BOREAS RSS-14 Level-2 GOES-7 Shortwave and Longwave Radiation Images

Summary

The BOREAS RSS-14 team collected and processed several GOES-7 and GOES-8
image data sets that covered the BOREAS study region. This data set
contains images of shortwave and longwave radiation at the surface and
top of the atmosphere derived from collected GOES-7 data. The data cover
the time period of 05-Feb-1994 to 20-Sep-1994. The images missing from
the temporal series were zero-filled to create a consistent sequence of
files. The data are stored in binary image format files.

Note that the level-2 GOES-7 data are not contained on the BOREAS CD-ROM
set. An inventory listing file is supplied on the CD-ROM to inform users
of the data that were collected. See Sections 15 and 16 for information
about how to acquire the data.

Table of Contents

1\) Data Set 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

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 RSS-14 Level-2 GOES-7 Shortwave and Longwave Radiation Images

1.2 Data Set Introduction

For the BOReal Ecosystem-Atmosphere Study (BOREAS), the level-2
Geostationary Operational Environmental Satellite 7 (GOES-7) imagery,
along with the other remotely sensed images, were collected in order to
provide spatially extensive information over the primary study areas at
varying spatial scales. These level-2 GOES-7 shortwave and longwave
(SW/LW) images acquired and processed by Dr. Eric Smith serve to define
the surface radiation budget (SRB) for the BOREAS region.

1.3 Objective/Purpose

The primary objectives are 1) to retrieve the SRB from the level-1
GOES-7 visible images over the BOREAS region at a high temporal and
spatial resolution, and 2) to quantify the uncertainties of
satellite-derived SRB products.

1.4 Summary of Parameters

The level-2 GOES-7 SW/LW product contains the following parameters:

\*Narrow-band albedo at TOA (0.5 to 0.7 µm) \[0.1 %\]

Column water vapor amount \[0.01 cm\]

\*SW down at TOA (0.3 to 3.0 µm) \[0.1 W/m^2^\]

\*Narrow-band albedo at TOA (0.5 to 0.7 µm) \[0.1 %\]

Narrow-band cloud albedo (0.5 to 0.7 µm) \[0.1 %\]

Narrow-band minimum albedo (0.5 to 0.7 µm) \[0.1 %\]

SW down at surface (0.3 to 3.0 µm) \[0.1 W/m^2^\]

SW up at surface (0.3 to 3.0 µm) \[0.1 W/m^2^\]

Surface SW albedo (0.3 to 3.0 µm) \[0.1 %\]

\*PAR down (0.4 to 0.7 µm) \[0.1 W/m^2^\]

\*PAR up (0.4 to 0.7 µm) \[0.1 W/m^2^\]

\*PAR albedo (0.4 to 0.7 µm) \[0.1 %\]

Net LW at surface (4.0 to 100.0 µm) \[0.1 W/m^2^\]

\* where TOA is the top of the atmosphere, and PAR is photosynthetically
active radiation.

1.5 Discussion

Dr. Eric Smith, from Florida State University (FSU), provided the BOREAS
Information System (BORIS) with the level-1 GOES-7 images that were used
to create the level-2 products.

1.6 Related Data Sets

BOREAS RSS-14 Level-1 GOES-7 Visible, Infrared, and Water-Vapor Images

BOREAS RSS-14 Level-3 Gridded Radiometer and Satellite Surface Radiation
Images

BOREAS RSS-14 Level-1 GOES-8 Visible, Infrared, and Water-Vapor Images

BOREAS RSS-14 Level-1a GOES-8 Visible, Infrared, and Water-Vapor Images

2\. Investigator(s)

2.1 Investigator(s) Name and Title

Dr. Eric A. Smith, Professor

2.2 Title of Investigation

Surface Radiation Budget Retrieved from GOES-7 VISSR Imagery for Large
Scale BOREAS Area

2.3 Contact Information

Contact 1

\-\-\-\-\-\-\-\--

Ms. Jiujing Gu

Florida State University

Tallahassee, FL

\(904\) 644-7511

\(904\) 644-9639 (fax)

jgu@huey.met.fsu.edu

Contact 2

\-\-\-\-\-\-\-\--

Dr. Eric A. Smith

Florida State University

Tallahassee, FL

\(904\) 644-4253

\(904\) 644-9639 (fax)

esmith@metsat.met.fsu.edu

Contact 3

\-\-\-\-\-\-\-\--

Jaime Nickeson

Raytheon ITSS

NASA GSFC

Greenbelt, MD

\(301\) 286-7858

\(301\) 286-0239 (fax)

