeling," Ph.D. Thesis, Colorado State University, 

Ft. Collins, CO. 

5. Miscellaneous Reports 

Al exander. Land G.D. Badhwar, 1983, "Sail canopy model Fortran software, II 

LEMSCO-19867. 

Helmer, D. J. Krantz, M. Tompkins. and G.D. Badhwar, 1983, "User guide for the 

extraction of Landsat spectral and agronomic data," AgRISTARS Document JSC-18598. 

Helmer, D., J. Krantz, M. Kinsler, M. Tompkins and G.D. Badhwar. 1983, "Composition and assembly of a spectral and agronomic data base for 1980 spring small grain 

segments," AgRISTARS Document. 

Helmer, D., J. Krantz, M. Kinsler, M. Tompkins and G.D. Badhwar. 1983. "Argentina 

spectral rlata base," AgRISTARS Document. 

Shin, R.T. and J.A. Kong, 1983. "Emissivity of a blQ-layer random medium with 

anisotropic correlation function." Technical Report No. EWT-RS-41-8303. MIT. 

6. Symposia and Conference 

Allen. C.T. and F.T. Ulaby. 1984. "Modeling the polarization dependence of the 

attenuation in vegetation canopies." to be presented at the 1984 International 

Geoscience and Remote Sensing Symposium (IGAR~S '84). Strasbourg, France. 

Fraser, R.S. and Y.J. Kaufman, 1983, "The relative importance of aerosol scattering 

and absorption in remote sensing." Fifth Conference on Atmosphere Radiation, 

Baltimore, 110. 

Jedlicka, R.P. and F.T. Ulaby, "Measurements of the MicrowalleOielectric and 

Attenuation Properties of Plants," National Radio Science Meeting (URSI Commission 

F). University of Colorado. Boulder. CO. 

Jin, Y.O. and J.A. Kong. 1983, "Mie scattering of electromagnetic waves by 

precipitation," Optical Society of America Topical r~eetin~1 on Optical Techniques 

for Remote Probing of the Atmosphere. Lake Tahoe. Nevada. 

Karam. M. and A.K. Fung, 1983. "Scattering from randomly oriented scatterers 

of arbitrary shape in the low-frequency limit with application to vegetation," Digest of IGARSS'83, IEEE 1983 International Geoscience and Remote Senslrl!;J 

Symposium. 

243 

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Kaufman, V.J., T.~4. Brakke and Eo Eloranta, 1983, "Field experiment to measure 

the radiative characteristics of a hazy atmosphere," Fifth Conference on Atm. 

Rad., Baltimore, MD. 

Kong. J.A., 1982, "Theoretical models for microwave remote sensing of vegetation 

and soil moisture," AgRISTARS Symposium. Houston, TX. 

Kong, J.A., S.L. Lin, S.L. Chuang, andk R.T. Shin, 1983, "Remote sensing of 

soil moisture and vegetation, URSI SXmposfum, Boulder, CO. 

Lang, R. and D.M. LeVine, 1%3~ "Backscattering from a vegetation layer--a multiple 

component model, National Radio Sci. Meeting, Boulder, CO. 

Lang, R.H •• A. Schneider and S. Seker, 1983, "Mean wave propagation in a trunk 

forest," National Radio Science t·leeti!!.9., Houston, TX. 

Lang, R.H •• 1984, "Back scattering from a vegetation layer: Coherent and incoherent 

models," Micro\'1ave Signatures in Remote Sensing, URSI Symposium, Toulouse, France. 

Paris, J.F., 1983, "Effects of vegetation canopy structure on microwave backscatter," 

National Radio Sci. Meeting, Boulder, CO. 

Paris, J.R., 1983, "On the use of polarized radar measurements for vegetation studies," 

International Geosci. and Remote SenSing Symp., San Francisco, CA. FPS-S. 

Shin. R.T. and J.A. Kong. 1983, "Thermal microwave emission from a scattering 

medium with rough surfaces," URSI Symposium, Boulder. CO. 

Teillet, P.H., R. Brown, J.A. Smith and G. Federejeus, 1983, "Reflectance model 

studies," at the fCRS International Col log. on Spectral Sign. in Remote Sens., 

Bordeaux. France. 

Tsang, L. and J.A. Kong, 1983, "Scattering of electromagnetic waves from a 

half-space of densely distributed die1ectdc scatterers, IEEE/APS Symposium 

and URSI Meetin~, San FranCiSCO, CA. 

