BOREAS TE-10 Leaf Optical Properties for SSA Species

Summary

The BOREAS TE-10 team collected several data sets in support of its efforts to 
characterize and interpret information on the reflectance, transmittance, gas 
exchange, oxygen evolution, and biochemical properties of boreal vegetation.  
This data set describes the spectral optical properties (reflectance and 
transmittance) of boreal forest conifers and broadleaf tree leaves as measured 
with a Spectron Engineering SE590 spectroradiometer at the SSA OBS, OJP, YJP, 
OA, OA-AUX, YA-AUX, and YA sites.  The data were collected during the growing 
seasons of 1994 and 1996 and are stored in tabular ASCII files.

Table of Contents

  1. Data Set/Model Overview
  2. Investigator(s)
  3. Theory of Measurements
  4. Equipment
  5. Data Acquisition Methods
  6. Observations
  7. Data Description
  8. Data Organization
  9. Data Manipulations
 10. Errors
 11. Notes
 12. Application of the Data Set/Model
 13. Future Modifications and Plans
 14. Software
 15. Data Access
 16. Output Products and Availability
 17. References
 18. Glossary of Terms
 19. List of Acronyms
 20. Document Information

1. Data Set Overview

1.1 Data Set Identification

BOREAS TE-10 1994 and 1996 Leaf Optical Properties for SSA Species

1.2 Data Set Introduction

This data set describes the spectral optical properties (reflectance and 
transmittance) of included leaves and needles from boreal forest tree species as 
measured with a Spectron Engineering SE590 spectroradiometer at the BOReal 
Ecosystem-Atmosphere Study (BOREAS) Southern Study Area (SSA) Old Black Spruce 
(OBS), Old Jack Pine (OJP), Young Jack Pine (YJP), Old Aspen (OA), Old Aspen 
Auxiliary (OA-AUX), Young Aspen Auxiliary (YA-AUX), and Young Aspen (YA) sites.

1.3 Objective/Purpose

The purposes of this work were to:

1) Obtain a canopy profile of needle spectral optical properties.

2) Examine interspecific and interseasonal differences in these parameters.

3) Correlate physiological processes at the leaf/needle level with optical 
measurements amenable to remote sensing.

4) Examine the relationships between the physiological parameters, especially 
photosynthesis and conductance rates, and the optical parameters (fraction of 
Absorbed Photosynthetically Active Radiation (fAPAR) and spectral vegetation 
indices (SVI)).

5) Parameterize the canopy-level radiative transfer and physiological models 
utilized in landscape analyses by other investigators.

1.4 Summary of Parameters and Variables

Hemispherical reflectance (R) and transmittance (T) factors were measured for 
needles of various growth years and individual leaves illuminated at near-normal 
incidence measured using an external light source and LI-COR LI-1800-12 
integrating sphere attached to a Spectron Engineering SE590 spectroradiometer.

1.5 Discussion

Hemispherical reflectance and transmittance factors of individual needles (ages: 
current year, previous year, 2 years ago, and up to 5 years ago growth) and 
broadleaf tree leaves (current year) were measured using a LI-COR LI-1800-12 
Integrating Sphere attached to a Spectron Engineering SE590 spectroradiometer, 
and the image analysis system. The SSA sites studied were OBS, OJP, YJP, OA, OA-
AUX, YA-AUX, and YA.

1.6 Related Data Sets

BOREAS TE-10 Gas Exchange Data
BOREAS TE-12 Leaf Optical Data for SSA Species

2. Investigator(s)

2.1 Investigator(s) Name and Title

Dr. Elizabeth Middleton
Project Scientist

Dr. Joseph Sullivan
Assistant Professor

2.2 Title of Investigation

CO2 and Water Fluxes in the Boreal Forest Overstory: Relationship to fAPAR and 
Vegetation Indices for Needles/Leaves

2.3 Contact Information

Contact 1:
Stephen S. Chan
Biospheric Sciences Branch
NASA GSFC
Greenbelt, MD
(301) 286-2386
sailun@ltpmail.gsfc.nasa.gov

Contact 2:
Dr. Elizabeth Middleton
Biospheric Sciences Branch
NASA GSFC
Greenbelt, MD 
(301) 286-8344
(301) 286-0239 (fax)
betsym@ltpmail.gsfc.nasa.gov

Contact 3:
Andrea Papagno
Raytheon STX Corporation
NASA GSFC
Greenbelt, MD
(301) 286-3134
(301) 286-0239 (fax)
apapagno@pop900.gsfc.nasa.gov

Contact 4:
Shelaine Curd
Raytheon STX Corporation
NASA GSFC
Greenbelt, MD 
(301) 286-2447
(301) 286-0239 (fax)
shelaine.curd@gsfc.nasa.gov

3. Theory of Measurements

Leaves, needles, and bark are canopy elements that are important in scattering 
radiation in boreal forest vegetation (Norman and Jarvis, 1974).  Needle and 
bark properties can vary considerably depending on age and height in the canopy; 
elements deep in the canopy may be covered with algae and fungi, and shade-
induced effects on shoot development may exist (Norman and Jarvis, 1974; Smith 
and Carter, 1988).  In the near-infrared portion of the electromagnetic 
spectrum, little radiation is absorbed; thus, scattering by canopy elements will 
be significant.  In contrast, leaves and needles absorb a large portion of PAR 
(Daughtry et al., 1989; Williams, 1991).  Conifer needles absorb more PAR than 
deciduous leaves; twigs, especially the current year's growth, also absorb PAR 
(Williams, 1991).  Thus, the scattering component of PAR may be small except in 
sparse canopies with high underlying surface albedo.