Jaime.Nickeson@gsfc.nasa.gov

3\. Theory of Measurements

The GOES mission is to provide the nearly continuous, repetitive
observations that are needed to predict, detect, and track severe
weather. GOES spacecraft are equipped to observe and measure cloud
cover, surface conditions, snow and ice cover, surface temperatures, and
the vertical distributions of atmospheric temperature and humidity. They
are also instrumented to measure solar X-rays and other energetics,
collect and relay environmental data from platforms, and broadcast
instrument data and environmental information products to ground
stations. The GOES system includes the satellite (with the GOES
instrumentation and direct downlink data transmission capability); the
National Environmental Satellite, Data and Information Service (NESDIS)
facility at Wallops Island, VA; and the ground systems at NESDIS.

4\. Equipment

4.1 Sensor/Instrument Description

The original GOES instrument was the Visible and Infrared Spin Scan
Radiometer (VISSR), which was an outgrowth of the spin-scan radiometer
flown aboard several of the Applications Technology Satellite (ATS)
series of National Aeronautics and Space Administration (NASA) research
satellites. The VISSR was first flown aboard Synchronous Meteorological
Satellites (SMS)-1 and -2 used by the National Oceanic and Atmospheric
Administration (NOAA). GOES-1, -2, and -3 were operational satellites
that flew the original VISSR instrument. GOES-4 through -7 were flown
with a modified instrument package called the VISSR Atmospheric Sounder
(VAS). A set of infrared sensors was added to provide an atmospheric
sounder capability.

The VAS instrument system is an expansion of the VISSR system with
improved structural design and some additional capabilities. It consists
of the same type of scanning system, a telescope with lighter weight
optics made from beryllium instead of conventional materials (glass,
steel), eight visible detectors (25 x 24 microradian Instantaneous Field
of View (IFOV)), and six infrared detectors.

4.1.1 Collection Environment

The data were acquired using the FSU Direct Readout Ground System
located in Tallahassee, FL, starting on 01-Jan-1994 and continuing
through July 1995. The GOES-7 satellite orbited Earth in a geostationary
orbit at an altitude of 42,000 km.

4.1.2 Source/Platform

Launch and data-available dates for the GOES-7 satellite are:

Satellite Launch Date Data Range

\-\-\-\-\-\-\-\-- \-\-\-\-\-\-\-\-\-\--
\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

GOES-7 26-Feb-1987 25-Mar-1987 to mid-1995

4.1.3 Source/Platform Mission Objectives

See Sections 1.3 and 3.

4.1.4 Key Variables

The key variables in this data set are:

\-- surface downward solar and PAR flux

\-- surface broad-band and narrow-band albedo

\-- surface net LW flux

4.1.5 Principles of Operation

The VISSR instrument consists of a scanning system, telescope, and
infrared and visible sensors. The scanning system consists of a mirror
that is stepped mechanically to provide north to south viewing, while
the 100-rpm rotation of the GOES satellite provides west to east
scanning. The mirror is stepped following each west to east scan. The
mirror position is controlled by one of two optical encode wheels
attached to the axis. Each step of the mirror causes a change of 192
µrad in the scan angle, representing a distance of 6.9 km near nadir. A
sequence of 1,821 scans over 18.21 minutes is performed to provide a
\"full disk\" view from just beyond the northern Earth horizon to just
beyond the southern Earth horizon.

The scanning mirror reflects the received radiation into a
16-inch-diameter telescope. A fiber-optics bundle is used to couple the
telescope to eight visible detectors (sensitive to the 0.54 to 0.70
micrometer band). The fiber optics bundle is configured such that each
of the eight visible sensors has a 20 (W-E) by 25 (N-S) microradian
(µrad) FOV on GOES-7. The sensors are arranged in a linear array
oriented \"north-south\" (i.e., perpendicular to the scan direction)
thus sweeping out eight parallel scan line paths as the satellite
rotates. The FOV provides a ground resolution of 0.9 km (normally
referred to as 1 km or 0.5 nautical miles). The system thus provides
eight parallel 1 visible data lines per west to east scan, covering the
6.9-km (normally referred to as 8-km or 4-mile) band scanned by each
step of the scanning mirror. In addition, germanium relay lenses are
used to pass received radiation to two HgCdTe infrared detectors by way
of a 10.5 to 12.6 micrometer bandpass filter. The FOV of the infrared
detectors is 192 µrad (equal to the north-south scan step angle), and
thus the infrared sensors provide equivalent coverage to the eight
visible sensors.