Tsang, L. and J.A. Kong. 1983, "Theory of microwave remote sensing of dense medium," 

IEEE/GRS Symposium and URSI Meeting. San Franscico, CA. 

U1aby, F.T., R.P. Jedlicka and C.T. Allen. 1984, "Measuring and modeling the 

dielectric and attenuation properties of vegetation," to be presented at the 

International Un'jon of Radio Science Meeting (URSI Commission F), Toulouse, France. 

Ulaby, F.T., 1983, "~1icrowave properties of vegetation canopies: An overview," 

International Colloquium on spectral signatures of objectives in remote senSing, 

BOrdeaux. France. 

Vanderbilt. V.C. and L. Grant, 1983, "Ligh polarization measurements: A method to 

determine the specular and diffuse light-scattering properties of both leaves and 

pl ant canopi es. conference paper presented to the Inter'nat i onal Coll oqui urn on 

SRectral Signatures of Objects in Remote Sensing. Bordeaux. France. 

Vanderbilt. V.C., L. Grant, L.L. Biehl and B.F. RObinson. 1983. "Specular and 

diffuse refl ectance of two wheat canopt es meaured at many vi ew ang1 es. l!l!ernat i ona1 

Union of Radio Science. 

244 
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APPENDIX 

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APPENDIX A 

SRAEC PROJECT 

LIST OF PRINCIPAL INVESTIGATORS 

Or. Gautam Badhwar 

NASA/Lyndon B. Johnson Space Center 

Code SF3 

Houston, TX 77058 

(713) 483-6481 

Dr. David J. Diner 

NASA/Jet Propulsion laboratory Mailstop 183b-365 

4800 Oak Grove Drive 

Pasadena, CA 91109 

fTS 792-6158 

(213)354-6158 

Dr. Robert E. Fraser 

NASA/Goddard Space Flight Center 

Code 915 

Greenbelt, MD 20771 

(301) 344-9008 

Dr. Adrian K. Fung 

University of Kansas Center for Research 

2291 Irving Hill Drive - Campus West 

lawrence. KS 66045 

(913) 864-4832 

Dr. Siegfried A. W. Gerstl 

Theoretical Division. MS-B279 

los Alamos National Laboratory los Alamos, NM 87545 

FTS 843-3876 

(505) 667-3876 

Dr. Daniel S. Kimes 

NASA/Goddard Space Flight Center 

Code 923 

Greenbelt. MD 20771 

(3Dl) 344-4927 

Dr. Jin-Au Kong 

Research Laboratory for Electronics 

Massachusetts Institute of Technology Cambridge, MA 02139 

(61 i) 253-5625 

Dr. Roger H. lang 

Department of Electrical Engineering and Computer Science 

George Washington University 

Washington, DC 20052 

(202) 676-6199 

246 

Dr. R. K. Moore 

University of Kansas 

Center for Research 

2291 Irving Hill Drive - Campus 

lawrence, KS 66045 

(913) 864-4836 

Dr. John M. Norman 

Department of Agronomy 

University of Nebraska 

lincoln. NE 68583 

(402) 472-2847 

Dr. Jack F. Paris 

NASA/Jet Propulsion laboratory Mailstop 183-701 

4800 Oak Grove Drive 

Pasadena. CA 91109 

FTS 792-5673 

Dr. William A. Pearce 

EG&G Washington Analytical Services 

Center Inc. 

6801 Kenilworth Avenue 

Riverdale. MD 20737 

(301) 779-2800 X247 

Dr. James A. Smith 

College of Forestry and National 

Resources 

Colorado State University 

Fort Collins, CO 80523 

(303) 4~1-5420 

ur. Alan H. Strahler 

Hunter College 

Dept. of Geography 695 Park Avenue 

Box 1513 

New York, NY 10021 

(212) 570-5555 

Dr. Fawwaz T. Ulaby 

Director. Remote Sensing Laboratory University of Kansas 

Center for Research, Inc. 

