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

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DATA SET CODE AND TITLE

SEV031 AVHRR Biweekly Composites (1993)


##############################################################
ABSTRACT
This dataset contains 21 separate 14-day composited AVHRR
images for 1993 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 1993


##############################################################
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 1993. 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 93

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

avhrr93pPP.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->avhrr93pPP.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 avhrr93pPP.img avhrr93pPPnm.img

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

avhrr93pPPnm.img

5. Unix compress the NM clipped image, make an archive directory, and move it
to the archive destination (/db/archive/imagery/avhrr/avhrr93pPP/). 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:

avhrr93pPPnm.img.Z

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

gzip avhrr93pPP.img
mt -f /dev/rmt/0cn fsf <#>
tar cvf /dev/rmt/0cn avhrr93pPP.img.gz
rm avhrr93pPP.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 (avhrr93.dbf) for the images
(note, must also convert from DOS to Unix file):

dos2unix /cdrom/cdrom0/readme.1st avhrr93readme.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
(avhrr93pPPnm.mda), and merge by year for inclusion in SIMS IAF metadata
file (avhrr93.dbf):

dos2unix /cdrom/cdrom0/geom/date.att avhrr93pPP-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 93 > avhrr93date.att

9. Generate (this) SIMS IAF metadata file (i.e., avhrr93.dbf) using template
file (avhrr_dbf.tmpl), appending readme file (avhrr93readme.1st), and date
file (avhrr93date.att).

10. Generate GIS/RS Metadata Abstract file for each image, and put with
image in appropriate directory (/db/archive/imagery/avhrr/avhrr93pPP/):

/db/local/imagery/bincom/get_avhrr_dates.csh 93 avhrr93.dbf 97 \
> avhrr93periods.txt

/db/local/imagery/bincom/batch_make_avhrr_abstract.csh avhrr93periods.txt
which calls:
/db/local/imagery/bincom/make_avhrr_abstract.csh


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

THE 1993 CONTERMINOUS U.S. AVHRR BIWEEKLY COMPOSITES

TABLE OF CONTENTS

Page
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Data Set Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Scene Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Satellite and Solar Viewing Geometry. . . . . . . . . . . . . . . . . . . 5
Radiometric Calibration . . . . . . . . . . . . . . . . . . . . . . . . . 6
Normalized Difference Vegetation Index. . . . . . . . . . . . . . . . . . 9
Date of Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Geometric Registration. . . . . . . . . . . . . . . . . . . . . . . . . .10
Compositing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Miscellaneous Data. . . . . . . . . . . . . . . . . . . . . . . . . . . .15

CD-ROM Organization. . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26


THE 1993 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 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 conditions, 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, created
from nearly 400 NOAA-11 images, and 3 single date images. The 17 core
composite periods represent a continuous period from March 5, 1993, to October
28, 1993. 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 1993 data set is available as a set of six CD-ROM's. Each of
the first five discs has four biweekly composites and miscellaneous data that
are described later in this file. The sixth disc of the 1993 CD-ROM series
contains the December 2-week composite, two daily observation AVHRR scenes
depicting the Mississippi River region of the United States. These observations
were chosen to represent the change that occurred from the 1993 Mississippi
River flooding. One observation is of July 17, 1992 before the flooding and
the other observation is of July 12, 1993 showing the flooding. These two
daily observations only have channels 1 and 2.

Each daily observation includes nine bands of information: AVHRR channels 1-5,
NDVI, satellite zenith, solar zenith, and relative azimuth. The daily
observations have been calibrated to reflectance, scaled to byte data, and
geometrically registered to the Lambert Azimuthal Equal Area map projection.