4. Equipment

4.1 Sensor/Instrument Description

The Spectron Engineering SE590 is a portable battery-operated spectroradiometer 
consisting of a CE500 data analyzer/logger controller, CE390 spectral detector 
head, and an external battery charger/power supply.  The CE500 is a self-
contained microprocessor-based controller that processes the signal from the 
detector head, amplifying and digitizing it with 12-bit resolution.  For each 
spectral scan, the controller actuates the CE390 shutter, measures and stores 
the dark current, calculates optimum integration time, acquires the spectrum, 
and automatically subtracts the noise for all 256 spectral elements.  Each scan 
was recorded individually.  The entire 12-bit binary spectrum is stored in a 
double-precision register until it is transmitted through the RS-232C port.  The 
spectral detector head uses a diffraction grating as the dispersive element; the 
spectrum is imaged onto a 256-element photodiode array.  Each element integrates 
simultaneously, acquiring the spectrum in a fraction of a second.  The 
interconnect cable from the spectral head to the controller couples the spectral 
signals to the controller and the timing and control signals to the detector 
head.  A shutter in the detector head, operated by the controller, closes the 
light path for dark current measurements.  For further information, consult the 
SE590 operating manual.  The serial numbers for the SE590s used in 1994 and 1996 
are 2071 and 1051, respectively.

The LI-COR LI-1800-12 integrating sphere is an instrument for collecting 
radiation that has been reflected from or transmitted through a sample material.  
An external light source illuminates a spot on the sample.  A standard light 
source (11.4-mm diameter) and a modified light source that restricts the 
illumination spot size (3.5-mm x 11-mm) were used.  The lamp used in the 
external light source is a 6-Volt 10-Watt glass-halogen.  For a further 
description, see the LI-COR Integrating Sphere Instruction Manual.  Serial 
Number 2071 was used in 1994, and 1051 was used in 1996..

An image analysis system was used to measure the gaps between sample elements 
(e.g., needles) when a sample did not fill the entire integrating sphere sample 
port or a single sample element was too narrow to be completely encompassed by 
the modified light source.

The image analysis system included a black-and-white (B/W) charge-coupled device  
(CCD) video camera, a monochrome frame-grabber board, an IBM PC-compatible 
laptop unit with docking station, a light table, and a video monitor display 
with full 640 x 480 pixel2 spatial resolution and 256 gray levels.  This system 
was used to determine gap fraction per sample, defined as the ratio of needle 
gap area to that of the total illuminated area within the aperture (round or 
slitted) of a precision reference template placed on a light table as viewed 
from above by the camera.  The template, a small metal disk, was viewed alone 
and the area measured. then the template was viewed with the sample on top of it 
and the area left uncovered by the needles was measured. so the ratio of the gap 
area to total area makes the gap fraction.  Software for image capture was 
"Computer Eyes/RT" (Digital Vision, Inc., Dedham, MA) and for processing was 
"Mocha" (SPSS, Inc., Chicago, IL).  Appropriate calibration procedures were 
used: a) for the area of a standard template, each sample; b) for the stray 
light/dark current scans per measurement set; and c) for the wavelength 
stability of the radiometer and its spectral radiance coefficients.  

A monochrome frame-grabber board (UM-08128-B) was used to input the signal from 
the camera into an IBM-compatible laptop computer with a docking station. SPSS 
Inc.s software Mocha ver. 2.0 was used to measure the areas of the incident 
light source beams and gaps.  The display monitor was an IBM VGA with 640- by 
480-pixel resolution.

4.1.1 Collection Environment

The vertical profile of the canopy was divided into three layers: top, middle, 
and bottom. Measurements were taken at the SSA OBS (Picea mariana), OJP (Pinus 
banksiana and Apocynum androsaemifolium), YJP (Pinus banksiana), YA (Populus 
tremuloides and Corylus cornuta Marsh), OA (Populus tremuloides and Corylus 
cornuta Marsh), OA-AUX (Populus tremuloides and Corylus cornuta Marsh), and YA-
AUX (Populus tremuloides and Corylus cornuta Marsh and Picea glauca). At the 
OBS, OA, OA-AUX, and OJP sites, sample collection was made from canopy access 
towers constructed onsite by BOREAS staff. At the YJP, YA, and YA-AUX sites, 
collection was accomplished from the ground. Collection of hazelnut understory 
was also accomplished from the ground.  In 1994, data were obtained during three 
discrete measurement periods (1 to 2 days each period) designated by BOREAS as 
Intensive Field Campaigns (IFCs) (IFC-1, -2, -3).  In 1994, these IFCs were 
selected to measure parameters at bud breaks and leaf expansion (24-May to 12-
Jun), during midsummer or peak growing season (26-Jul to 08-Aug) and at the 
onset of dormancy or senescence in autumn (30-Aug to 15-Sep). In 1996, 
collection dates did not necessarily coincide with any official IFCs.  In 1994, 
the samples were measured individually.  The period of measurement in 1996 was 
during July.  On collection/observation day 14-Jul-1996, the 1992 and 1993 
samples were combined and the 1994 and 1995 samples were combined.  Branch tips 
measured were excised from the trees and sealed in plastic bags with moist 
towels.  After collection, samples were refrigerated until the measurements were 
conducted in the room-temperature field laboratory.  

4.1.2 Source/Platform

During these measurements, the spectroradiometer and the integrating sphere were 
mounted on a tripod in the laboratory.

4.1.3 Source/Platform Mission Objectives

Not applicable.

4.1.4 Key Variables

Adaxial and abaxial spectral reflectance and transmittance. For both broadleaves 
and conifer needles, the designation of foliar surfaces as either adaxial 
(dorsal or upper) or abaxial (ventral or underside) is made on an anatomical 
basis (Esau, 1977).  For broadleaves (both dicots and monocots), the adaxial 
(dorsal) surface is the one adjacent to the palisade mesophyll layer, and the 
abaxial (ventral) surface is adjacent to the spongy mesophyll layer.  For 
conifers, the adaxial surface is the flat (or less curved) facet whose surface 
lies closest to the xylem at the needle core, while the abaxial surface is the 
typically more curved and opposite facet whose surface lies closest to the 
phloem at the needle core.

4.1.5 Principles of Operation

The SE590 spectral detector head uses a diffraction grating as the dispersive 
element; the spectrum is imaged onto a 256-element photodiode array.  Each 
element integrates simultaneously, acquiring the spectrum in a fraction of a 
second.

The LI-COR LI-1800-12 integrating sphere is an external integrating sphere, 
which means that the sample is external to the sphere; when the sample is in 
place, a small part of the sample actually makes up part of the sphere wall.  
For further information, see the LI-COR 1800-12 Integrating Sphere Instruction 
Manual.

