Sevilleta National Wildlife Refuge, near Albuquerque, New Mexico

\log

12/03/97 - Date this file created. G. Shore.
12/20/97 - Updated documentation. G. Shore.
10/30/01 - Added date/time fields to APPENDIX II section. G. Shore.


\doc

##############################################################
DATA SET CODE AND TITLE

SEV031 AVHRR Biweekly Composites (1992)


##############################################################
ABSTRACT
This dataset contains 21 separate 14-day composited AVHRR
images for 1992 clipped approximatedly to the New Mexico State
boundaries (plus 50 Km buffer around boundary). These were
obtained from the U.S. Geological Survey's EROS Data Center (EDC),
National Mapping Division, from the "CONTERMINOUS U.S. AVHRR BIWEEKLY
COMPOSITES" CD product series.


##############################################################
KEYWORDS
SEV031 AVHRR Advanced_Very_High_Resolution_Radiometer NOAA Satellite_Imagery Remote_Sensing USGS_EROS_Data_Center 1992


##############################################################
TABLE OF CONTENTS
I. WHY THE DATA WERE COLLECTED
II. WHEN THE DATA WERE COLLECTED
III. WHO IS INVOLVED WITH THE DATA
IV. WHERE TH DATA WERE COLLECTED
V. HOW THE DATA WERE COLLECTED AND PROCESSED BY THE USGS EDC
VI. HOW THE DATA WERE PROCESSED BY THE SEVILLETA IMS (SIMS)
VII. APPENDIX I - USGS EDC Metadata
VIII. APPENDIX II - Pixel Date Attribute Table


##############################################################
I. WHY THE DATA WERE COLLECTED

See the U.S. Geological Survey's EROS Data Center (EDC)
documentation in APPENDIX I below.


##############################################################
II. WHEN THE DATA WERE COLLECTED

Twenty-one 14-day composites for 1992. See the U.S. Geological
Survey's EROS Data Center (EDC) documentation in APPENDIX I below
for specific composite periods.


##############################################################
III. WHO IS INVOLVED WITH THE DATA

SOURCE AGENCY CONTACTS:
See the U.S. Geological Survey's EROS Data Center (EDC) documentation
in APPENDIX I below for USGS EDC contacts.

LOCAL SEVILLETA LTER CONTACTS:
Primary contact:
Greg Shore, Sevilleta LTER (gshore@sevilleta.unm.edu).

Principle investigators:
Bruce Milne, Sevilleta LTER (bmilne@sevilleta.unm.edu)

GIS/GPS specialist:
Greg Shore, Sevilleta LTER (gshore@sevilleta.unm.edu).

Data Management
Greg Shore, Sevilleta LTER (gshore@sevilleta.unm.edu)


##############################################################
IV. WHERE THE DATA WERE COLLECTED

The original biweekly composited images covered the
Conterminous United States. However, the images were clipped
to the approximate New Mexico State boundaries (plus 50 Km buffer
around boundary) for online access purposes, while the full U.S.
scenes are stored offline on tape. The clipping coordinates were
selected to perform exact clipping, so no resampling was required.
The approximate online (NM clipped) boundaries are:

Latitude/Longitude, decimal degrees (Clarke 1866 spheroid)
XMIN: -109.515170 YMIN 30.759247 XMAX -102.454601 YMAX 37.817184

Lambert Azimuthal Equal-area (see EDC document for projection info)
XMIN: -914000 YMIN -1529000 XMAX -216000 YMAX -795000

The source and the clipped images are in the following map projection:
Lambert Azimuthal Equal Area projection
Parameters:
Radius of sphere 6,370,997.0 meters
Longitude of central meridian 100 00 00 West
Latitude of origin 45 00 00 North
False easting 0
False northing 0
Units of measure meters
Pixel size 1,000 meters

Each clipped image has 735 rows and 699 columns, and has a cell size
of 1000 x 1000 m.

See the U.S. Geological Survey's EROS Data Center (EDC) documentation
in APPENDIX I below for spatial extent, projection information, etc.,
related to the full Conterminous US scenes.


##############################################################
V. HOW THE DATA WERE COLLECTED AND PROCESSED BY THE USGS EDC

See the U.S. Geological Survey's EROS Data Center (EDC)
documentation in APPENDIX I below.


##############################################################
VI. HOW THE DATA WERE PROCESSED BY THE SEVILLETA IMS (SIMS)

The general SIMS processing steps for each biweekly composite
period were to read the 10 image bands off the source USGS-EDC CD,
concatenate/import them into a 10-band ERDAS Imagine format image
file, georegister to the USGS-EDC specifications, clip the scene
to the approximate New Mexico State boundaries, move the clipped
scene to the online SIMS archive, and write the full scene to
offline tape.

The band order in the archived scenes is:

1- NOAA CHANNEL 1 6- NDVI
2- NOAA CHANNEL 2 7- SATELLITE ZENITH
3- NOAA CHANNEL 3 8- SOLAR ZENITH
4- NOAA CHANNEL 4 9- RELATIVE AZIMUTH
5- NOAA CHANNEL 5 10- DATE

The bands are described in detail in the U.S. Geological Survey's
EROS Data Center (EDC) documentation in APPENDIX I below. The
attribute data for the "DATE" band is found in APPENDIX II below.

A more precise description of the processing steps is as follows:

1. Mount AVHRR CD

2. Read the 10 bands of information off the CD for each biweekly composited
scene, concatenate 21 NULL bytes onto the last line of each band, concatenate
the 10 bands into a single file, then import as an ERDAS Imagine 10-band
image file (of size 2889 rows x 4587 cols). This process was automated
with the C-shell script:

/db/local/imagery/bincom/avhrr_import.csh 92

NOTE: this generates 10-band ERDAS Imagine format files, that are of
image size 2889 rows x 4587 cols, with filenames as follows:

avhrr92pPP.img

where: PP = bi-weekly growth period number

and bands in following order::
1- NOAA CHANNEL 1 6- NDVI
2- NOAA CHANNEL 2 7- SATELLITE ZENITH
3- NOAA CHANNEL 3 8- SOLAR ZENITH
4- NOAA CHANNEL 4 9- RELATIVE AZIMUTH
5- NOAA CHANNEL 5 10- DATE