Each 14-day composite includes 10 bands of information, the 9 bands described
above for each daily observation and a 10th band, which is a pointer to
identify the date of the source daily observation scene. 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 1993 were:

____________________________________________________
Period Date of coverage Julian day
____________________________________________________

1 01/08 - 01/21/1993 008 - 021
2 02/12 - 02/25/1993 043 - 056
3 03/05 - 03/18/1993 064 - 077
4 03/19 - 04/01/1993 078 - 091
5 04/02 - 04/15/1993 092 - 105
6 04/16 - 04/29/1993 106 - 119
7 04/30 - 05/13/1993 120 - 133
8 05/14 - 05/27/1993 134 - 147
9 05/28 - 06/10/1993 148 - 161
10 06/11 - 06/24/1993 162 - 175
11 06/25 - 07/08/1993 176 - 189
12 07/09 - 07/22/1993 190 - 203
13 07/23 - 08/05/1993 204 - 217
14 08/06 - 08/19/1993 218 - 231
15 08/20 - 09/02/1993 232 - 245
16 09/03 - 09/16/1993 246 - 259
17 09/17 - 09/30/1993 260 - 273
18 10/01 - 10/14/1993 274 - 287
19 10/15 - 10/28/1993 288 - 301
20 11/12 - 11/25/1993 316 - 329
21 12/10 - 12/23/1993 344 - 357
____________________________________________________
The image dimensions of each band are 2,889 lines and 4,608 samples (13
megabytes).


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
requirements 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
(in press). 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 nonvegetated 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-steradian-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 equal to or 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 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.

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 measurement 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 data are rasterized to 1-km cells and registered to
the Lambert Azimuthal Equal Area 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 pixel). The segments are digitally mosaicked to produce a single
base image of the conterminous United States for registering the 1993 growing
season data. The accuracy of this base image is verified with a
root-mean-square error less than 1 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 (1993)
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 longitude and latitude:
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 longitude and latitude:
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 1993 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 original 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 from 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 equal to or 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 product 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), 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 1993 compositing periods are
available on the sixth disc. The statistical summary can be imported to a
spreadsheet and a graph can be created 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 includes an added indicator, the attribute %USED. 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 the
images. 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
\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,
California. IMDISP users can access the images on this CD-ROM by selecting
the image name in the \LABELS subdirectory, which automatically accesses the
header information 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 the 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 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 daily observations on the sixth disc are named using the same
convention, with D01 referring to the first daily observation. The image
files are stored in the \IMAGES subdirectory.

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 2-week composite
period P21NDVI and the three daily observations D01 - D03. 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), water bodies (WATERMSK), 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, 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.

COMBINE - A utility for combining 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 false color
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 COMBINE
utility are compatible with the IMDISP display program.
It takes approximately 4 minutes to process a 512 lines
by 512 samples, 3-image false color composite when the
input and output images are on hard disk. To run this
utility type COMBINE 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 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., in press, Towards operational radiometric
calibration of NOAA AVHRR imagery in the visible and infrared channels:
Canadian Journal of Remote Sensing.

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.


Acknowledgments

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. Jesslyn F. Brown and Richard A. McKinney
provided excellent technical reviews.