The CCD camera transmits a signal to the frame-grabber board, which translates 
the intensity of each pixel to a gray scale from 0 (black) to 255 (white) 
levels.  The Mocha software program was set up to count the number of pixels in 
a defined area of interest for a range of gray scales that represent the "white" 
gaps between the sample elements.  The white threshold was determined by 
adjusting the threshold so that a standard size (area) reference template 
actually registered the correct area.

4.1.6 Sensor/Instrument Measurement Geometry

All instrumentation took place under laboratory conditions.  The SE590 was 
mounted on top of the LI-COR LI-1800-12 integrating sphere.  A tripod was 
attached to the support connecting the SE590 and integrating sphere.  A modified 
external light source with a slitted beam (3.5 mm x 11 mm) was used to 
illuminate narrow samples and associated reference.  A standard external light 
source with a circular beam (11.4-mm diameter spot size) was used to illuminate 
all other samples and associated reference.  The light source was kept in a 
horizontal position according to integrating sphere manual requirements.

4.1.7 Manufacturer of Sensor/Instrument

Spectron Engineering SE590 Spectroradiometer:
Spectron Engineering, Inc.
25 Yuma Court
Denver, CO 80223
(303) 733-1060

LI-COR LI-1800-12 Integrating Sphere:
LI-COR, Inc.
Box 4425
Lincoln, NE 68504
(402) 467-3567

B/W CCD WVBL200 Video Camera
Panasonic 

MOCHA Software (ver. 2.0):
SPSS, Inc.
233 S. Wacker Drive
11th Floor
Chicago, IL 60606-6307
1 (800) 543-2185
1 (800) 841-0064 (fax)

4.2 Calibration

Appropriate calibration procedures were used: a) for the area of a standard 
template, each sample; b) for the stray light/dark current scans per measurement 
set; and c) for the wavelength stability of the radiometer and its spectral 
radiance coefficients.

4.2.1 Specifications

Each SE590 has a unique wavelength associated with each of its 252 bands.  A 
cubic spline interpolation was applied to the 252 bands to standardize the 
wavelengths to every 5 nm from 400 to 1000 nm, so that wavelength-to-wavelength 
comparisons can be made among SE590s.

4.2.1.1 Tolerance

None given.

4.2.2 Frequency of Calibration

The SE590s were calibrated against Hg and Ar vapor lamps before and after each 
IFC or collection session.

4.2.3 Other Calibration Information

For 1994:

Wavelengths, in nanometers, and their corresponding channels (ch), used for data 
reduction.

Wavelength Characterization (nm) for BOREAS Terrestrial Ecology (TE)-10 SE590 on 
31-May-1994 by NASA GSFC (SE590 serial number 2071):

 channel wavelength      ch. wavelength     ch. wavelength     ch. wavelength
 ------- ----------      --- ----------     --- ----------     --- ----------
      1  359.6461        64  534.7401       127   721.4871     190   919.8871    
      2  362.3343        65  537.6133       128   724.5453     191   923.1302
      3  365.0255        66  540.4895       129   727.6064     192   926.3763
      4  367.7196        67  543.3686       130   730.6705     193   929.6253
      5  370.4167        68  546.2506       131   733.7374     194   932.8773
      6  373.1167        69  549.1355       132   736.8074     195   936.1322
      7  375.8196        70  552.0235       133   739.8803     196   939.39
      8  378.5255        71  554.9143       134   742.9561     197   942.6508
      9  381.2343        72  557.8081       135   746.0348     198   945.9145
     10  383.9461        73  560.7048       136   749.1165     199   949.1812
     11  386.6607        74  563.6044       137   752.2011     200   952.4508
     12  389.3783        75  566.507        138   755.2886     201   955.7233
     13  392.0989        76  569.4125       139   758.3791     202   958.9987
     14  394.8224        77  572.321        140   761.4726     203   962.2771
     15  397.5488        78  575.2324       141   764.5689     204   965.5584
     16  400.2782        79  578.1467       142   767.6682     205   968.8427
     17  403.0105        80  581.064        143   770.7704     206   972.1299
     18  405.7457        81  583.9841       144   773.8756     207   975.42
     19  408.4838        82  586.9073       145   776.9837     208   978.7131
     20  411.225         83  589.8334       146   780.0947     209   982.0091
     21  413.969         84  592.7624       147   783.2087     210   985.3081
     22  416.716         85  595.6943       148   786.3256     211   988.6099
     23  419.4659        86  598.6292       149   789.4455     212   991.9147
     24  422.2187        87  601.567        150   792.5683     213   995.2225
     25  424.9745        88  604.5077       151   795.694      214   998.5332
     26  427.7332        89  607.4514       152   798.8226     215   1001.846
     27  430.4949        90  610.3981       153   801.9542     216   1005.163
     28  433.2595        91  613.3476       154   805.0887     217   1008.482
     29  436.027         92  616.3001       155   808.2262     218   1011.805
     30  438.7975        93  619.2555       156   811.3666     219   1015.13
     31  441.5708        94  622.2139       157   814.5099     220   1018.459
     32  444.3472        95  625.1752       158   817.6562     221   1021.79
     33  447.1265        96  628.1394       159   820.8054     222   1025.124
     34  449.9087        97  631.1066       160   823.9576     223   1028.461
     35  452.6938        98  634.0767       161   827.1126     224   1031.801
     36  455.4819        99  637.0498       162   830.2706     225   1035.144
     37  458.2729       100  640.0258       163   833.4316     226   1038.49
     38  461.0668       101  643.0047       164   836.5955     227   1041.839
     39  463.8637       102  645.9865       165   839.7623     228   1045.191
     40  466.6636       103  648.9713       166   842.9321     229   1048.545
     41  469.4663       104  651.959        167   846.1048     230   1051.903
     42  472.272        105  654.9497       168   849.2804     231   1055.264
     43  475.0806       106  657.9433       169   852.4589     232   1058.627
     44  477.8922       107  660.9398       170   855.6405     233   1061.994
     45  480.7067       108  663.9393       171   858.8249     234   1065.363
     46  483.5241       109  666.9417       172   862.0123     235   1068.735
     47  486.3445       110  669.9471       173   865.2026     236   1072.111
     48  489.1678       111  672.9553       174   868.3958     237   1075.489
     49  491.9941       112  675.9665       175   871.592      238   1078.87
     50  494.8233       113  678.9807       176   874.7911     239   1082.254
     51  497.6554       114  681.9978       177   877.9932     240   1085.641
     52  500.4904       115  685.0178       178   881.1982     241   1089.031
     53  503.3284       116  688.0408       179   884.4061     242   1092.424
     54  506.1693       117  691.0667       180   887.617      243   1095.82
     55  509.0132       118  694.0955       181   890.8307     244   1099.219
     56  511.86         119  697.1272       182   894.0475     245   1102.62
     57  514.7097       120  700.162        183   897.2672     246   1106.025
     58  517.5624       121  703.1996       184   900.4898     247   1109.432
     59  520.418        122  706.2402       185   903.7153     248   1112.843
     60  523.2766       123  709.2837       186   906.9438     249   1116.256
     61  526.138        124  712.3301       187   910.1752     250   1119.673
     62  529.0024       125  715.3795       188   913.4095     251   1123.092
     63  531.8698       126  718.4318       189   916.6468     252   1126.514