3. Georegister the scene as follows:
Bring up ERDAS Imagine GUI, then Tools->ImageInfo tool and do:
1. File->Open->avhrr92pPP.img
2. Edit->Change Map Model:
a. Upper Left X: -2050000
b. Upper Left Y: 752000
c. Pixel Size X: 1000
d. Pixel Size Y: 1000
e. Units: meters
f. Projection: Lambert Azimuthal Equal-area
NOTE: click OK, then answer "Yes" to changing Map Model in all layers.
3. Edit->Add/Change Projection:
a. Spheroid Name: Sphere of Radius 6370997m
b. Datum Name: Undefined
c. Longitude of center of projection: 100:00:00 W
d. Latitude of center of projection: 45:00:00 N
e. False easting: 0.0 meters
f. False northing: 0.0 meters
NOTE: click OK, then answer "Yes" to changing Map Model in all layers.
4. Edit->Change Layer Name:
a. Change bands 1 - 5 to Channel_1, Channel_2, ..., Channel_5,respectively
b. Change band 6 to NDVI
c. Change bands 7 - 10 to SATELLITE_ZENITH, SOLAR ZENITH,
RELATIVE_AZIMUTH, and DATE, respectively

4. Clip full-scene to New Mexico minimum bounding box (+50 Km buffer) with
coordinates ULx = -914000, ULy = -795000, LRx = -216000, LRy = -1529000,
and dimensions 735 rows x 699 columns. This process was automated with
the C-shell scripts:

/db/local/imagery/bincom/batch_avhrr_clip2nm.csh, which calls:
/db/local/imagery/bincom/avhrr_clip2nm.csh avhrr92pPP.img avhrr92pPPnm.img

NOTE: this generates 10-band ERDAS Imagine format files, that are of
image size 735 rows x 699 cols, with filenames as follows:

avhrr92pPPnm.img

5. Unix compress the NM clipped image, make an archive directory, and move it
to the archive destination (/db/archive/imagery/avhrr/avhrr92pPP/). This
process was automated with the C-shell scripts:

/db/local/imagery/bincom/avhrr_archive.csh

NOTE: this generates Unix compressed files with filenames as follows:

avhrr92pPPnm.img.Z

6. Compress (gzip) and archive the full scene image to 4mm DAT tape, then
remove from online disk:

gzip avhrr92pPP.img
mt -f /dev/rmt/0cn fsf <#>
tar cvf /dev/rmt/0cn avhrr92pPP.img.gz
rm avhrr92pPP.img.gz

7. Copy the most current yearly "USGS-EDC-AVHRR Dataset README" file off CD for
inclusion in the online SIMS IAF metadata file (avhrr92.dbf) for the images
(note, must also convert from DOS to Unix file):

dos2unix /cdrom/cdrom0/readme.1st avhrr92readme.1st

8. Copy the "Date of Acquisition by Pixel" attribute file off each CD, then
split by biweekly period for inclusion in GIS/RS Metadata Abstract file
(avhrr92pPPnm.mda), and merge by year for inclusion in SIMS IAF metadata
file (avhrr92.dbf):

dos2unix /cdrom/cdrom0/geom/date.att avhrr92pPP-PPdate.att

/db/local/imagery/bincom/batch_avhrr_split_dateatt.csh, which calls:
/db/local/imagery/bincom/avhrr_split_dateatt.csh

/db/local/imagery/bincom/avhrr_concat_dates.csh 92 > avhrr92date.att

9. Generate (this) SIMS IAF metadata file (i.e., avhrr92.dbf) using template
file (avhrr_dbf.tmpl), appending readme file (avhrr92readme.1st), and date
file (avhrr92date.att).

10. Generate GIS/RS Metadata Abstract file for each image, and put with
image in appropriate directory (/db/archive/imagery/avhrr/avhrr92pPP/):

/db/local/imagery/bincom/get_avhrr_dates.csh 92 avhrr92.dbf 97 \
> avhrr92periods.txt

/db/local/imagery/bincom/batch_make_avhrr_abstract.csh avhrr92periods.txt
which calls:
/db/local/imagery/bincom/make_avhrr_abstract.csh


##############################################################
VII. APPENDIX I - USGS EDC Metadata

THE 1992 CONTERMINOUS U.S. AVHRR BIWEEKLY COMPOSITES
TABLE OF CONTENTS

Introduction . . . . . . . . . . . . . . . . . . . . . . . .Page 2

Data Set Characteristics . . . . . . . . . . . . . . . . . . . . 3

Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Scene Selection . . . . . . . . . . . . . . . . . . . . . . . 4
Satellite and Solar Viewing Geometry. . . . . . . . . . . . . 4
Radiometric Calibration . . . . . . . . . . . . . . . . . . . 5
Normalized Difference Vegetation Index. . . . . . . . . . . . 6
Date of Acquisition . . . . . . . . . . . . . . . . . . . . . 6
Geometric Registration. . . . . . . . . . . . . . . . . . . . 6
Compositing . . . . . . . . . . . . . . . . . . . . . . . . . 8
Miscellaneous Data. . . . . . . . . . . . . . . . . . . . . . 9

CD-ROM Organization. . . . . . . . . . . . . . . . . . . . . . .11

References . . . . . . . . . . . . . . . . . . . . . . . . . . .15



THE 1992 CONTERMINOUS U.S. AVHRR BIWEEKLY COMPOSITES
INTRODUCTION

In 1987, the U.S. Geological Survey's EROS Data Center (EDC), in Sioux Falls,
South Dakota, began receiving Advanced Very High Resolution Radiometer (AVHRR)
data from NOAA polar-orbiting satellites. The central location of the EDC in
the United States enables direct reception of all AVHRR overpasses of the
lower 48 States, as well as much of Canada and Mexico. Early in the 1990
growing season the EDC started acquiring NOAA-11 AVHRR 1-km resolution daily
observations to produce weekly and biweekly maximum normalized difference
vegetation index (NDVI) composites of the conterminous United States
(Eidenshink, 1992). The objective of the vegetation mapping program is to
compile, annually, a comprehensive series of calibrated, georegistered, daily
observations and biweekly maximum NDVI composites. These data are being
published on CD-ROM for easy distribution of the data set. These data sets
can be used in environmental monitoring and global climate change studies.

The vegetation diversity of the conterminous United States provides
opportunities for using both AVHRR data and the NDVI for monitoring vegetation
condition in several different ecosystems, including forests, agricultural
crops, and grasslands. The data set provides a comprehensive growing season
profile of these ecosystems, is extremely useful for assessing seasonal
variations in vegetation condition, and provides a foundation for studying
long-term changes resulting from human or natural factors.


DATA SET CHARACTERISTICS

The data set is composed of twenty-one 14-day maximum NDVI composites that were
created from nearly 400 NOAA-11 images and three single date images. The 17
core composite periods represent a continuous period from March 6, 1992, to
October 29, 1992. The first two (periods 1 and 2) and last two (periods 20
and 21) composites represent a 2-week period each for January, February,
November, and December. The 1992 data set is available as six CD-ROM's.
Each of the first five discs has four biweekly composites and miscellaneous
data which are described later in this file. The sixth disc of the 1992
CD-ROM series contains a December two-week composite; one daily and eight
twice-daily observation AVHRR scenes selected within an eight hour time
frame from August 22, 1992 to August 26, 1992 of Hurrricane Andrew; and the
NDVI statistics of all counties in the conterminous United States for each
composite period. The nine observations of Hurricane Andrew are identified
and described on the sixth disc.