The output from the eight visible detectors and from one of the two
infrared detectors (or an average of both infrared detectors) is
digitized onboard the satellite and transmitted down to Earth in real
time. The visible data are sampled every 2 microseconds, which yields
visible samples spaced at increments of satellite rotation of 20.9 µrad
(assuming a nominal satellite spin rate of 100 rpm), or a near-nadir
spacing of 3.0 km. Since the infrared detector FOV is 192 microradians,
the infrared data are therefore oversampled in the scan direction. The
quantization of the infrared data is 8 bits, and of the visible data 6
bits. The visible scanners are digitized with a square root digitizer
for better signal-to-noise ratio. The oversampling of the infrared data
leads to their designation as \"4 by 2\" infrared data (4-mile
resolution north-south, 2-mile resolution west-east). The
full-resolution scan of all sensors in the mode produces about 226
Mbytes of data per image.

4.1.6 Sensor/Instrument Measurement Geometry

When the VISSR/VAS is installed in the spacecraft, its optical axis
becomes parallel to the spacecraft spin axis, which must be parallel to
Earth\'s spin axis. The VAS optical axis is thus perpendicular to the
direction of the Earth scene. The optically flat scan mirror of the VAS,
placed at a 45-degree angle to the VAS optical axis, directs the Earth
scene into the VAS. The spinning is accomplished by stepping the scan
mirror from 40 degrees, representing the north polar extreme, to 50
degrees, representing the south polar extreme. An angle position encoder
integral with the mirror stepping mechanism converts the position
information to electrical signals, which are sent to the Command and
Data Acquisition (CDA) station to aid in reassembly of the Earth scene.
The 10 degrees of mirror motion (resulting in 20 degrees of optical
angle after doubling the optical angle at the mirror) is divided into
1,821 steps, each representing 192 µrad optically.

At the image plane, a relatively large FOV is available. Each detector
element is dimensional to define the FOV its signal is intended to
represent. For example, the smallest infrared field is 192 µrad defined
by a square detector 0.00315 inches on each side. (At synchronous
altitude, 192 µrad is equivalent to 5 miles along Earth\'s surface at
the satellite\'s suborbital point.)

Two focal planes are used in the VAS. Visible spectrum signals are
obtained at the principal focus. An optical fiber for each of the eight
FOVs defines the field to be measured (25 by 24 microradian) and conveys
the impinging light within that FOV to a photomultiplier tube (PMT),
which converts the light intensity to a proportional electrical current.
Infrared radiation must be sensed by solid state detectors, which are
cooled to a low temperature to reduce their intrinsic electrical noise
to a level below the electrical equivalent of the least intense
radiation to be measured. This cooling is provided by a radiation cooler
that radiates excess heat into space. Because of spacecraft design
constraints, the cooler must be located away from the prime focal plane.
The relay optics provide an appropriate location for an infrared
focusing mechanism and filter assembly out of the visible light path.
The filter assembly contains a 11.2-centimeter disc, called a filter
wheel, that houses 12 spectral pass band filters. During each scan, one
filter is placed in the infrared path to acquire data in the desired
spectral band. Any one of the filters can be positioned in the infrared
optical FOV within 350 milliseconds (i.e., during the time that the VAS
telescope is not viewing Earth during a given spin). Filters are
inserted in the infrared path only and used in the Multispectral Imaging
(MSI) and sounding modes. While 38 channels are possible with the filter
wheel detector combinations, only 13 bands can be transmitted.

The scanning schedule and the various modes of operation are uploaded to
an electronics module in the satellite. The satellite includes an
onboard controller that can itself be reprogrammed via the spacecraft
command link.

4.1.7 Manufacturer of Sensor/Instrument

Hughes Santa Barbara Remote Sensing (SBRS)

Goleta, CA

4.2 Calibration

The visible channels are calibrated in a vacuum environment at five
instrument temperature plateaus. Some adjustments are made to
standardize the bit content and start time of the stretched data scans.

Preflight Calibration

a\. Visible Channel Calibration: The visible channel calibration source
is a quartz iodine lamp, the output of which is collimated and
spectrally shaped using appropriate optical filters similar to the sun
over the spectral band of the visible channels. The output level of the
calibration source is established by eight neutral density filters that
provide a calibration range from 16% to 100% albedo. The absolute
calibration accuracy of the visible channels is estimated to be +/- 10%.

b\. Thermal Channel Calibration: The visible thermal channels are
calibrated at eight target scene temperatures between 180 and 315 K,
using a temperature-controlled blackbody source. The estimated absolute
calibration accuracy is +/- 1.5 °C, or +/- 1% of full scale, whichever
is larger.