For 1996:

Wavelengths, in nanometers, and their corresponding channels, used for data 
reduction.

Wavelength Characterization (nm) for BOREAS TE-10 SE590 on 19-May-1996 by NASA 
GSFC (SE590 serial number 1051):
ch.   wavelength   ch.   wavelength    ch.   wavelength    ch.   wavelength
---   ----------   ---   ----------   ---    ----------    ---   ----------
 1    360.1405     64    535.3193      127   722.5816      190   921.0249
 2    362.9569     65    537.9889      128   725.6702      191   923.5632
 3    366.4362     66    541.1645      129   727.8751      192   926.5912
 4    369.2162     67    543.9707      130   730.7025      193   931.4050
 5    370.6827     68    546.2993      131   734.3596      194   934.4142
 6    373.5435     69    549.7904      132   737.8586      195   936.2727
 7    376.1163     70    552.4260      133   740.2515      196   939.8535
 8    378.7204     71    555.3782      134   743.3154      197   942.9930
 9    382.4035     72    558.2172      135   747.1053      198   947.1103
10    385.6378     73    561.9365      136   750.4144      199   949.8366
11    387.9678     74    564.9579      137   752.2017      200   952.7264
12    389.4546     75    567.6845      138   755.3228      201   956.8641
13    392.1760     76    569.5253      139   759.0406      202   959.8645
14    395.1965     77    573.2707      140   763.4584      203   963.1107
15    397.7772     78    575.2397      141   764.6765      204   967.0283
16    400.4819     79    579.1161      142   768.4408      205   969.6374
17    403.0910     80    581.6889      143   771.3158      206   973.4302
18    406.1777     81    585.3271      144   774.3496      207   976.1201
19    409.4557     82    587.1065      145   777.1546      208   978.8361
20    411.9212     83    590.0847      146   781.1493      209   983.2477
21    414.6198     84    594.0846      147   784.5945      210   985.5351
22    417.5016     85    596.4154      148   786.4127      211   990.1134
23    420.2417     86    598.7330      149   789.8508      212   993.0454
24    423.4704     87    601.8935      150   792.8632      213   995.8198
25    426.7591     88    604.8884      151   795.7158      214   999.0036
26    429.4513     89    608.6492      152   800.2796      215  1002.6315
27    430.5617     90    610.9973      153   802.2711      216  1005.7451
28    433.8799     91    613.6475      154   805.7332      217  1009.4871
29    436.2423     92    617.6015      155   809.1172      218  1013.0036
30    439.8257     93    619.5585      156   811.5326      219  1015.9353
31    442.8191     94    622.6438      157   815.6465      220  1019.1051
32    445.1902     95    625.6931      158   817.9621      221  1021.9994
33    447.2221     96    629.0358      159   821.7254      222  1025.8942
34    450.4475     97    631.4492      160   824.7415      223  1028.6137
35    453.6972     98    634.8992      161   828.5148      224  1032.6801
36    455.8462     99    637.0956      162   830.6718      225  1035.4542
37    458.9906    100    640.1055      163   834.1582      226  1038.6841
38    462.2092    101    643.4478      164   837.6238      227  1042.0068
39    465.0868    102    646.6421      165   840.2246      228  1045.3784
40    467.5963    103    649.7776      166   842.9457      229  1049.1268
41    469.4833    104    651.9899      167   847.2484      230  1051.9782
42    472.7325    105    655.1663      168   849.3214      231  1055.3909
43    475.9141    106    659.8316      169   852.6053      232  1059.2382
44    479.0778    107    661.3675      170   856.0376      233  1063.5007
45    480.9206    108    664.0426      171   859.6738      234  1066.2681
46    483.5598    109    667.6396      172   863.4929      235  1068.9670
47    487.3832    110    670.2188      173   865.7373      236  1073.9716
48    489.9419    111    673.0377      174   868.4055      237  1075.6882
49    492.1505    112    677.4711      175   872.3803      238  1079.6127
50    495.6179    113    679.6326      176   875.2328      239  1083.1027
51    497.7992    114    682.0668      177   879.0570      240  1086.6284
52    500.9829    115    686.0143      178   881.4289      241  1089.3537
53    504.4008    116    688.6492      179   885.2314      242  1092.7966
54    506.7443    117    691.6828      180   888.7613      243  1096.3125
55    509.7821    118    694.6542      181   892.0937      244  1099.3362
56    512.6732    119    698.4924      182   895.2754      245  1104.0854
57    514.8358    120    700.9617      183   897.2797      246  1106.1711
58    518.5168    121    703.7869      184   901.5139      247  1109.6832
59    520.9057    122    706.4359      185   903.9839      248  1113.4952
60    524.6469    123    709.6463      186   907.1931      249  1117.2942
61    526.8958    124    712.4398      187   910.2802      250  1120.0276
62    529.1754    125    716.6992      188   913.4571      251  1123.8413
63    532.3863    126    719.1289      189   916.9567      252  1127.0125