Jeffery C. Eidenshink

Michael E. Madigan

Mary C. Weinheimer


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


PERIOD INDEX SCENEID Date GMT
------ ----- ---------------- ------- --------
1 1 ah11011093211530 01-10-93 21:15:30
2 ah11010993212737 01-09-93 21:27:37
3 ah11011193224549 01-11-93 22:45:49
4 ah11011293205140 01-12-93 20:51:40
5 ah11011293223324 01-12-93 22:33:24
6 ah11011593201607 01-15-93 20:16:07
7 ah11011593215603 01-15-93 21:56:03
8 ah11011693200424 01-16-93 20:04:24
9 ah11011693214353 01-16-93 21:43:53
10 ah11011793195242 01-17-93 19:52:42
11 ah11011793213130 01-17-93 21:31:30
12 ah11011893194116 01-18-93 19:41:16
13 ah11011993192937 01-19-93 19:29:37
14 ah11011993210718 01-19-93 21:07:18
15 ah11011993225000 01-19-93 22:50:00
16 ah11012093191829 01-20-93 19:18:29
17 ah11012093205529 01-20-93 20:55:29
18 ah11012093223715 01-20-93 22:37:15
19 ah11011093225835 01-10-93 22:58:35
20 ah11012193222446 01-21-93 22:24:46
2 1 ah11021793215909 02-17-93 21:59:09
2 ah11021893200731 02-18-93 20:07:31
3 ah11021893214700 02-18-93 21:47:00
4 ah11021993213436 02-19-93 21:34:36
5 ah11022093212229 02-20-93 21:22:29
6 ah11022393204632 02-23-93 20:46:32
7 ah11022493203445 02-24-93 20:34:45
8 ah11022193225305 02-21-93 22:53:05
9 ah11021293211842 02-12-93 21:18:42
10 ah11021393224901 02-13-93 22:49:01
11 ah11022493221524 02-24-93 22:15:24
12 ah11022593202300 02-25-93 20:23:00
13 ah11022593220258 02-25-93 22:02:58
3 2 ah11030693234025 03-06-93 23:40:25
3 ah11030593220645 03-05-93 22:06:45
4 ah11030693215435 03-06-93 21:54:35
5 ah11030693201501 03-06-93 20:15:01
6 ah11030793232649 03-07-93 23:26:49
7 ah11030793214226 03-07-93 21:42:26
8 ah11030793200318 03-07-93 20:03:18
9 ah11030893231346 03-08-93 23:13:46
10 ah11030893213003 03-08-93 21:30:03
12 ah11030993230058 03-09-93 23:00:58
13 ah11030993211757 03-09-93 21:17:57
14 ah11031093224813 03-10-93 22:48:13
15 ah11031093210608 03-10-93 21:06:08
16 ah11031193223528 03-11-93 22:35:28
17 ah11031193205404 03-11-93 20:54:04
101 ah11031293222300 03-12-93 22:23:00
102 ah11031293204217 03-12-93 20:42:17
103 ah11031393221048 03-13-93 22:10:48
104 ah11031493201831 03-14-93 20:18:31
105 ah11031493215823 03-14-93 21:58:23
106 ah11031593233054 03-15-93 23:30:54
107 ah11031593214613 03-15-93 21:46:13
108 ah11031593200703 03-15-93 20:07:03
109 ah11031693231750 03-16-93 23:17:50
110 ah11031693213350 03-16-93 21:33:50
111 ah11031693195521 03-16-93 19:55:21
112 ah11031793230447 03-17-93 23:04:47
113 ah11031793212143 03-17-93 21:21:43
114 ah11031893225201 03-18-93 22:52:01
115 ah11031893210954 03-18-93 21:09:54
116 ah11031893193217 03-18-93 19:32:17
4 1 ah11031993223932 03-19-93 22:39:32
2 ah11032093222703 03-20-93 22:27:03
3 ah11032193221436 03-21-93 22:14:36
4 ah11032293220210 03-22-93 22:02:10
5 ah11032393215001 03-23-93 21:50:01
6 ah11032493213737 03-24-93 21:37:37
7 ah11032493232140 03-24-93 23:21:40
8 ah11032593230852 03-25-93 23:08:52
9 ah11032593212530 03-25-93 21:25:30
10 ah11032093204548 03-20-93 20:45:48
11 ah11032193203401 03-21-93 20:34:01
12 ah11032293202217 03-22-93 20:22:17
101 ah11032693225605 03-26-93 22:56:05
102 ah11032693211326 03-26-93 21:13:26
103 ah11032793224320 03-27-93 22:43:20
104 ah11032793210136 03-27-93 21:01:36