Each 14-day composite includes 10 bands of information: AVHRR channels 1-5,
NDVI, satellite zenith, solar zenith, relative azimuth and a 10th band,
which is a pointer to identify the date of the source daily observation scene.
The daily observations have been calibrated to reflectance, scaled to byte
data, and geometrically registered to the Lambert Azimuthal Equal Area map
projection. The data for each pixel in the composite are extracted from the
daily observation scene on the basis of the maximum NDVI compositing process.


The 14-day composite periods for 1992 were:

____________________________________________________
Period Date of coverage Julian day
____________________________________________________

1 01/10 - 01/23/1992 010 - 023
2 01/31 - 02/13/1992 031 - 044
3 03/06 - 03/19/1992 066 - 079
4 03/20 - 04/02/1992 080 - 093
5 04/03 - 04/16/1992 094 - 107
6 04/17 - 04/30/1992 108 - 121
7 05/01 - 05/14/1992 122 - 135
8 05/15 - 05/28/1992 136 - 149
9 05/29 - 06/11/1992 150 - 163
10 06/12 - 06/25/1992 164 - 177
11 06/26 - 07/09/1992 178 - 191
12 07/10 - 07/23/1992 192 - 205
13 07/24 - 08/06/1992 206 - 219
14 08/07 - 08/20/1992 220 - 233
15 08/21 - 09/03/1992 234 - 247
16 09/04 - 09/17/1992 248 - 261
17 09/18 - 10/01/1992 262 - 275
18 10/02 - 10/15/1992 276 - 289
19 10/16 - 10/29/1992 290 - 303
20 11/13 - 11/26/1992 318 - 331
21 12/11 - 12/24/1992 346 - 359
____________________________________________________

The image dimensions of each band are 2,889 lines and 4,608 samples (13 mega-
bytes).



The nine observation scenes for Hurricane Andrew include channels 1 and 2 of
the AVHRR visible and near-infrared bands.

The Hurricane Andrew nine observation scenes were:

________________________________________________________________
DO Scene ID Description
________________________________________________________________
D01 AH12082292125312 Atantic Ocean, East of Florida
D02 AH12082392123150 Florida East Coastline **
D03 AH11082392205306 Southwest Eastern Coastline
D04 AH12082492134949 Over Florida Coastline
D05 AH11082492204122 Gulf of Mexico - West of Florida
D06 AH12082592132834 South of New Orleans
D07 AH11082592202922 Southwest of New Orleans Coastline
D08 AH12082692130734 Morgan City -Bearing North **
D09 AH11082692201723 Louisiana
_________________________________________________________________

** land scenes

PROCEDURES

The sections that follow describe the data processing flow that was used at
the EDC to create a composite data set. All image processing was conducted
using Land Analysis System (Ailts and others, 1990) software.


Scene Selection

Cloud-free AVHRR observations of the land surface are necessary for
monitoring the vegetation conditions. A single AVHRR overpass is seldom
completely cloud free. Holben (1986) showed that compositing AVHRR data
acquired over several days produces spatially continuous cloud-free images
over large areas with sufficient temporal resolution to study green vegetation
dynamics. The duration of consecutive daily observations is called the
compositing period. On a daily basis during a composite period, each
observation of NOAA-11 data over the conterminous United States was evaluated
for cloud cover. Typically, there are two satellite overpasses per day, one
over the eastern portion of North America and a second pass over the western
part of the continent. Every image that provided a clear observation of a
large ground surface area at reasonable nadir viewing angles is included in
the composite. On an average, 18 daily observations per biweekly period are
included in the composite.


Satellite and Solar Viewing Geometry

The availability of the viewing geometry information allows studies on
the effects of off-nadir viewing and the investigation of potential data
correction techniques. The solar zenith angle is used during the calibration
process to correct the solar illumination variability along an orbit.

The computation of the solar and satellite geometry is a process that
derives the satellite zenith, solar zenith, and relative azimuth angle for
each image pixel. The relative azimuth is the absolute difference between the
satellite and solar azimuth angles. The computed angles do not exceed 180
degrees. A separate image band is created for each of these three angle
computations.

The satellite zenith angle is computed in degrees, in which nadir is represented
as 90 degrees. Therefore, values less than 90 degrees represent view angles
in the backscattered (easterly) direction and values greater than 90 represent
the forward scatter (westerly) direction. Note that the effective field of
view of the satellite is approximately 55 degrees each side of nadir, but
computed satellite zenith angles can exceed 55 degrees because of the
curvature of the Earth.

The relative azimuth angle is computed as the absolute difference between the
solar azimuth and the satellite azimuth angles. The computed values are in
the 0 - 180 range. The relative azimuth angle is computed instead of separate
azimuth angles because only the absolute difference between the azimuth angles
is required for atmospheric correction algorithms. Also, saving only the
computed relative azimuth angle requires only one band in a daily observation
and composite image instead of two, which reduces the image storage require-
ments on CD-ROM.

Radiometric Calibration

Radiometric calibration of the AVHRR visible and near-infrared channels
(channels 1 and 2) is an important consideration because there is poor
preflight calibration, no onboard calibration, and difficulty with inflight
calibration. Preflight calibration coefficients can change while the
instrument is in storage or after launch because of the space environment.
Degradation of AVHRR sensors after launch has been well documented (Rao, 1987;
Price, 1987; Holben and others, 1990). Several studies have used stable sites
such as homogeneous desert targets to monitor the degradation of the sensors
after the satellite had been launched. Corrections are made for sensor
degradation by using coefficients developed from a study by Teillet and
Holben (1992) [unpublished report]. Their calculation takes into account the
desert calibration approach (Holben and others, 1990) to develop a set of
time-dependent calibration coefficients for the AVHRR sensor on NOAA-11. The
time-dependent coefficients are based on a piecewise linear fit of the desert
results. Piecewise linear fits are recommended for operational use because,
unlike polynomial fits, they will not change retroactively when new data are
added to the end of the time series.

In addition to radiometric calibration, the solar illumination variability,
which occurs in the north/south direction within an orbit, was corrected using
the cosine of the solar zenith angle. The calibration and solar illumination
correction of channels 1 and 2 was completed using the following formula:

R = (d*d/z)*kb(c-C)
where:
R is reflectance,
d is the mean earth-sun distance in astronomical units,
z is the cosine of the solar zenith angle,
k is the mean solar flux,
b is the gain coefficient,
c is the digital count, and
C is the deep space digital counts.