5. Data Acquisition Methods

Measurements were made on aspen and hazelnut leaves obtained from the upper and 
lower canopy layers of the tree overstories.  At the sites, branches were 
accessed from canopy access towers erected by BOREAS Staff.  Stray light was 
measured at the beginning of each day and/or with each light source used. The 
color of the leaves was coded using the Munsell color chips (Munsell, 1977) 
prior to optical measurements. The method of sample measurement is described 
below:

The sample element filled the integrating sphere sample port.  Procedures for 
optical property measurements are described by Daughtry et al. (1989). 
Individual leaves or stems were cut from the plant.  The needles remained 
attached to the stem during the measurement.  Each leaf or needles measured was 
inserted into the integrating sphere sample port with the adaxial (top) surface 
facing the inside of the sphere.  Three measurements followed: 1) light 
reflected from the reference for the adaxial surface, 2) light reflected from 
the adaxial surface, and 3) light transmitted through the abaxial (bottom) 
surface. The sample was removed from the sample port and reinserted so that the 
abaxial surface faced the inside of the sphere; the sample was arranged so that 
the same portion of the sample was measured.  Three additional measurements 
followed: 1) light transmitted through the adaxial surface, 2) light reflected 
from the abaxial surface, and 3) light reflected from the reference for the 
abaxial surface.  All samples were illuminated with the standard external light 
source. Because of the difficulty in measuring needle samples, some 
transmittance values in the visible spectrum were calculated to be negative and 
were not indicative of true values.  The methodology used for correcting the 
transmittance values is given in Section 9.1.1.  For further information and 
indepth explanation regarding transmittance correction technique, please refer 
to Middleton et al. (IGARSS 1996).

6. Observations

6.1 Data Notes

None given.

6.2 Field Notes

None given.

7. Data Description

7.1 Spatial Characteristics

7.1.1 Spatial Coverage

Samples were taken from the top, middle and bottom of the canopy as indicated in 
the CANOPY_LOCATION parameter in the data sets.  The OJP, OA, and OBS samples 
were obtained with the aid of canopy access towers located at the OJP, OA, OA-
AUX, and OBS sites. The SSA measurement sites and associated North American 
Datum of 1983 (NAD83) coordinates are:

OBS canopy access tower located at the flux tower site, site id G8I4T, Lat/Long: 
53.98717 N, 105.11779 W, Universal Transverse Mercator (UTM) Zone 13, 
N:5,982,100.5 E;492,276.5.

OA canopy access tower located 100 m up the path to the flux tower site, site id 
C3B7T, Lat/Long: 53.62889 N, 106.19779 W, UTM Zone 13, N:5,942,899.9 
E:420,790.5.

OA-AUX was the canopy access tower located by the trailhead/parking area for the 
path leading to the flux tower at site id C3B7T, Lat/Long: 53.62889 N, 106.19779 
W, UTM Zone 13, N:5,942,899.9 E:420,790.5.  This SSA-OA-AUX site was farther up 
the path than SSA-OA from the flux tower site.

OJP canopy access tower flux tower site, site id G2L3T, Lat/Long: 53.91634 N, 
104.69203 W, UTM Zone 13, N:5,974,257.5 E:520,227.7.

YA canopy access tower, site id D0H4T, Lat/Long:  53.65601 N, 105.32314 W, UTM 
Zone 13, N:5,945,298.9, E:478,644.1.

YJP near flux tower site, site id F8L6T, Lat/Long: 53.87581 N, 104.64529 W, UTM 
Zone 13, N:5,969,762.5 E:523,320.2.

YA-AUX site id D6H4A, Lat/Long: 53.708 N, 105.315 W, UTM Zone 13, N: 5,951,112.1  
E: 479,177.5 near the Snow Castle Lodge.

Please note that at YA-AUX black spruce, jack pine, aspen, balsam fir, balsam 
poplar, tamarack, hazelnut, and several other shrub and herbaceous species were 
also present. 

7.1.2 Spatial Coverage Map

Not available.

7.1.3 Spatial Resolution

The measurements were obtained from single leaves and needles collected from 
sample trees near the coordinates given in Section 7.1.1.

7.1.4 Projection

Not applicable.

7.1.5 Grid Description

Not applicable.

7.2 Temporal Characteristics

Preparation for measurement took 5 minutes per broadleaf sample and 10 minutes 
per conifer sample.  The measurements for each sample took under 5 minutes.  
Samples were stored for 2 to 3 hours in the refrigerator.

7.2.1 Temporal Coverage

In 1994, data were collected from 24-May to 15-Sep.  In 1996, data were 
collected from 11 to 16-Jul.


7.2.2 Temporal Coverage Map

Samples were collected from 8:00 a.m. to 3:00 p.m. on the following days in 
1994:

Site               IFC-1                IFC-2                 IFC-3
--------        -----------          -----------           -----------
SSA-OBS         02-Jun-1994          29-Jul-1994           15-Sep-1994
SSA-OJP         01-Jun-1994          23-Jul-1994           08-Sep-1994
SSA-YJP         28-May-1994          23-Jul-1994           09-Sep-1994
SSA-YA-AUX      N/A                  31-Jul-1994           12-Sep-1994
SSA-OA          24-May-1994          20-Jul-1994           14-Sep-1994
                29-May-1994
                09-Jun-1994
SSA-YA          25-May-1994          29-Jul-1994           01-Sep-1994
                03-Jun-1994                                11-Sep-1994
SSA-OA-AUX      N/A                  20-Jul-1994           01-Sep-1994

For 1996:

Samples were collected from 8:00 a.m. to 3:00 p.m. on the following days in 
1996:

            Site             Dates        
          -------        -----------
          SSA-OBS        15-Jul-1996     
          SSA-OJP        12-Jul-1996     
          SSA-YJP        13-Jul-1996 and 16 Jul-1996 
          SSA-YA-AUX     11-Jul-1996     

7.2.3 Temporal Resolution

None given.

7.3 Data Characteristics                                                        

Data characteristics are defined in the companion data definition file 
(te10lopt.def).                                                                             


7.4 Sample Data Record                                                          
                                                                                
Sample data format shown in the companion data definition file (te10lopt.def).

8. Data Organization

8.1 Data Granularity

All of the TE-10 Leaf Optical Properties for SSA Species are contained in one 
dataset.