In-flight Calibration

a\. Visible Channels: In-flight calibration of the eight visible PMTs is
accomplished by viewing the sun through the complete visible channel
optical train via a \"side-looking,\" reduced-aperture collecting prism.
The visible channel gains are adjusted in the ground station processing
to equalize the eight scanners. This is done to remove stripping of the
images. Other gain adjustments are occasionally made for image clarity.
Absolute calibrations with the sun viewer are not part of the GOES
operating procedure. However, some research programs have produced
limited calibrations for parts of the GOES data record.

b\. Thermal Channel: The in-flight calibration of the visible thermal
channel is accomplished by monitoring the temperature of a black-body.
This blackbody is activated by command and introduced into the optical
path just ahead of the infrared relay optical system. The space view by
visible provides an approximately zero signal reference in the thermal
bands that is used to establish the zero-end of the measurement scale.

4.2.1 Specifications

IFOV

Visible 25 x 24 microradians

Infrared 192 x 192 microradians

RESOLUTION (subsatellite)

Visible 0.9 km

Infrared 6.9 km

ALTITUDE 35,600 km

GOES SPIN RATE 100 rpm

SCAN RATE 1821 scans/min

SCAN RANGE approx. 60°N to 60°S

SAMPLES/SCAN 3,822 infrared and 15,288 visible samples per PMT

detector per Earth scan

ORBIT POSITION: 0.0°N, 75.0°W

4.2.1.1 Tolerance

None given.

4.2.2 Frequency of Calibration

Calibration of the visible and infrared channels is performed after
every scan using internal calibrators that are part of the VAS VISSR
instrumentation. However, routine calibrations are not made on the
visible sensor.

4.2.3 Other Calibration Information

It has been reported by Rossow et al. (1995) that the sensitivities of
the VISSR instruments deteriorate at a rate of about 10% per year, and
with some short-term variabilities. To account for these sensitivity
changes, we have applied the calibration coefficients from International
Satellite Cloud Climatology Project (ISCCP) to the GOES-7 visible
imagery to convert visible counts to TOA radiances. The ISCCP
calibration is available for every month during most of the 1994
Intensive Field Campaigns (IFCs) and Field Focused Campaigns (FFCs).
Further information about ISCCP calibration can be found at
http://isccp.giss.nasa.gov/calib.html.

5\. Data Acquisition Methods

The BOREAS level-2 SW/LW images were created from level-1 GOES-7 visible
images. The imagery was obtained by Dr. Eric Smith at FSU and supplied
to BORIS. The data were acquired using the FSU Direct Readout Ground
System located in Tallahassee, FL, starting on 01-Jan-1994 and
continuing through December 1995.

6\. Observations

6.1 Data Notes

None given.

6.2 Field Notes

Not applicable.

7\. Data Description

7.1 Spatial Characteristics

7.1.1 Spatial Coverage

The scanning system consists of a mirror that is stepped mechanically to
provide north to south viewing, while the rotation of the GOES satellite
provides west to east scanning. The mirror is stepped following each
west to east scan. A sequence of 1,821 scans over 18.21 minutes is
performed to provide a \"full disk\" view from just beyond the northern
Earth horizon to just beyond the southern Earth horizon.

Based on the level-1 GOES-7 images, the level-2 SW/LW product covers the
entire 1,000-km by 1,000-km BOREAS region. This contains the Southern
Study Area (SSA), the Northern Study Area (NSA), the transect region
between the SSA and NSA, and some surrounding area.

Based on information contained in the reference latitude and longitude
files for the visible band (see Section 8.2), the following North
American Datum of 1983 (NAD83) coordinates represent the nominal
coverage of the level-2 SW/LW product:

Latitude Longitude

\-\-\-\-\-\-\-\-\-- \-\-\-\-\-\-\-\-\-\--

Northwest 64.757 N 107.037 W

Northeast 65.911 N 87.120 W

Southwest 47.646 N 109.210 W

Southeast 47.916 N 98.087 W

The NAD83 corner coordinates of the BOREAS region are:

Latitude Longitude

\-\-\-\-\-\-\-\-\-- \-\-\-\-\-\-\-\-\-\--

Northwest 59.97907 N 111.00000 W

Northeast 58.84379 N 93.50224 W

Southwest 51.00000 N 111.00000 W

Southeast 50.08913 N 96.96951 W

7.1.2 Spatial Coverage Map

Not available at this time.