Reflectance values for channels 1 and 2 were converted to byte data, where
the range 0 - 254 represents 0 to 63.5 percent reflectance (0.25 percent per
bin) and the value 255 is a grouping of reflectance values greater than 63.5
percent. Any feature with greater than 63 percent reflectance is a cloud,
snow, or other bright non-vegetated surface.

The calibration coefficients for AVHRR thermal channels 3,4, and 5 are derived
onboard the satellite using a view of a stable blackbody and deep space as a
reference (Kidwell, 1991). The calibration process converts raw data values
to energy (milliwatts/m2-steradians-cm-1) using the following formula:

E=a+bc
where:
E is energy,
a is the intercept,
b is the gain coefficient, and
c is the digital count.

Energy is converted to brightness temperature using the inverse of Planck's
radiation function. The brightness temperatures are represented in Kelvin
units. A scaling factor was used to convert the brightness temperatures to
byte data. A scaling factor of 202.5 is subtracted from the brightness
temperature value and the difference is multiplied by 2 to maintain one half
percent accuracy (i.e., a brightness temperature of 280 becomes 155).

Normalized Difference Vegetation Index (NDVI)

The NDVI is the difference of near-infrared (channel 2) and visible
(channel 1) reflectance values normalized over the sum of channels 1 and 2
((NIR-VIS)/NIR+VIS). The NDVI equation produces values in the range of -1.0
to 1.0, where increasing positive values indicate increasing green vegetation
and negative values indicate nonvegetated surface features such as water,
barren, ice, snow, or clouds. The NDVI can be derived at several points in
the processing flow. To retain the most precision, the NDVI is derived after
calibration of channels 1 and 2, prior to scaling to byte range. Computation
of the NDVI must precede geometric registration and resampling to maintain
precision in this calculation.

To scale the computed NDVI results to byte data range, the NDVI computed
value, which ranges from -1.0 to 1.0, is scaled to the range of 0 to 200,
where computed -1.0 equals 0, computed 0 equals 100, and computed 1.0 equals
200. As a result, NDVI values less than 100 now represent clouds, snow,
water, and other nonvegetative surfaces and values greater than 100
represent vegetative surfaces.


Date of Acquisition

The date of acquisition images are provided to allow a user to identify the
specific daily observation used for each pixel. The date images for each
composite identify each daily input image as a unique value. The unique value
is linked to an inventory of the daily observations. A complete list of daily
observations used in each composite period is on this CD-ROM under the \GEOM
directory in file DATE.ATT. The Hurricane Andrew observations list is the
\ANDREW directory file DATE.ATT.


Geometric Registration

The process of compositing daily observations for each biweekly period required
each daily overpass to be registered to a common map projection to ensure that,
from day to day, each 1-km pixel represented the same ground location. The map
projection chosen for the data is the Lambert Azimuthal Equal Area. This
projection is appropriate for the North American Continent because of its
visual presentation and equal area characteristic, which allows easy measure-
ment of area throughout the data set.

To perform the image-to-image registration of the data a base image was
developed as a reference. Tests have shown that the best way to prepare the
base image is to register individual daily orbits to an accurate base map.
The map base used is the hydrography layer of the U.S. Geological Survey
1:2,000,000-scale digital line graph (DLG). The features in the DLG data,
such as water bodies, rivers, and streams, are identifiable features in the
AVHRR 1-km data. The DLG are rasterized to 1-km cells and registered to the
Lambert Azimuthal Equal Area map projection before being used as the map base
for the data.


Approximately 20 near-nadir cloud-free segments of NOAA-11 channel 2 daily
observations from the 1989 and 1990 growing season are manually registered to
the DLG data. Each segment is verified for accuracy (root-mean-square error
less than 1.0 pixel). The segments are digitally mosaicked to produce a
single base image of the conterminous United States for registering the 1992
growing season data. The accuracy of this base image is verified with a
root-mean-square error less than 1.0 pixel. Table 1 provides details on
projection parameters.


Table 1. Lambert Azimuthal Equal Area (LAZEA) projection
_______________________________________________________________

Parameters:
Radius of sphere 6,370,997.0 meters
Longitude of central meridian 100 00 00 West
Latitude of origin 45 00 00 North
False easting 0
False northing 0
Units of measure meters
Pixel size 1,000 meters

For the conterminous United States (1992)
Center of pixel (1,1) ( -2050000, 752000 )
Number of lines 2,889
Number of samples 4,587
LAZEA minimum bounding rectangle:
In projection meters:
Lower left ( -2050500, -2136500 )
Upper left ( -2050500, 752500 )
Upper right ( 2536500, 752500 )
Lower right ( 2536500, -2136500 )

In decimal degrees of latitude and longitude:
Lower left ( -119.9722899 23.5837576 )
Upper left ( -128.5300591 48.4030555 )
Upper right ( -65.3946489 46.7048989 )
Lower right ( -75.4163527 22.4793919 )

In degrees, minutes, and seconds of latitude and longitude:
Lower left ( -119 58 20 23 35 02 )
Upper left ( -128 31 48 48 24 11 )
Upper right ( -65 23 41 46 42 18 )
Lower right ( -75 24 59 22 28 46 )
________________________________________________________________

Each daily observation for the 1992 growing season is registered to the base
image using image-to-image correlation. To improve overall registration
accuracy, 150 samples are eliminated from each edge of the raw data image.
The 150 samples represent the most extreme off-nadir pixels and are often the
source of error in the image correlation process. Then, the channel 2 data
for each daily observation are transformed using the satellite orbit model.
Next, correlation of the input image to the reference image is performed using
a set of 255 selected ground control points. If most of the ground control
points are cloud covered in the daily observation, no correlation is defined
and the image is rejected. Otherwise, the correlation is determined and the
satellite transformation coefficients form the orbital model are revised.
Then the raw data (channels 1 - 5), NDVI, and satellite geometry data are
transformed using the revised coefficients and nearest neighbor resampling.


Compositing

The method for determining the portion of each overpass to be included in
the composite image was to retain pixels having the highest NDVI values. The
NDVI was examined pixel by pixel for each overpass within the biweekly
compositing period to determine the maximum value.

The retention of the highest NDVI value reduces the number of cloud-contaminated
pixels because values for clouds and cloud shadows are generally less than 100
(in the byte-scaled data) and clear day observations of vegetated surfaces are
greater than 100 (in the byte-scaled data). The result is a near cloud-free
image that depicts the maximum vegetative greenness for the compositing period.

The output of the compositing process was a 10-band image that included the
maximum NDVI value for each pixel during the composite period, the channels 1-5
and satellite viewing geometry data from the chosen daily observations, and a
pointer value that identified the satellite overpass from which that pixel was
taken. Table 2 lists the data included in each of the 10 bands.