8.2 Data Format(s)

The data files contain a series of numerical and character fields of varying 
length separated by commas.  The character fields are enclosed in single 
quotation marks. There are no spaces between the fields. Sample data records are 
shown in the companion data definition file (te10lopt.def).

9. Data Manipulations

9.1 Formulae

In the formulas below, for leaf samples, the leaf would cover the whole area of 
the aperture resulting in a zero gap fraction and negating that term in the 
equation.

For 1994, these formulae were used for both conifers and broadleafs:

	          (Fr-Fn)   Rr
reflectance   = ------- * ---                                            [1]
	          (Fwr-Fn)  G3

			Ft      Rr
transmittance = ------- * ---                                            [2]
		    (Fwt-Fn)  G3
where
Fr = flux measured in reflectance mode
Ft = flux measured in transmittance mode
Fn = flux measured in reflectance mode with no sample
Fwr, Fwt = flux measured in reference mode for side of leaf illuminated during 
reflectance and transmittance measurements, respectively
Rr = reflectance of BaSO4 reference surface
G3 = function of sphere reflectance and geometry and
	sample reflectance


For 1996, these formulae were used for both conifers and broadleafs:

REFLECTANCE

                      (RT-STR)     1
Adaxial:     RC(top)=[---------]*------*100                             [3]
                      (RFT-STR)  (1-GF)



                        (RB-STR)    1
Abaxial:     RC(bottom)=[--------]*------*100                           [4]
                        (RFB-STR) (1-GF)


TRANSMITTANCE

                         TT           w*GF      1                       [5]
Adaxial:     TC(top)=[---------  -  -------]*------*100     (Old Formula)
                     (RFB-STR)     (X-STR)  (1-GF) 


                        TT           w*GF   2                           [6]
             TC(top)={---------  - [-------]  }*100         (Revised Formula)
                     (RFB-STR)     (X-STR)   

                        TT           w*GF   2    1                      [7]
             TC(top)={---------  - [-------]  }*------*100  (Revised Formula-2)
                     (RFB-STR)     (X-STR)  (1-GF) 

                            TB           w*GF      1                    [8]
Abaxial:     TC(bottom)=[---------  -  -------]*------*100     (Old Formula)
                         (RFT-STR)     (X-STR)  (1-GF) 


                            TB           w*GF   2                       [9]
             TC(bottom)={---------  - [-------]  }*100       (Revised Formula)
                         (RFT-STR)     (X-STR)   

                            TB           w*GF   2    1                  [10]
             TC(bottom)={---------  - [-------]  }*------*100(Revised Formula-2)
                         (RFT-STR)     (X-STR)     (1-GF) 

Parameters:
GF  gap fraction
RC  corrected reflectance
RFB observed reference standard bottom (adaxial)
RFT observed reference standard top (abaxial)
RB  observed reflectance bottom (side of needle surface)
RT  observed reflectance top (side of needle surface)
STR observed stray light in reflectance mode
TC  corrected transmittance
TB  observed transmittance bottom (side of needle surface) 
TT  observed transmittance top (side of needle surface)
w   observed sphere wall reflectance

9.1.1 Derivation Techniques and Algorithms

The corrected transmittance is a function of three parameters: the original 
calculated transmittance, gap fraction, and slope.

CALIBRATION DATA SET
In order to obtain values for the slope parameter, calibration data sets of 
conifer needles were taken in 1994 and 1996 at the sites in the SSA, located in 
the general vicinities of Candle Lake and Nipowan, Saskatchewan, Canada.  
Optical properties of the needles were then measured with varying gap fractions. 
Calibration data sets were compiled using gap fractions varying from 
approximately 0%-45%. The spectral regions associated with the greatest 
absorption (e.g., chlorophyll) were found to be most affected: negative 
transmittances were calculated in the visible for virtually all gap fractions, 
for these needles.

GAP FRACTION
Unlike broadleaves, conifer needles are unable to occupy the entire aperture of 
the measuring device.  Therefore, a certain percentage of energy is allowed to 
pass beyond the sample to the measuring device, without being disturbed by the 
physical properties of the needle.  This percentage is the gap fraction 
parameter, which is the percentage of aperture uncovered by needles.  Gap 
fraction was calculated for all the conifer needle samples.  Preliminary 
analysis suggested that the effect of the gap fraction on leaf optical 
properties was a function of energy wavelength.  In other words, gap fraction 
affected properties at higher percentages in the visible spectrum than in the 
near-infrared spectrum, implying the need for another parameter.

SLOPE for 1994
In order to obtain values for the slope parameter, a calibration data set of 
conifer needles was taken at sites in the SSA.  Optical properties of the 
needles were then measured with varying gap fractions and similar techniques as 
used for the three IFCs. The spectral regions associated with the greatest 
absorption (e.g., chlorophyll) were found to be most affected: negative 
transmittance were calculated in the visible for virtually all gap fractions, 
for these needles.  The measured transmittance is linearly related to gap 
fraction, and the regression coefficients of these relationships was used as the 
slope parameter.

SLOPE for 1996
Slope is calculated by using the transmittance data from the calibration data 
sets.  The measured transmittance is linearly related to gap fraction, and the 
regression coefficients of these relationships was used as the slope parameter.  
It was deemed unnecessary to use any correction below a 17% gap fraction.

CORRECTED TRANSMITTANCE
The corrected transmittance values were then calculated as the product of gap 
fraction and slope, subtracted from the original calculated transmittance.

(Corrected T) = (Measured T) - (Gap Fraction * Slope)                   [11]     

9.2 Data Processing Sequence

9.2.1 Processing Steps

None given.

9.2.2 Processing Changes

None given.

9.3 Calculations

None given.

9.3.1 Special Corrections/Adjustments

Because different procedures were used in 1996 by the instrument operator, a 
correction was applied to the 1996 black spruce data to make them consistent 
with all the other data collected in 1994 and 1996.  During all but the 1996 
black spruce collection sessions, the integrating sphere was empty during 
referencing procedures. In 1996, an empty sample holder was in place on the 
integrating sphere at all times, including when the initial reference 
measurements were made. 