105 ah11032893223052 03-28-93 22:30:52
106 ah11032693193601 03-26-93 19:36:01
107 ah11032993221824 03-29-93 22:18:24
108 ah11032993203747 03-29-93 20:37:47
109 ah11033093220558 03-30-93 22:05:58
110 ah11033093202602 03-30-93 20:26:02
111 ah11033193215348 03-31-93 21:53:48
112 ah11033193201418 03-31-93 20:14:18
113 ah11040193232544 04-01-93 23:25:44
114 ah11040193214125 04-01-93 21:41:25
115 ah11040193200236 04-01-93 20:02:36
5 1 ah11040293212917 04-02-93 21:29:17
3 ah11040393211712 04-03-93 21:17:12
4 ah11040493210523 04-04-93 21:05:23
5 ah11040493224709 04-04-93 22:47:09
6 ah11040593223305 04-05-93 22:33:05
7 ah11040593205132 04-05-93 20:51:32
11 ah11040893201604 04-08-93 20:16:04
13 ah11040793220802 04-07-93 22:08:02
14 ah11040793202752 04-07-93 20:27:52
101 ah11040993214320 04-09-93 21:43:20
102 ah11041093231503 04-10-93 23:15:03
103 ah11041093213108 04-10-93 21:31:08
104 ah11041193230156 04-11-93 23:01:56
105 ah11041193211858 04-11-93 21:18:58
106 ah11041293224920 04-12-93 22:49:20
107 ah11041293210704 04-12-93 21:07:04
108 ah11041393223632 04-13-93 22:36:32
109 ah11041393205457 04-13-93 20:54:57
110 ah11041493222359 04-14-93 22:23:59
111 ah11041493204306 04-14-93 20:43:06
112 ah11041593221128 04-15-93 22:11:28
6 1 ah11041693215858 04-16-93 21:58:58
3 ah11041793214645 04-17-93 21:46:45
4 ah11041893231829 04-18-93 23:18:29
5 ah11041893213432 04-18-93 21:34:32
6 ah11041893195609 04-18-93 19:56:09
7 ah11041993230536 04-19-93 23:05:36
8 ah11041993212221 04-19-93 21:22:21
9 ah11041993194440 04-19-93 19:44:40
10 ah11042093225247 04-20-93 22:52:47
11 ah11042193223958 04-21-93 22:39:58
12 ah11042093211014 04-20-93 21:10:14
13 ah11042193205821 04-21-93 20:58:21
14 ah11042293204629 04-22-93 20:46:29
102 ah11042493220238 04-24-93 22:02:38
104 ah11042593215010 04-25-93 21:50:10
107 ah11042793194749 04-27-93 19:47:49
108 ah11042793230904 04-27-93 23:09:04
109 ah11042793212547 04-27-93 21:25:47
110 ah11042893225613 04-28-93 22:56:13
111 ah11042893211337 04-28-93 21:13:37
112 ah11042993210144 04-29-93 21:01:44
113 ah11042993224338 04-29-93 22:43:38
114 ah11042693232211 04-26-93 23:22:11
115 ah11042593233520 04-25-93 23:35:20
7 1 ah11043093204952 04-30-93 20:49:52
2 ah11050193221834 05-01-93 22:18:34
3 ah11050193203747 05-01-93 20:37:47
4 ah11050293235244 05-02-93 23:52:44
5 ah11050293220603 05-02-93 22:06:03
6 ah11050393215335 05-03-93 21:53:35
7 ah11050393201426 05-03-93 20:14:26
8 ah11050493214119 05-04-93 21:41:19
9 ah11050493232535 05-04-93 23:25:35
10 ah11050593212907 05-05-93 21:29:07
11 ah11050693211657 05-06-93 21:16:57
12 ah11050693225949 05-06-93 22:59:49
13 ah11050293202558 05-02-93 20:25:58
101 ah11050793224659 05-07-93 22:46:59
103 ah11051093202914 05-10-93 20:29:14
104 ah11051093220921 05-10-93 22:09:21
105 ah11051193201725 05-11-93 20:17:25
106 ah11050793210449 05-07-93 21:04:49
107 ah11050993204014 05-09-93 20:40:14
108 ah11051193215651 05-11-93 21:56:51
109 ah11051193234236 05-11-93 23:42:36
110 ah11051293214437 05-12-93 21:44:37
111 ah11051293232910 05-12-93 23:29:10
112 ah11051393231601 05-13-93 23:16:01
113 ah11051393213225 05-13-93 21:32:25
8 1 ah11051493230308 05-14-93 23:03:08
2 ah11051493212013 05-14-93 21:20:13
3 ah11051493194238 05-14-93 19:42:38