Table 2. Band description of composite images
_______________________________________________________________

Band Description | Band Description
---------------------------------------------------------------
1 AVHRR channel 1 | 6 NDVI
2 AVHRR channel 2 | 7 Satellite zenith
3 AVHRR channel 3 | 8 Solar zenith
4 AVHRR channel 4 | 9 Relative azimuth
5 AVHRR channel 5 | 10 Date
_______________________________________________________________

The date of acquisition pointer is provided to allow a user to identify the
specific AVHRR daily observation (satellite scene number) used for each pixel.
To determine the date and scene number, first identify the date pointer value
for the pixel within a composite period, then use the reference table in file
DATE.ATT to determine the scene number.

Miscellaneous Data

When displaying large areas with AVHRR data, an overlay or mask of familiar
linework, such as county boundaries, can be used as a location aid. Several
images are included in the \MISC directory to provide location information.
All of the linework images represent lines in raster format as 1-km cells.
These data sets include climatic division boundaries (CDLINES), major land
resource areas boundaries (LRALINES), and county boundaries (CTYLINES), and
water bodies (WATERMSK). The climatic division lines were digitized from
NOAA base maps. The county lines are a modified version of the 1:2,000,000
scale DLG data. The major land resource area boundaries were digitized from
the U.S. Department of Agriculture, Soil Conservation Service (1981) maps.

The linework in the CDLINES and LRALINES images is coded at the byte value 255.
In the CTYLINES image, the county boundaries identified by the coasts and
international borders are at value 253, the county borders that are coincident
with State borders are at value 254, and other county boundaries are at value
255. This variable coding provides the capability to display coastal, state,
or county boundaries from the same image. The water bodies image has two
unique identifiers. Water has a 0 value and land has a value of 1.


Also included are three raster polygon images that can be used in an overlay
process where histograms or descriptive statistics could be computed for the
NDVI values within a polygon. These images include counties (CTYPOLY), major
land resource areas (LRAPOLY), and climatic divisions (CDPOLY).

Each polygon is in raster format and has a unique numeric identifier. Images
that include more than 256 unique polygons are stored in I*2 integer (16 bit)
format.

The attribute information that identifies or characterizes each polygon is
included under the \MISC directory. The attributes for the major land
resource area polygons are in LRAPOLY.ATT. The fields in the file are
polyid -- the unique polygon identification number
mlra -- the major land resource area (MLRA) identification
code used by the Soil Conservation Service
lratext -- text description of the MLRA used by the Soil
Conservation Service
The unique polygon identification number for the climatic division polygons
can be parsed into the State and climatic division number within that State.
For example, climatic district one in Arizona is polygon number 401. The 4 is
the Federal Information Processing Standard (FIPS) State identification number
for Arizona, and the 01 identifies the polygon as division one. Climatic
district one in Oklahoma is polygon number 4001, where 40 is the FIPS State
code and 01 is division one.

The attributes for the county polygons are in CTYPOLY.ATT. The fields in the
file are
cntyid -- the unique polygon identification number
npixels -- the number of pixels in each county
FIPS -- the FIPS State and county code for each county
cname -- the county name
sname -- the state name

One of the standard products calculated from the conterminous U.S. AVHRR data
set is a statistical summary of the NDVI by county for each composite period.
The statistical summaries for all 1992 compositing periods are available on
the sixth disc. The statistical summary can be imported to a spreadsheet and
graphed to show seasonal NDVI profiles. The statistical summary is linked to
the CTYPOLY image by the key attribute CNTYID that is included in the
CTYPOLY.ATT. This summary can be merged with the CTYPOLY image for
representation in image form.

The statistical summary for each composite period is stored in separate tables
with a standard naming convention (CNTYP01.DAT is the table for period 1,
CNTYP02.DAT for period 2 and so on). These tables are 80-character ASCII files
with the following attributes and format:
___________________________________________________________________________

Col # Fortran stmt. Description Definition
___________________________________________________________________________
1- 4 i4 CNTYID Unique identifier for
each county polygon
5-10 1x,i5 FIPS FIPS code
11-18 1x,f7.2 MEAN Mean NDVI (with clouds,
water, negative NDVI not
counted)
19-22 1x,i3 %USED The portion of all pixels
in county which are counted.
23-30 1x,f7.3 SD Standard deviation
31-34 1x,i3 MIN Minimum value in county
35-38 1x,i3 MAX Maximum value in county
39-46 1x,f7.2 MEDIAN Median value
47-50 1x,i3 MODE Mode value
51-54 1x,i3 PERIOD # Composite period number
___________________________________________________________________________

The NDVI statistics are calculated for each county after clouded pixels, water
bodies, and negative NDVI values (the 0 - 100 range of the scaled NDVI) are
masked out. The cloud screening is done independently (and is not applied to
image data on the CD-ROM) by using a threshold value of 240 for the sum of
channels 1 and 2 (values greater than 240 are considered clouds). The cloud-
screening technique is not foolproof so an added indicator, the attribute
%USED, is also included. The attribute %USED represents the proportion of the
pixels in a county (excluding water bodies) that were counted in the
computation. A low value in this attribute can indicate cloud contamination.

Added to the miscellaneous image file was the surface water bodies mask.
These water bodies were separated using channel 2 from daily AVHRR scenes.
Cloud-free scenes were selected through a visual quality assessment of
imagery. After a threshold between land and water values was identified, a
binary mask was computed and the water bodies data was added to a land
characteristic data base. Approximately 50 AVHRR scenes were used to create
the mask. Unique numeric identifiers were used in the raster formatted
polygons - water has the value of 0 and land has the value of 1.



Table 3. A list of miscellaneous image file characteristics
__________________________________________________________

Name Type Bands Lines Samples
__________________________________________________________

LRAPOLY I*2 1 2,889 4,608
LRALINES Byte 1 2,889 4,608
CDPOLY I*2 1 2,889 4,608
CDLINES Byte 1 2,889 4,608
CTYPOLY I*2 1 2,889 4,608
CTYLINES Byte 1 2,889 4,608
WATERMSK Byte 1 2,889 4,608
__________________________________________________________

CD-ROM ORGANIZATION

A large volume of data was generated during the construction of this data base.
The data stored on each CD-ROM required ten 6,250-bpi magnetic tapes. The data
are organized in a directory structure that logically separates the data
components. This structure is:

README.1ST
\AVHRR
README \LABELS \IMAGES
\ANDREW
README \LABELS \IMAGES
\NDVI
README \LABELS \IMAGES
\GEOM
README \LABELS \IMAGES
\MISC
README \LABELS \IMAGES
\DEMO
README
\SOFTWARE
README

Each directory on the disc contains data that are similar in type. Each
directory also contains an ASCII text file (README) that details the contents
of the directory.