Having the empty sample holder in place during the initial referencing 
procedures in the 1996 black spruce sessions resulted in a reduction of black 
spruce reflectance values.  This affected the black spruce data due to the very 
small needle size which necessitated the use of the sample holder with the 
slitted aperture.  To normalize the 1996 black spruce data with the other data 
collected in 1994 and 1996, an offset value was calculated by using a ratio of 
stray light from the wall (STRW) to the stray light from the sample (STRS), 
which was then applied to the data.  The offset value for black spruce was 
calculated by:
                                                                        [12]
(STRW/STRS ratio of 1996 jack pine data)/(STRW/STRS ratio of 1996 black spruce 
data) = offset for the 1996 black spruce data.

9.3.2 Calculated Variables

None given.

9.4 Graphs and Plots

None given.

10. Errors

10.1 Sources of Error

During the 1996 summer collection session, a slightly different data acquisition 
methodology was used which resulted in a reduction of black spruce reflectance 
values.  An empty sample holder was in place within the integrating sphere at 
all times, including during the initial reference-taking steps.  Previously, the 
sample holder was absent while referencing.  This affected only the black spruce 
data because of the very small needle size, which necessitated the use of the 
sample holder with the slitted aperture.  To normalize the 1996 summer session 
black spruce data with the other data from 1994 and 1996, an offset value was 
calculated by using a ratio of the STRW/STRS from the 1996 black spruce data and 
the STRW/STRS from the 1996 jack pine data, which was then applied to the data.  
The offset was calculated using:

(STRW/STRS ratio of 1996 jack pine data)/(STRW/STRS ratio of 1996 black spruce 
data) = offset for the 1996 black spruce data.

10.2 Quality Assessment

10.2.1 Data Validation by Source

Comparisons were made with other BOREAS results and with published results.

10.2.2 Confidence Level/Accuracy Judgment

In 1994, the methods used during IFC-1 produced some minor distortions in the 
data that were not totally eliminated by postcollection processing, resulting in 
an 80% confidence level in IFC-1 data.  Revisions in techniques and streamlining 
of sample collection and measurement methods were implemented as needed.  These 
occurred mainly during IFC-1, which acted as TE-10's learning phase. Therefore, 
confidence in IFC-2 and IFC-3 data is much stronger, with a degree of 
reliability greater than 90%.

10.2.3 Measurement Error for Parameters

None given.

10.2.4 Additional Quality Assessments

Calculated results were plotted, and the plots were compared with those from 
published papers.

10.2.5 Data Verification by Data Center

Data were examined for general consistency and clarity.

11. Notes

None given.

11.1 Limitations of the Data

None given.

11.2 Known Problems with the Data

Because of the difficulty in measuring needle samples, some transmittance values 
in the visible spectrum measured negative and were not indicative of true 
values.

11.3 Usage Guidance

None given.

11.4 Other Relevant Information

In 1996, the small size and quantity of black spruce needles present on the 
trees sampled, because of low production, necessitated combining two age classes 
of needles in several instances to achieve a large enough sample size.

Acknowledgment of other research staff who assisted in this study:
Scott K. Mitchell, UMD Undergraduate Student
Robert J. Rusin, UMD Undergraduate Student
David A. Shirey, UMD Graduate Student

12. Application of the Data Set

This data set will be of interest to investigators undertaking data comparisons 
and integrations, and parameterization or validation of canopy models requiring 
leaf-level optical information at these and similar sites.

13. Future Modifications and Plans

None given.

14. Software

14.1 Software Description

Computer Eyes /RT (Digital Vision, Inc., Dedham, MA)
Custom software developed by M.A. Mesarch of UNL
Excel 5.0 for Windows (Microsoft)
Mocha (SPSS, Inc., Chicago, IL)
Systat 6.0 (SPSS, Inc., Chicago, IL)

14.2 Software Access

None given.

15.   Data Access

15.1  Contact for Data Center/Data Access Information

These BOREAS data are available from the Earth Observing System Data and 
Information System (EOS-DIS) Oak Ridge National Laboratory (ORNL) Distributed 
Active Archive Center (DAAC). The BOREAS contact at ORNL is:

ORNL DAAC User Services
Oak Ridge National Laboratory
(865) 241-3952
ornldaac@ornl.gov
ornl@eos.nasa.gov

15.2  Procedures for Obtaining Data

BOREAS data may be obtained through the ORNL DAAC World Wide Web site at 
http://www-eosdis.ornl.gov/ or users may place requests for data by telephone, electronic mail, or fax.

15.3  Output Products and Availability

Requested data can be provided electronically on the ORNL DAAC's anonymous FTP 
site or on various media including, CD-ROMs, 8-MM tapes, or diskettes.

The complete set of BOREAS data CD-ROMs, entitled "Collected Data of the Boreal 
Ecosystem-Atmosphere Study", edited by Newcomer, J., et al., NASA, 1999, are 
also available.

16. Output Products and Availability

16.1 Tape Products

None

16.2 Film Products

None.

16.3 Other Products

Tabular American Standard Code for Information Interchange (ASCII) files.

17. References

17.1 Platform/Sensor/Instrument/Data Processing Documentation

LI-COR LI-1800-12 Integrating Sphere Instruction Manual. 1983. Pub. No.  8305-
0034. LI-COR, Inc., Lincoln, NE.

Spectron Engineering, Inc., Operating Manual: SE590 field portable data-logging
spectroradiometer, Serial Number Spectron Engineering, Denver, CO  80223.

17.2 Journal Articles and Study Reports

Daughtry, C.S.T., L.L. Biehl, and K.J. Ranson. 1989.  A new technique to measure 
the spectral properties of conifer needles.  Remote Sensing Environment 27:81-
91.

Esau, K. 1977. Anatomy of Seed Plants, 2nd ed. John Wiley & Sons, New York, 550 
pp.

Mesarch, M.A. et al. 1998. A Revised Measurement Methodology for Conifer Needles 
Spectral Properties:  Evaluating the Influence of Gaps Between Elements.  Remote 
Sensing Review.  (submitted 1998).