2291 Irving Hill Drive - Campus West 

Lawrence, KS 66045 

(913) 864-4832 

Dr. Vernan C. Vanderbilt 

LARS/Purdue University 

West Lafayette, IN 47907 

(317) 494-6346 or 6305 
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APPENDIX C 

AGENOA 

Second Annual Workshop of the NASA Fundamental Research 

Scene Radiation and Atmospheric Effects Characterization Project 

CSU/Ft. Collins. Colorado 

Monday. January 9 

Welcome 

NASA Perspectives 

Terms and Measurements in the Optical Regime 

Or. Don Dp.ering--Canopy & Soil Measurements 

Dr. John Norman--Leaf ~1easurements and Interpretations Through Modeling 

Terms and Measurements in the Radar/Microwave Regime 

Dr. Jack Pari s 

Terms anrt Concepts in the Atmospheric Sciences 

Dr. Siegfried Gerstl 

Tuesd ay. January 10 

Opt ical Terrain Refl ectance Hodel ing 

Dr. James Smith 

Radar/Micro'f'dVe Model ing Dr. Ad ri an Fung 

Atmospheric Measurements 

Dr. Y. Kaufman 

Model Inversion 

Dr. N. Goel 

Principal Investigator Reports 

A. Fung 

F. Ul aby 

R. K. ~oore (Reza Zoughi) 

R. Lang 

R. F~aser 

Y. Kaufman 

MPRIA Presentations 

R. Heydorn 

A. Strahl er 

l. Schumaker 

Wednesday. January 11 

Principal Investigator Reports D. Diner 

S. Gerstl 

A. Strahler 

11. Batihwar 

D. Kimes 

J. Smith 

J. Norman 

J. Kong 

J. Paris 

V. Vanderbilt 

249 

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5. For optical wavelengths, soil reflectance enhances 

reflectance from vegetated surfaces and has a significant 

effect for leaf area index less than 3. Soil reflectance 

decreases as soil surface irregularities incr.ease. At 

greater look angles, soil irregularities cause less variation 

in soil reflectance than they do at near-nadir look angles. 

A smooth soil surface approximates a Lambertian surface. 

6. For optical wavelengths, the bidirectional reflectance 

distribution function for any given plant varies as a 

function of the diurnal movements of the plant in response to 

external stimuli. 

7. Specular reflection is a significant factor in the 

bidirectional reflectance distribution function of leaves. 

By quantifying and subtracting the specular component, the 

remaining diffuse component in the reflectance distribution 

correlates significantly with leaf moisture content for 

infrared measurements and chlorophyll viability for 

measurements in the red region. 

8. Atmospheric effects on target reflectance include, by nature, 

the adjacency effect, i.e., r~flectance from the ground 

outside the immediate view scattered by the atmosphere into 

the field-of-view of the sensor. Recent results indicate the 

adjacency effect decreases the separability of image field 

classes when one dimension of a field approaches the height 

of the atmospheric aerosol layer above the target. 

9. The use of off-nadir viewing is better for estimating 

atmospheric optical depth from reflectance. 

10. Results show a correlation b~tw~en brightness and atmospheric 

optical depth over full cano~y coverage. 

Some conclusions and recommendations evolved from the workshop 

discussions which are relevant to our future program direction. 

Briefly, these include: 

(1) The measurement of plant water content provides a common 

denominator for microwave modeling and optical modeling of 

vegetation canopies. Plant water content determines the 

dielectric properties influencing microwave backscatter and 

the degree of,absorption/reflectance in the infrared and is 

a function of the amount of live plant matter, the 

biophysical pRrameter for which information is sought 

through these techniques. 

(2) An experiment designed to provide a common data set to all 

optical and microwave investigators where both field . measurements and remotely sensed measurements in all 

wavelength regimes are acquired simultaneously would be 

highly desirable at this stage of the research program. 

252 
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(3) Based on the progress of the investigations to date, it is 

an appropriate time to direct research towards the 

development of techniques for combining info!:lIIation learned 

about the target and the atmosphere from the rleparate 

wavelength regions. We should also advance our models from 

single plant canopy studies to field canopy studies to 

improve the characterization of scene radiation. 

(4) Future program initiatives should encourage coordination of 

interests between the scene radiation (SRAEC) group and the 

mathematical pattern recognition (MPRIA) group to foster 

complementary research. For example, image representation 

techniques developed independently by the MPRIA effort 

should now be tested for their use in validating canopy 

radiance models developed by the SRAEC effort and applied 

within the context of an image scene. 

The workshop was an extremely effective mechanism for stimulating 

research interests and sustaining a thread of commonality among 

the diverse investigation objectives. A list of workshop 

participants is enclosed. A workshop proceedings will be 

published within a month. 

M. Kristine Butera 

Enclosure 

cc: 

EE/Tilford 

EE/Arnold 

EE/Hogg 

EE/Settle 

EE/Trichel 

EE/Tuyahov 

EE/Agal:wal 

EE/l~atson 

GSFC/923/Murphy 

GSFC/923/0cering 

JSC/SG3/Heydorn 

253 

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End of Document