The data files and LAS header files (files with name extensions .DDR) are in
the \IMAGES subdirectories, and the image label files are in the \LABELS
subdirectories. The binary image files were put on the CD-ROM with a 512-byte
header record. This header record is used by the LAS image processing system.

To get a quick start looking at the image files, label files for each image
are included in the \LABELS directory using the same file name as the image
file it describes in the \IMAGES subdirectory. These label files were designed
for use by the public domain MS-DOS personal computer IMDISP image display
software developed by NASA's Jet Propulsion Laboratory in Pasadena, CA.
IMDISP users can access the images on this CD-ROM by selecting the image name
in the \LABELS subdirectory, which automatically accesses the header inform-
ation required by the software to retrieve the image data.

The actual data dimensions of each band are 2,889 lines and 4,587 samples
(13 megabytes), but the images are stored as 2,889 lines and 4,608 samples to
accommodate LAS software. The last 21 samples of each line are blank (zero)
to make each line a multiple of 512 as required by LAS, with the exception of
the last line. The images were generated on a UNIX-based system. On UNIX
systems, the portion of the last block does not exist; therefore, lines
1-2,888 contain 4,608 samples and line 2,889 has 4,587 samples. The Hurricane
Andrew actual data dimensions of each band are 3,510 lines and 5,000 samples
(18 megabytes), but the images are stored as 3,510 lines and 5,120 samples to
accommodate LAS software. The last 120 samples of each line are blank (zero)
following the line multiple of 512 as mentioned above. Thus, lines 1-3,509
contain 5,120 samples and line 3,510 has 5,000 samples.


The formula to calculate the number of disc blocks for an image in a UNIX
environment is

#image_bytes_line = #samps * #bytes_samp
#bytes_file_line = INT(((#image_bytes_line - 1) / 512) + 1) * 512
#bytes_file = (#lines * #bytes_file_line * #nbands) -
(#bytes_file_line - #image_bytes_line) + 512

The \AVHRR directory contains the five channels of AVHRR data associated with
the four biweekly composites on each CD-ROM. Each band of each biweekly
composite file is uniquely named using the convention
P01CH1.IMG
where P01 identifies composite period 1 and CH1 identifies the image as
channel 1. The image files are stored in the \IMAGES subdirectory.

The \ANDREW directory contains the nine AVHRR observations, channels 1 and 2.
These Hurricane Andrew observations on the sixth disc are named using the
same convention, with D01 refering to the first daily observation and D02-D09
the twice-daily observations. The image files are stored in the \IMAGES sub-
directory.

The \NDVI directory contains the single band computed NDVI for the biweekly
AVHRR composite data sets and is named using the convention:
P01NDVI.IMG
where P01 identifies composite period 1 and NDVI identifies the image as a
vegetation index image. The sixth disc contains the December two-week composite
period P21NDVI. The image files are stored in the \IMAGES subdirectory.

The \GEOM directory contains the satellite and solar zenith and relative azimuth
information for each pixel in the AVHRR composite images. This directory also
contains the date images for each of the composites, as well as the DATE.ATT
attribute file.

The \MISC directory contains the political (CTYLINES, CTYPOLY), climatic
divisions (CDLINES, CDPOLY), and land resource area (LRALINES, LRAPOLY) raster
line and polygon images, which are useful for display or in digital analysis
procedures. Attribute files related to these are included as files
CTYPOLY.ATT and LRAPOLY.ATT.

The \DEMO directory contains a batch job that runs under DOS and uses the
display program, IMDISP. This program displays images from the 1990
Conterminous U.S. AVHRR Biweekly Composites set. The display files are
compressed samples of these images. To initiate the demo program, just enter
"DEMO" at the DOS prompt.


The \SOFTWARE directory contains programs to allow the PC-DOS user to display
and interact with the digital images on the CD's. These public domain programs
include

IMDISP - An image display program developed by NASA's Jet Propulsion
Laboratory. The most recent version is included on this disc.
See the IMDISP documentation file IMDISP.DOC, located in the
\SOFTWARE directory, and use the IMDISP help command for further
details.

CONVERT - A conversion program included with IMDISP that allows the
conversion of a raster image to integer, byte, nibble, or
binary format.

COPIM - A copy program that allows copying all or portions of a
raster image and puts IMDISP compatible label records at
the front of the image.

COMPOSIT - A utility for combining or compositing two or more images as
a single new image. This utility has options to
1. Combine up to three separate images into a single new
black-and-white image and also create a customized color
palette of up to 255 colors that, along with the new
combined image, allows a color simulation of a 3-band
composite image suitable for display on an 8-bit PC color
monitor; these colors are a very close approximation of
how the image would appear on a 24-bit color display.
2. Automatically "stretch" or brighten an existing palette.
3. Embed one image (such as raster linework) within a
second image.
The resultant images and palettes created by the COMPOSIT
utility are compatible with the IMDISP display program. It
takes approximately 4 minutes to process a 512 lines by 512
samples, 3-image composite when the input and output images
are on hard disk. To run this utility type COMPOSIT and
respond to the prompts requesting the input image names,
output image name, and output palette name.

LL2LAM - Converts latitude and longitude coordinates to Lambert Azimuthal
Equal Area projection coordinates.

LAM2LL - Converts Lambert Azimuthal Equal Area projection coordinates to
latitude and longitude coordinates.

LL2LS - Converts latitude and longitude to line and sample coordinates in
the Conterminous U.S. AVHRR data set. This data set is in the
Lambert Azimuthal Equal Area projection.

LS2LL - Converts line and sample coordinates in the Conterminous U.S.
AVHRR data set to latitude and longitude.


There are no restrictions on making copies of IMDISP or any of the other
public domain programs for use on other PC's or with other raster images.
* NOTE: Prior to displaying any of the following images with IMDISP, the
command "SET SWAP" must be run to reset the display for 16-bit
integer data. This command must be run after the image has been
selected with the IMDISP "FILES" command.

CTYPOLY.LBL - County polygon data
CDPOLY.LBL - Climatic polygon data
LRAPOLY.LBL - LRA polygon data
DEM.LBL - Digital Elevation data




For more detailed technical information please contact Customer Services,
EROS Data Center, U.S. Geological Survey, Sioux Falls, SD 57198,
(605)594-6151, FAX (605)594-6589.

REFERENCES

Ailts, B., Akkerman, D., Quirk, B., and Steinwand, D., 1990, LAS 5.0 -- an
image processing system for research and production environments:
American Society for Photogrammetry and Remote Sensing-American Congress
on Surveying and Mapping Annual Convention, Denver, Colorado,
March 18-23, 1990 Proceedings, v. 4, p. 1-12.