Middleton, E.M. et al. 1996. A Revised Measurement Methodology for Spectral 
Optical Properties of Conifer Needles.  As presented for Proceedings, 1996 
International Geoscience and Remote Sensing Symposium (IGARSS '96). 

Middleton, E.M., S.S. Chan, R.J. Rusin and S.K. Mitchell. 1997. Optical 
Properties of Black Spruce and Jack Pine needles at BOREAS sites in 
Saskatchewan, Canada.  Canadian Journal of Remote Sensing. vol. 23, no. 2, pp. 
108-119.  

Munsell Color (Firm). 1977.  Munsell Color Charts for Plants Tissues.  2nd ed. 
Munsell Color (Firm), Baltimore, MD, 6 pp. 17 color charts.

Norman, J.M. and P.G. Jarvis. 1974.  Photosynthesis in Stika Spruce [Picea 
Sitchenis (Bong.) Carr.] III. Measurements of canopy structure and interception 
of radiation. J. Appl. Ecol. 11:375-398.

Sellers, P. and  F. Hall. 1994. Boreal Ecosystem-Atmosphere Study: Experiment 
Plan. Version 1994-3.0, NASA BOREAS Report (EXPLAN 94).

Sellers, P., F. Hall, H. Margolis, B. Kelly, D. Baldocchi, G. den Hartog, J. 
Cihlar, M.G. Ryan, B. Goodison, P. Crill, K.J. Ranson, D. Lettenmaier, and D.E. 
Wickland. 1995. The boreal ecosystem-atmosphere study (BOREAS): an overview and 
early results from the 1994 field year. Bulletin of the American Meteorological 
Society. 76(9):1549-1577.

Sellers, P., F. Hall, and K.F. Huemmrich. 1996. Boreal Ecosystem-Atmosphere 
Study: 1994 Operations. NASA BOREAS Report (OPS DOC 94).

Sellers, P.  and F. Hall. 1996. Boreal Ecosystem-Atmosphere Study: Experiment 
Plan. Version 1996-2.0, NASA BOREAS Report (EXPLAN 96).

Sellers, P., F. Hall, and K.F. Huemmrich. 1997. Boreal Ecosystem-Atmosphere 
Study: 1996 Operations. NASA BOREAS Report (OPS DOC 96).

Sellers, P.J., F.G.  Hall, R.D.  Kelly, A. Black, D. Baldocchi, J. Berry, M.  
Ryan, K.J.  Ranson, P.M.  Crill, D.P.  Lettenmaier, H. Margolis, J. Cihlar, J. 
Newcomer, D. Fitzjarrald, P.G.  Jarvis, S.T. Gower, D. Halliwell, D. Williams, 
B. Goodison, D.E. Wickland, and F.E. Guertin. 1997. BOREAS in 1997: Experiment 
Overview, Scientific Results and Future Directions. Journal of Geophysical 
Research 102 (D24): 28,731-28,770.

Smith, W.K. and G.A. Carter. 1988.  Shoot structural effects on needle 
temperatures and photosynthesis in conifers.  Amer. J. of Bot. 75:496-500.

Wickland, D. 1995. The boreal ecosystem-atmosphere study (BOREAS): an overview 
and early results from the 1994 field year. Bulletin of the American 
Meteorological Society. 76(9):1549-1577.

Williams, D.L. 1991.  A comparison of spectral reflectance properties at the 
needle branch and canopy level for selected conifer species.  Remote Sensing 
Environment  35:79-93.

17.3 Archive/DBMS Usage Documentation

None.

18. Glossary of Terms

Abaxial:          The ventral or underside of leaf or needle.
Adaxial:          The dorsal or upper of leaf or needle.
Channel (ch):     One band on the SE590, each having a unique wavelength.
Gap fraction:     The percentage of aperture not covered by needles.
Reflectance (R):  Light shines on the specified surface, bounces off this 
                  surface, and then bounces around in the integrating sphere; 
                  the spectroradiometer then measures the integrated light that 
                  is bouncing around in the sphere.
STRS:             Stray light from the sample.
STRW:             Stray light from the wall.

Transmittance (T): Light shines on the specified surface, goes through the 
needle, and then passes into the integrating sphere; the spectroradiometer then 
measures the integrated light that is bouncing around in the sphere.


19. List of Acronyms

ASCII   - American Standard Code for Information Interchange
BOREAS  - BOReal Ecosystem-Atmosphere Study
BORIS   - BOREAS Information System
B/W     - Black and White 
CCD     - Charge-Coupled Device
DAAC    - Distributed Active Archive Center
EOS     - Earth Observing System
EOSDIS  - EOS Data and Information System
fAPAR   - fraction of Absorbed Photosynthetically Active Radiation
GF      - Gap Fraction
GMT     - Greenwich Mean Time
GSFC    - Goddard Space Flight Center
IFC     - Intensive Field Campaign
IGARSS  - International Geoscience And Remote Sensing Symposium
NAD83   - North American Datum of 1983
NASA    - National Aeronautics and Space Administration
NDVI    - Normalized Difference Vegetation Index
NSA     - Northern Study Area
OA      - Old Aspen
OA-AUX  - Old Aspen Auxiliary
OBS     - Old Black Spruce 
OJP     - Old Jack Pine
ORNL    - Oak Ridge National Laboratory
PANP    - Prince Albert National Park
PAR     - Photosynthetically Active Radiation
SSA     - Southern Study Area 
STDEV   - Standard Deviation
SVI     - Spectral Vegetation Index
TE      - Terrestrial Ecology
URL     - Uniform Resource Locator
UTM     - Universal Transverse Mercator
WS      - White Spruce
YA      - Young Aspen
YA-AUX  - Young Aspen Auxiliary
YJP     - Young Jack Pine

20. Document Information

20.1 Document Revision Date

Written:       26-Jun-1997
Last updated:  28-Sep-1998

20.2 Document Review Date(s)

BORIS Review:    15-Jul-1998
Science Review:  06-Aug-1998

20.3 Document ID

20.4 Citation

S.S. Chan and E M. Middleton
Biospheric Sciences Branch, Code 923
NASA GSFC

20.5 Document Curator

20.6 Document URL

Keywords
Optical Properties
Spectra
Reflectance
Transmittance

TE10_Leaf_Optic.doc
10/09/98