7.1.3 Spatial Resolution

The GOES-7 SW/LW images have a nominal pixel resolution of 8 x 8 km
(approximately 14.2 x 6.6 km at BOREAS latitudes). For details, see
Kelly, 1989.

7.1.4 Projection

The BOREAS level-2 SW/LW data are stored in the same GOES \'perfect\'
projection as the level-1 images. The \'perfect\' projection indicates
that the satellite movement between temporal acquisitions has been
removed so the images are aligned spatially. Detailed information about
the projection is not currently available.

7.1.5 Grid Description

Not available at this revision.

7.2 Temporal Characteristics

7.2.1 Temporal Coverage

The SW images provide continuous coverage for the period of 05-Feb to
20-Sep-1994. The LW images cover only the snow-free period from 23-May
to 20-Sep-1994.

7.2.2 Temporal Coverage Map

The times when images were acquired varied over the year. The following
table gives the times when data are available:

Dates Times

\-\-\-\-\-\-\-\-\-\-\-\-\-\-- \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

05-Feb - 14-Feb 16:00 - 21:00 UTC

15-Feb - 14-Mar 15:30 - 22:00 UTC

14-Mar - 11-Apr 14:00 - 23:30 UTC

12-Apr - 02-May 13:00 - 00:30 UTC

03-May - 08-Aug 13:00 - 01:30 UTC

09-Aug - 28-Aug 13:00 - 00:30 UTC

29-Aug - 20-Sep 14:00 - 00:30 UTC

7.2.3 Temporal Resolution

The images were acquired every 30 minutes during the specified time
periods of each day.

7.3 Data Characteristics

Data characteristics are defined in the companion data definition file
(goes72.def).

7.4 Sample Data Record

Sample data format shown in the companion data definition file
(goes72.def).

8\. Data Organization

8.1 Data Granularity

The smallest unit of data for the level-2 GOES-7 SW/LW imagery is a
series of SW or LW images for a given day.

8.2 Data Format(s)

The data file contain numerical and character fields of varying length
separated by commas. The character fields are enclosed with single
apostrophe marks. There are no spaces between the fields. Sample data
records are shown in the companion data definition file (goes72.def).

A complete day of SW and LW data is contained in several SW files and
one LW file. The storage format/arrangement of the data is due to the
manner in which the SW and LW components were derived and delivered by
FSU.

Each SW file contains all the SW parameter images for one 30-minute
period. The SW file contains 49 records of 8192 bytes. Each SW parameter
image contains 128 2-byte pixel values in each of the 128 lines and is
stored in four data file records (i.e., 128 \* 2 \* 128 = 32,768 and
32,768/4 = 8,192). The series of records in the SW file is:

Record Number Content Storage format

\-\-\-\-\-\-\-\-\-\-\-\--
\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--
\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

01 Header Record (128 ASCII Characters/Line)

02-05 Scaled Visible Reflectance (16 bit integers)

06-09 Scaled Water Vapor (16 bit integers)

10-13 Scaled TOA Down (16 bit integers)

14-17 Scaled NB TOA Albedo (16 bit integers)

18-21 Scaled NB Cloud Albedo (16 bit integers)

22-25 Scaled NB Minimum Albedo (16 bit integers)

26-29 Scaled SW Down (16 bit integers)

30-33 Scaled SW Up (16 bit integers)

34-37 Scaled Surface Albedo (16 bit integers)

38-41 Scaled PAR Down (16 bit integers)

42-45 Scaled PAR Up (16 bit integers)

46-49 Scaled PAR Albedo (16 bit integers)

Each LW file contains all the LW parameter images delivered for a given
day. The LW files contain 105 records of 8,192 bytes each (105 \* 8,192
= 860,160 bytes per file), one record (8,192 bytes) for the header, and
four records for each of 26 images, equaling a total of 104 records of
image data. Each LW parameter image contains 128 2-byte pixel values in
each of the 128 lines, stored in four 8,192-byte records (128 samples \*
2 bytes \* 128 lines = 32,768 bytes, and 32,768/4 = 8192). The series of
records in the LW file are:

Record Number Content Storage format

\-\-\-\-\-\-\-\-\-\-\-\--
\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--
\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

01 Header Record (128 ASCII Characters/Line)

002-005 Image for 1300 UTC (16 bit integers)

006-009 Image for 1330 UTC (16 bit integers)