Eidenshink, J.C., 1992, The 1990 conterminous U.S. AVHRR data set.

Photogrammetric Engineering and Remote Sensing, vol. 58, no. 6,
pp. 809-813.

Holben, B.N., 1986, Characteristics of maximum-value composite images from
temporal AVHRR data: The International Journal of Remote Sensing, v. 7,
no. 11, p. 1417.

Holben, B.N., Kaufman, Y.J., and Kendall, J.D., 1990, NOAA-11 AVHRR visible
and near-IR inflight calibration: The International Journal of Remote
Sensing, v. 11, no. 8, p. 1511.

Kidwell, K.B., 1991, NOAA Polar Orbiter Data Users' Guide: National Oceanic
and Atmospheric Administration, World Weather Building, Room 100,
Washington, D.C.

Price, John C., 1987, Calibration of satellite radiometers and the comparison
of vegetation indices: Remote Sensing of the Environment, v. 21, no.
15, pp. 15-27.

Rao, Nagaraja C. R., 1987, Pre-launch calibration of channels 1 and 2 of
Advanced Very High Resolution Radiometer: NOAA Technical Report NESDIS
36, Satellite Research Laboratory, National Environmental Satellite,
Data, and Information Service, Washington, D.C., 62 p.

Teillet, P.M. and Holben, B.N., 1991, unpublished report.

U.S. Department of Agriculture, Soil Conservation Service, 1981, Land resource
regions and major land resource areas of the United States: Agricultural
Handbook 296, 156 p.



Acknowledgements

A number of individuals contributed to the successful completion of the AVHRR
Conterminous U.S. composite data, including various operations staff and
digital data production scientists. Donna K. Scholz and Donald O. Ohlen
provided excellent technical reviews.

Jeffery C. Eidenshink

Michael E. Madigan


##############################################################
VIII. APPENDIX II - Pixel Date Attribute Table