4 ah11051593225017 05-15-93 22:50:17
5 ah11051593210819 05-15-93 21:08:19
6 ah11051693224235 05-16-93 22:42:35
7 ah11051693205610 05-16-93 20:56:10
8 ah11051793222509 05-17-93 22:25:09
9 ah11051793204418 05-17-93 20:44:18
10 ah11051893221241 05-18-93 22:12:41
11 ah11051893203231 05-18-93 20:32:31
12 ah11051993220010 05-19-93 22:00:10
13 ah11052093214757 05-20-93 21:47:57
14 ah11052093233247 05-20-93 23:32:47
101 ah11052193231937 05-21-93 23:19:37
102 ah11052193213544 05-21-93 21:35:44
103 ah11052293230630 05-22-93 23:06:30
104 ah11052293212333 05-22-93 21:23:33
106 ah11052393225338 05-23-93 22:53:38
107 ah11052493224103 05-24-93 22:41:03
108 ah11052593222829 05-25-93 22:28:29
109 ah11052593204736 05-25-93 20:47:36
110 ah11052693221557 05-26-93 22:15:57
111 ah11052693203545 05-26-93 20:35:45
112 ah11052793220341 05-27-93 22:03:41
113 ah11052793202355 05-27-93 20:23:55
9 2 ah11052893215111 05-28-93 21:51:11
3 ah11052993200035 05-29-93 20:00:35
4 ah11052993213857 05-29-93 21:38:57
5 ah11052993232253 05-29-93 23:22:53
6 ah11053193211450 05-31-93 21:14:50
9 ah11053093230959 05-30-93 23:09:59
10 ah11060193224416 06-01-93 22:44:16
12 ah11060293223145 06-02-93 22:31:45
13 ah11053093194905 05-30-93 19:49:05
14 ah11060393203858 06-03-93 20:38:58
15 ah11060393221912 06-03-93 22:19:12
103 ah11060593215425 06-05-93 21:54:25
105 ah11060793231315 06-07-93 23:13:15
106 ah11060793195202 06-07-93 19:52:02
107 ah11060893230026 06-08-93 23:00:26
109 ah11060693214212 06-06-93 21:42:12
110 ah11060893211752 06-08-93 21:17:52
111 ah11060793212959 06-07-93 21:29:59
112 ah11060993224751 06-09-93 22:47:51
113 ah11061093223502 06-10-93 22:35:02
114 ah11061093205405 06-10-93 20:54:05
10 1 ah11061193222229 06-11-93 22:22:29
2 ah11061193204213 06-11-93 20:42:13
3 ah11061293235637 06-12-93 23:56:37
4 ah11061293221013 06-12-93 22:10:13
5 ah11061293203023 06-12-93 20:30:23
6 ah11061393234254 06-13-93 23:42:54
7 ah11061393215743 06-13-93 21:57:43
8 ah11061393201835 06-13-93 20:18:35
9 ah11061493232940 06-14-93 23:29:40
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2 ah11111293225525 11-12-93 22:55:25
3 ah11111493205043 11-14-93 20:50:43
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22 ah11112493235243 11-24-93 23:52:43
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24 ah11112593233944 11-25-93 23:39:44
21 101 ah11121093235834 12-10-93 23:58:34
102 ah11121093221401 12-10-93 22:14:01
103 ah11121193220145 12-11-93 22:01:45
104 ah11121293233225 12-12-93 23:32:25
105 ah11121293214931 12-12-93 21:49:31
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107 ah11121493230652 12-14-93 23:06:52
108 ah11121593211324 12-15-93 21:13:24
109 ah11121593225414 12-15-93 22:54:14
110 ah11121693224203 12-16-93 22:42:03
111 ah11121693210130 12-16-93 21:01:30
113 ah11121793222904 12-17-93 22:29:04
114 ah11121893221647 12-18-93 22:16:47
115 ah11121993234807 12-19-93 23:48:07
116 ah11121993220430 12-19-93 22:04:30
117 ah11122093233511 12-20-93 23:35:11
118 ah11122193232216 12-21-93 23:22:16
119 ah11122193214017 12-21-93 21:40:17
120 ah11122293230937 12-22-93 23:09:37
121 ah11122393211608 12-23-93 21:16:08
122 ah11122393225659 12-23-93 22:56:59

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