010-013 Image for 1400 UTC (16 bit integers)

014-017 Image for 1430 UTC (16 bit integers)

018-021 Image for 1500 UTC (16 bit integers)

022-025 Image for 1530 UTC (16 bit integers)

026-029 Image for 1600 UTC (16 bit integers)

030-033 Image for 1630 UTC (16 bit integers)

034-037 Image for 1700 UTC (16 bit integers)

038-041 Image for 1730 UTC (16 bit integers)

042-045 Image for 1800 UTC (16 bit integers)

046-049 Image for 1830 UTC (16 bit integers)

050-053 Image for 1900 UTC (16 bit integers)

054-057 Image for 1930 UTC (16 bit integers)

058-061 Image for 2000 UTC (16 bit integers)

062-065 Image for 2030 UTC (16 bit integers)

066-069 Image for 2100 UTC (16 bit integers)

070-073 Image for 2130 UTC (16 bit integers)

074-077 Image for 2200 UTC (16 bit integers)

078-081 Image for 2230 UTC (16 bit integers)

082-085 Image for 2300 UTC (16 bit integers)

086-089 Image for 2330 UTC (16 bit integers)

090-093 Image for 0000 UTC (next day) (16 bit integers)

094-097 Image for 0030 UTC (next day) (16 bit integers)

098-101 Image for 0100 UTC (next day) (16 bit integers)

102-105 Image for 0130 UTC (next day) (16 bit integers)

9\. Data Manipulations

9.1 Formulae

9.1.1 Derivation Techniques and Algorithms

The solar parameters were retrieved from GOES-7 visible images using a
physical retrieval algorithm described in Gu and Smith (1997). The
algorithm includes parameterization of Rayleigh scattering, water vapor
and ozone absorption, aerosol and cloud attenuation, and surface
reflection.

The surface net LW flux was obtained from surface downward solar flux
and in situ measured near-surface temperature using a statistical
algorithm described in Gu et al. (1997). The basic theory behind this
approach is that solar radiation provides the primary energy load
modulating the fundamental daily cycle of net LW flux. Variation of
surface temperature is the response of the surface to the incident solar
energy, which affects the net LW flux through its effect on upward LW
flux.

9.2 Data Processing Sequence

None given.

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

None given.

9.3.2 Calculated Variables

None given.

9.4 Graphs and Plots

None.

10\. Errors

10.1 Sources of Error

Potential sources of error include:

\-- Calibration

\-- Model parameterization: cloud optical properties, Rayleigh
scattering

\-- Uncertainties in input: column water vapor amount, aerosol optical
depth

\-- Quality of level-1 data

10.2 Quality Assessment

10.2.1 Data Validation by Source

The derived SW and LW images were compared with in situ measurements
taken during IFC-2 of 1994 at Automated Meteorological Stations (AMS).
See Gu and Smith (1997) and Gu et al. (1997) for details.

10.2.2 Confidence Level/Accuracy Judgment

Compared to the downward solar and PAR data measured at the AMS sites
during IFC-2 94, the rms errors (in W/m^2^) and relative rms errors in
(%) are:

downward solar downward PAR

\-\-\-\-\-\-\-\-\-\-\-\-\-- \-\-\-\-\-\-\-\-\-\-\--

all sky: 77.9 (19.0%) 35.7 (21.4%)

clear: 34.3 (6.49%) 16.6 (7.71%)

partly cloudy: 86.2 (19.3%) 35.6 (19.3%)

overcast/rain: 75.3 (35.8%) 42.5 (48.6%)

heavy smoke: 75.1 (21.1%) 43.8 (32.5%)

The mean differences in W/m^2^ (retrieved - AMS measured) are:

downward solar downward PAR

\-\-\-\-\-\-\-\-\-\-\-\-\-- \-\-\-\-\-\-\-\-\-\-\--

all sky: -6.7 10.9

clear: -8.2 6.3

partly cloudy: -11.0 6.6

overcast/rain: 6.1 25.0

heavy smoke: -1.2 19.8

The relative rms differences between the LW images and the in situ
measurements taken at the 10 AMS sites are under 40% of the mean
measured net LW flux. Note that the in situ measured net LW fluxes (L\*)
are calculated from measurements of net radiation (Rn) and net solar
radiation (K\*) i.e., L\* = Rn - K\*. Part of the rms differences may be
a consequence of differences in leveling between the net pyrradiometers
and albedometers mounted on some of the AMS towers (c.f. Gu et al.,
1997, for details).