PERIOD INDEX SCENEID Date GMT
------ ----- ---------------- ------- --------
1 1 ah11011092203412 01-10-92 20:34:12
2 ah11011092221735 01-10-92 22:17:35
3 ah11011192220508 01-11-92 22:05:08
4 ah11011392214033 01-13-92 21:40:33
5 ah11011492194750 01-14-92 19:47:50
6 ah11011492212830 01-14-92 21:28:30
7 ah11011592193623 01-15-92 19:36:23
8 ah11011192202226 01-11-92 20:22:26
9 ah11011292215242 01-12-92 21:52:42
10 ah11011592211623 01-15-92 21:16:23
11 ah11011692192458 01-16-92 19:24:58
12 ah11011692210432 01-16-92 21:04:32
13 ah11011692224951 01-16-92 22:49:51
14 ah11011792205227 01-17-92 20:52:27
15 ah11011792223705 01-17-92 22:37:05
16 ah11011892204038 01-18-92 20:40:38
17 ah11011892222420 01-18-92 22:24:20
18 ah11011992185104 01-19-92 18:51:04
19 ah11012192200533 01-21-92 20:05:33
20 ah11011992202849 01-19-92 20:28:49
21 ah11011992221137 01-19-92 22:11:37
22 ah11012092201721 01-20-92 20:17:21
23 ah11012192214659 01-21-92 21:46:59
24 ah11012292195409 01-22-92 19:54:09
25 ah11012292213454 01-22-92 21:34:54
26 ah11012392212245 01-23-92 21:22:45
2 101 ah11020792200622 02-07-92 20:06:22
102 ah11020792214746 02-07-92 21:47:46
103 ah11020892213536 02-08-92 21:35:36
104 ah11020992194308 02-09-92 19:43:08
105 ah11020892195452 02-08-92 19:54:52
106 ah11020992212326 02-09-92 21:23:26
107 ah11021092193140 02-10-92 19:31:40
108 ah11021092211133 02-10-92 21:11:33
109 ah11021192192030 02-11-92 19:20:30
110 ah11021292190904 02-12-92 19:09:04
113 ah11013192194846 01-31-92 19:48:46
114 ah11013192212926 01-31-92 21:29:26
115 ah11020192193719 02-01-92 19:37:19
116 ah11020192211718 02-01-92 21:17:18
117 ah11020292192553 02-02-92 19:25:53
118 ah11020292210526 02-02-92 21:05:26
119 ah11020292225045 02-02-92 22:50:45
120 ah11020392191429 02-03-92 19:14:29
121 ah11020392205321 02-03-92 20:53:21
122 ah11020492204128 02-04-92 20:41:28
123 ah11020492222510 02-04-92 22:25:10
124 ah11020592202954 02-05-92 20:29:54
125 ah11020592221226 02-05-92 22:12:26
126 ah11020692220013 02-06-92 22:00:13
127 ah11020392223744 02-03-92 22:37:44
128 ah11020592185154 02-05-92 18:51:54
129 ah11020692201808 02-06-92 20:18:08
3 1 ah11030692211641 03-06-92 21:16:41
2 ah11030992222352 03-09-92 22:23:52
3 ah11030992190224 03-09-92 19:02:24
4 ah11031092221137 03-10-92 22:11:37
5 ah11031192215904 03-11-92 21:59:04
6 ah11031292214647 03-12-92 21:46:47
7 ah11031092202856 03-10-92 20:28:56
8 ah11031192201718 03-11-92 20:17:18
101 ah11031492212216 03-14-92 21:22:16
102 ah11031392195352 03-13-92 19:53:52
103 ah11031592211017 03-15-92 21:10:17
104 ah11031692191913 03-16-92 19:19:13
105 ah11031792204614 03-17-92 20:46:14
106 ah11031992220447 03-19-92 22:04:47
107 ah11031992202242 03-19-92 20:22:42
108 ah11031392213431 03-13-92 21:34:31
109 ah11031492194217 03-14-92 19:42:17
110 ah11031892185635 03-18-92 18:56:35
4 1 ah11032092201050 03-20-92 20:10:50
2 ah11032192195914 03-21-92 19:59:14
3 ah11032292212742 03-22-92 21:27:42
4 ah11032092215214 03-20-92 21:52:14
5 ah11032392230136 03-23-92 23:01:36
6 ah11032392193552 03-23-92 19:35:52
7 ah11032492224822 03-24-92 22:48:22
8 ah11032492210326 03-24-92 21:03:26
9 ah11032492192415 03-24-92 19:24:15
10 ah11032592205128 03-25-92 20:51:28
11 ah11032392211543 03-23-92 21:15:43
101 ah11032792221000 03-27-92 22:10:00
102 ah11032792202737 03-27-92 20:27:37
103 ah11032892215740 03-28-92 21:57:40
104 ah11032892201557 03-28-92 20:15:57
105 ah11032992214506 03-29-92 21:45:06
106 ah11033092213303 03-30-92 21:33:03
107 ah11033092195227 03-30-92 19:52:27
108 ah11033192230734 03-31-92 23:07:34
109 ah11033192212053 03-31-92 21:20:53
110 ah11033192194058 03-31-92 19:40:58
111 ah11040192225353 04-01-92 22:53:53
112 ah11040192210853 04-01-92 21:08:53
113 ah11040292224058 04-02-92 22:40:58
114 ah11040292205639 04-02-92 20:56:39
5 1 ah11040392222804 04-03-92 22:28:04
2 ah11040392204440 04-03-92 20:44:40
3 ah11040392190633 04-03-92 19:06:33
4 ah11040492203244 04-04-92 20:32:44
5 ah11040592220250 04-05-92 22:02:50
6 ah11040592202104 04-05-92 20:21:04
7 ah11040692215029 04-06-92 21:50:29
8 ah11040792213820 04-07-92 21:38:20
9 ah11040892194603 04-08-92 19:46:03
10 ah11040892212602 04-08-92 21:26:02
11 ah11040992211401 04-09-92 21:14:01
101 ah11041092210146 04-10-92 21:01:46
102 ah11041092224624 04-10-92 22:46:24
103 ah11041292203748 04-12-92 20:37:48
104 ah11041392184848 04-13-92 18:48:48
105 ah11041292222035 04-12-92 22:20:35
106 ah11041392202553 04-13-92 20:25:53
107 ah11041492201423 04-14-92 20:14:23
108 ah11041492215547 04-14-92 21:55:47
109 ah11041592200229 04-15-92 20:02:29
110 ah11041592214328 04-15-92 21:43:28
102 ah11041092224624 04-10-92 22:46:24
111 ah11041492215547 04-14-92 21:55:47
6 1 ah11041792193916 04-17-92 19:39:16
2 ah11041892225150 04-18-92 22:51:50
3 ah11041992191623 04-19-92 19:16:23
4 ah11041992223854 04-19-92 22:38:54
5 ah11042092222600 04-20-92 22:26:00
6 ah11042192203104 04-21-92 20:31:04
7 ah11042192221328 04-21-92 22:13:28
8 ah11042292201924 04-22-92 20:19:24
9 ah11042292220107 04-22-92 22:01:07
10 ah11042392200730 04-23-92 20:07:30
11 ah11042392214847 04-23-92 21:48:47
101 ah11042492195552 04-24-92 19:55:52
102 ah11042492213629 04-24-92 21:36:29
103 ah11042592212411 04-25-92 21:24:11
104 ah11042692211210 04-26-92 21:12:10
105 ah11042692225726 04-26-92 22:57:26
106 ah11042792192106 04-27-92 19:21:06
107 ah11042792205955 04-27-92 20:59:55
108 ah11042792224414 04-27-92 22:44:14
109 ah11042892204757 04-28-92 20:47:57
110 ah11042892223121 04-28-92 22:31:21
103 ah11042592212411 04-25-92 21:24:11
104 ah11042692211210 04-26-92 21:12:10
111 ah11042992185833 04-29-92 18:58:33
112 ah11042992203601 04-29-92 20:36:01
113 ah11042992221843 04-29-92 22:18:43
114 ah11043092202419 04-30-92 20:24:19
115 ah11043092220606 04-30-92 22:06:06
107 ah11042792205955 04-27-92 20:59:55
108 ah11042792224414 04-27-92 22:44:14
109 ah11042892204757 04-28-92 20:47:57
7 1 ah11050492211706 05-04-92 21:17:06
2 ah11050192201224 05-01-92 20:12:24
1 ah11050492211706 05-04-92 21:17:06
2 ah11050192201224 05-01-92 20:12:24
3 ah11050192215345 05-01-92 21:53:45
4 ah11050292200046 05-02-92 20:00:46
5 ah11050292214126 05-02-92 21:41:26
6 ah11050392194908 05-03-92 19:49:08
7 ah11050392212908 05-03-92 21:29:08
8 ah11050492193732 05-04-92 19:37:32
9 ah11050492230240 05-04-92 23:02:40
10 ah11050592210450 05-05-92 21:04:50
11 ah11050592224928 05-05-92 22:49:28
12 ah11050692205250 05-06-92 20:52:50
13 ah11050692223632 05-06-92 22:36:32
14 ah11050792190306 05-07-92 19:03:06
15 ah11050792204051 05-07-92 20:40:51
16 ah11050792222353 05-07-92 22:23:53
101 ah11050892185151 05-08-92 18:51:51
102 ah11050892202910 05-08-92 20:29:10
103 ah11050892221116 05-08-92 22:11:16
104 ah11050992201715 05-09-92 20:17:15
105 ah11050992215839 05-09-92 21:58:39
106 ah11051092200535 05-10-92 20:05:35
107 ah11051092214619 05-10-92 21:46:19
108 ah11051192213400 05-11-92 21:34:00
109 ah11051292194203 05-12-92 19:42:03
110 ah11051292212155 05-12-92 21:21:55
111 ah11051292230804 05-12-92 23:08:04
112 ah11051392225435 05-13-92 22:54:35
113 ah11051492224138 05-14-92 22:41:38
114 ah11051492191907 05-14-92 19:19:07
8 1 ah11051592190734 05-15-92 19:07:34
2 ah11051592204538 05-15-92 20:45:38
3 ah11051592222843 05-15-92 22:28:43
4 ah11051692203340 05-16-92 20:33:40
5 ah11051692221604 05-16-92 22:16:04
6 ah11051792202158 05-17-92 20:21:58
7 ah11051792220341 05-17-92 22:03:41
8 ah11051892201002 05-18-92 20:10:02
9 ah11051992195827 05-19-92 19:58:27
10 ah11051992213903 05-19-92 21:39:03
11 ah11052092194648 05-20-92 19:46:48
12 ah11052192193511 05-21-92 19:35:11
13 ah11052192225942 05-21-92 22:59:42
101 ah11052292192336 05-22-92 19:23:36
102 ah11052292224644 05-22-92 22:46:44
103 ah11052392191216 05-23-92 19:12:16
104 ah11052392205024 05-23-92 20:50:24
105 ah11052392223347 05-23-92 22:33:47
106 ah11052492203825 05-24-92 20:38:25
107 ah11052492222108 05-24-92 22:21:08
108 ah11052592220829 05-25-92 22:08:29
109 ah11052892195133 05-28-92 19:51:33
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121 ah11122192201624 12-21-92 20:16:24
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124 ah11122292200439 12-22-92 20:04:39
125 ah11122392231641 12-23-92 23:16:41
126 ah11122392213203 12-23-92 21:32:03
127 ah11122492194131 12-24-92 19:41:31

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