10.2.3 Measurement Error for Parameters

See Section 11.2.

10.2.4 Additional Quality Assessments

None given.

10.2.5 Data Verification by Data Center

BORIS staff has viewed the imagery to verify image sizes, data type, and
format.

11\. Notes

11.1 Limitations of the Data

See Section 11.2.

11.2 Known Problems with the Data

The SW data overestimate both the broad-band and narrow-band surface
albedo. Depending on solar zenith angle and surface type, the broad-band
surface albedo is 5-30% larger than the albedometer measurements. This
is partly due to the single-scattering assumption made to simplify the
calculation of Rayleigh scattering. Adding in multiple scattering may
reduce the surface albedo at high and low solar zenith angles by \~ 2
and 5%, respectively.

The LW data values are high biased since we have used the near-surface
thermodynamic temperature to replace the radiometric skin temperature.
This is because there is only one thermal infrared channel in GOES-7
data, which is not sufficient to derive the radiometric temperature
within a certain limit of error. For 1996, we will use the surface
radiometric temperature retrieved from the split window of GOES-8 data.

11.3 Usage Guidance

None given.

11.4 Other Relevant Information

None given.

12\. Application of the Data Set

These data were derived for the purpose of using the radiation fields
for temporal and spatial modeling at regional scales.

13\. Future Modifications and Plans

The plans for an improved SW algorithm will include:

\-- improvement in parameterization for Rayleigh scattering

\-- surface bidirectional reflectance model developed for BOREAS

\-- bidirectional reflectance model for clouds

The plans for an improved LW algorithm will include:

\-- use of GOES-8 split window data to retrieve surface skin temperature

\-- addition of a nighttime algorithm

14\. Software

14.1 Software Description

There are README files and FORTRAN programs at our anonymous ftp site.
The FORTRAN programs can be used to read the header, the image, or the
lat-lon files.

14.2 Software Access

To get on our anonymous ftp site, type:

ftp metsat.met.fsu.edu

username: anonymous

password: your email address

cd boreas

\-- for SW parameters: cd V1_products

\-- for net LW flux: cd L_net_products

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

Oak Ridge, TN

\(865\) 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

The level-2 GOES-7 SW and LW data can be made available on 8-mm tapes or
Digital Archive Tapes (DAT).

16.2 Film Products

None.

16.3 Other Products

Although the inventory is contained on the BOREAS CD-ROM set, the actual
GOES-7 images are not. See Section 15 for information about how to
obtain the data.

17\. References

17.1 Platform/Sensor/Instrument/Data Processing Documentation

Bobotek, A., A.S. Hechtman, R.J. Komajoa, and P.G. Woolner. July 1995.
GOES I-M System description. MITRE Corporation.

Kelly, K.A. 1989. GOES I-M image navigation and registration and user
Earth location. GOES I-M Operational Satellite Conf., Arlington, VA, US.
Department of Commerce, NOAA, 154-167.

Rossow, W.B., C.L. Brest, and M. Roiter. 1996. International Satellite
Cloud Climatology Project (ISCCP) New Radiance Calibrations. WMO/TD-No.
736. World Meteorological Organization.

Rossow, W.B., C.L. Brest, and M.D. Roiter. 1995. International Satellite
Cloud Climatology Project (ISCCP): Update of radiance calibration
report. Technical Document, World Climate Research Programme (ICSU and
WMO), Geneva, Switzerland, 76 pp.

Rossow, W.B., Y. Desormeaux, C.L. Brest, and A. Walker. 1992.
International Satellite Cloud Climatology Project (ISCCP): Radiance
calibration report. WMO/Technical Document No. 520, World Climate
Research Programme and World Meteorological Organization (ICSU and WMO),
Geneva, Switzerland, 104 pp.

17.2 Journal Articles and Study Reports

Gu, J. and E.A. Smith. 1997. High-resolution estimates of total solar
and PAR surface fluxes over large-scale BOREAS study area from GOES
measurements. Journal of Geophysical Research 102(D24):29,685-29,705.

Gu, J., E.A. Smith, G. Hodges, and H.J. Cooper. 1997. Retrieval of
Daytime Surface Net Longwave Flux over BOREAS from GOES Estimates of
Surface Solar Flux and Surface Temperature. Submitted to Canadian
Journal of Remote Sensing.

Newcomer, J., D. Landis, S. Conrad, S. Curd, K. Huemmrich, D. Knapp, A.
Morrell, J. Nickeson, A. Papagno, D. Rinker, R. Strub, T. Twine, F.
Hall, and P. Sellers, eds. 2000. Collected Data of The Boreal
Ecosystem-Atmosphere Study. NASA. CD-ROM.

Rossow, W.B., C.L. Brest, and M.D. Rotier. 1995. International satellite
cloud climatology project (ISCCP): Update of radiance calibration.
Technical Document, World Climate Research Program (ICSU and WMO),
Geneva, Switzerland, 76 pp.

Sellers, P. and F. Hall. 1994. Boreal Ecosystem-Atmosphere Study:
Experiment Plan. Version 1994-3.0, NASA BOREAS Report (EXPLAN 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. 1996. Boreal
Ecosystem-Atmosphere Study: 1994 Operations. NASA BOREAS Report (OPS DOC
94).

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

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.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.

17.3 Archive/DBMS Usage Documentation

None.

18\. Glossary of Terms

None given.

19\. List of Acronyms

AOCS - Attitude and Orbit Control System

ASCII - American Standard Code for Information Interchange

ATS - Applications Technology Satellite

BB - Broad-Band

BOREAS - BOReal Ecosystem-Atmosphere Study

BORIS - BOREAS Information System

BPI - Bytes Per Inch

CCT - Computer Compatible Tape

CDA - Command and Data Acquisition

CD-ROM - Compact Disk-Read-Only Memory

DAAC - Distributed Active Archive Center

DAT - Digital Archive Tape

EOS - Earth Observing System

EOSDIS - EOS Data and Information System

FFC - Focused Field Campaign

FOV - Field of View

FSU - Florida State University

GIS - Geographic Information System

GMT - Greenwich Mean Time

GOES - Geostationary Operational Environmental Satellite

GSFC - Goddard Space Flight Center

GVAR - GOES VARiable

IFC - Intensive Field Campaign

IFOV - Instantaneous Field of View

IIFC - Inter IFC

ISCCP - International Satellite Cloud Climatology Project

LW - Longwave

NAD83 - North American Datum of 1983

NASA - National Aeronautics and Space Administration

NB - Narrow-Band

NESDIS - National Environmental Satellite, Data and Information Service

NLUT - Normalization Look-Up Table

NOAA - National Oceanic and Atmospheric Administration

N-S - North-South

NSA - Northern Study Area

NWS - National Weather Service

ORNL - Oak Ridge National Laboratory

PANP - Prince Albert National Park

PAR - Photosynthetically Active Radiation

PMT - Photomultiplier Tube

RSS - Remote Sensing Science

SBRS - Santa Barbara Remote Sensing

SMS - Synchronous Meteorological Satellite

SRB - Surface Radiation Budget

SSA - Southern Study Area

SW - Shortwave

TOA - Top of the Atmosphere

URL - Uniform Resource Locator

VAS - VISSR Atmospheric Sounder

VISSR - Visible and Infrared Spin-Scan Radiometer

20\. Document Information

20.1 Document Revision Dates

Written: 21-Feb-1997

Last Updated: 29-Sep-1999

20.2 Document Review Dates

BORIS Review: 23-Sep-1998

Science Review:

20.3 Document ID

20.4 Citation

When using these data, please include the following acknowledgment as
well as citations of relevant papers in Section 17.2:

> The SRB data were provided by E.A. Smith and J. Gu of the Department
> of Meteorology, FSU.

If using data from the BOREAS CD-ROM series, also reference the data as:

> Smith, E.A., \"Surface Radiation Budget Retrieved from GOES-7 VISSR
> Imagery for Large Scale BOREAS Area.\" In Collected Data of The Boreal
> Ecosystem-Atmosphere Study. Eds. J. Newcomer, D. Landis, S. Conrad, S.
> Curd, K. Huemmrich, D. Knapp, A. Morrell, J. Nickeson, A. Papagno, D.
> Rinker, R. Strub, T. Twine, F. Hall, and P. Sellers. CD-ROM. NASA,
> 2000.

Also, cite the BOREAS CD-ROM set as:

> Newcomer, J., D. Landis, S. Conrad, S. Curd, K. Huemmrich, D. Knapp,
> A. Morrell, J. Nickeson, A. Papagno, D. Rinker, R. Strub, T. Twine, F.
> Hall, and P. Sellers, eds. Collected Data of The Boreal
> Ecosystem-Atmosphere Study. NASA. CD-ROM. NASA, 2000.

20.5 Document Curator

20.6 Document URL

Keywords:

GOES-7

Emitted Radiation

Reflected Radiation

Water Vapor