Summary of ADAPS 1KM Benchmark

Verification of calibration code

General Notes

All images are windowed to be 874 samples on each side of nadar (1748 samples total, this is what is done in production). Consequently, 150 samples on the extreme left and right are dropped.

The actual data is not used for the image, but rather a computed image wedge of data with values ranging from 0 - 1023 (range of valid raw AVHRR data for all five bands). None-the-less, windows with data ideal for an atmospheric correction test have been selected, and this actual image data is saved, though not used for now.

Criteria for testing

Test case scenarios

Test case scenario #1
Original image name
ah11062094213142 from archive tape 064038.
Windowing of image
512 lines close to 40 degrees latitude were selected. So the window is (2880,151,512,1748) for all 5 bands.
Rational of test scenario
This image was chosen because it is approx. at summer solstice (extreme solar angles), is an ascending pass over the US at approx. 40 deg latitude. Optical calibration degradation file being used is "PRELAUNCH". The test is run with illumination correction applied (reflectance output values) and without illumination correction applied (radiance output values).
Test case scenario #2
Original image name
ah11092990203303 from archive tape 053509.
Windowing of image
512 lines close to 40 degrees latitude. The window is (2200,151,512,1748) for all 5 bands. This window includes the Great Salt Lake and surrounding area.
Rational of test scenario
This image was chosen because it is approx. two years past the launch of the NOAA-11 satellite. Consequently, this is a good time frame to verify the TEILLET calibration method. It is also during the time of the fall equinox. It is an ascending pass over the US at approx. 40 deg latitude. Optical calibration degradation file being used is "TEILLET". Illumination correction is applied.
Also run a SOFTWARE test
The calibration period and number of calibration periods is varied from the default. Also, the order of bands is altered from the default to make certain the correct AVHRR channels are still processed. NOTE: The variation of CALPER and NCALS will cause differences in accuracy in the output, especially if illumination correction is being applied. The biggest differences can be seen in AVHRR band 3 right where the input signal becomes large enough to force the computed thermal value to its minimum value (160 degrees).
Test case scenario #3
Original image name
ah14012295185257 from archive tape 075414.
Windowing of image
512 lines at the northern-most part of the scene (not close to 40 degrees latitude). The window is (1,151,512,1748) for all 5 bands. This window was chosen because there are multiple dropped lines in the image window, and the available data is fairly cloud free.
Rational of test scenario
This image was chosen because it is a NOAA-14 scene with drop lines surrounded by fairly clear data. Note that this data is not near 40 deg lat but in Canada. Optical calibration degradation file being used is "PRELAUNCH". Illumination correction is being applied.
Test case scenario #4
Original image name
ah12122192131236 from archive tape 027117.
Windowing of image
512 lines at the center part of the scene (close to 40 degrees latitude). The window is (2400,151,512,1748) for all 5 bands.
Rational of test scenario
This image was chosen because it is a NOAA-12, it is a '92 scene, it is a winter solstice scene at approx. 40 degrees latitude. Optical calibration degradation file being used is "PRELAUNCH". Illumination correction is and is not being applied (two tests).

Verification of normalized difference calculation

General Notes

1KM production conditions are held constant:

Test case scenarios

Test case scenario #1

Test with an image of mask values specifying NONE and US scaling (results should be the same since neither does anything special with "mask" values).

Test case scenario #2

Run test #1 only specifying GLOBAL scaling (GLOBAL scaling does use mask values). Compare the results with predetermined answers. The mask combinations used in this test are equal.

Test case scenario #3

Repeat test #2 only in this test specify an invalid combination of mask values. Verify that a fatal error results.

Test case scenario #4

Repeat test #3 except specifying NONE and US scaling. Verify that a fatal error does NOT occur since special "mask" values do not exist for NONE and US scaling algorithms. Verify that the same answers are obtained for both scaling algorithms (US and NONE). Compare results to pre-determined answers.

Test case scenario #5

Run a test using GLOBAL scaling where both bands are equal. Compare the results to pre-determined answers.

Test case scenario #6

Run a test using NONE and US scaling where both bands are equal. Compare the results to pre-determined answers.

Test case scenario #7

Run a test where one input band has values which increment from 10 to 1023 vertically, the other input band has values which increment from 10 to 1023 in the horizontal direction. Use GLOBAL scaling. This scenario ensures the testing of all possible combinations of values except for mask values (illegal combinations of mask values would force this test to fail). Compare the results to pre-determined answers.

Test case scenario #8

Run a test where one input band has values which increment from 0 to 1023 vertically, the other input band has values which increment from 0 to 1023 in the horizontal direction. Use NONE and US scaling. This scenario ensures the testing of all possible combinations of values (there are no mask values for NONE and US scaling). Compare the results to pre-determined answers.

Verification of 1KM production flow results

General Notes

Process AVHRR scenes much like that done in production Global 1KM processing and verify the output with established results. Four test scenes have been selected:

Processing flow

The following processing flow will be performed on each test scene:

Begin by running line detection on the raw AVHRR archive image. Verify the results with pre-determined answers.

Call GACOSINFO to get the information for this study area. This information will be used throughout the remainder of the test.

Call AVHRRIN-LATRANGE to convert the AVHRR archive image to a LAS image. Only convert the data which falls within the proper latitude, longitude, and quadrant number. Only convert 874 pixels on either side of nadar (truncate extreme 150 pixels on both edges of the image).

Calibrate the data next. Call AVHRRCAL for the line detected LAS image. Specify VERMOTE tables and no illumination correction to be applied. Calibrate all 5 AVHRR bands with radiance output values, "I*2" output data type, and with GLOBAL scaling applied. Verify the results with pre-determined answers.

Call AUTONAV-MULTI to test the navigation of the scene. Several attempts will be made to navigate the image using DCW and WVS data. If the scene successfully navigates verify the results by comparing the ;addr file (only thing that changes because of navigation). If the scene does not successfully navigate, continue on.

Next reproject the image. Call PROJPRM, SWINDOW, RECTIFY, and GEOM to generate reprojected bands of AVHRR data ("I*2" data using GLOBAL scaling). Use nearest neighbor resampling. Call ANGINTERP to generate bands of sun and satellite angles in the same projection space as the AVHRR data (byte data using GLOBAL scaling). Verify the results by comparing them with pre-determined answers. The angle bands will be needed for atmospheric correction.

Call NORMD to generate normalized difference results. The results are byte data using GLOBAL scaling. A scale factor of 100 and a normalized limit of 185 is specified.

Map the solar angle band to the NDVI band as well as bands 1 and 2 of the AVHRR image. Do not use solar angles greater than 79 degrees. Verify the results by comparing them with pre-determined answers.

Prepare to atmospherically correct bands 1 and 2 of the AVHRR image. Get the appropriate elevation image, ozone image, and water mask. Apply the water mask and interrupt area mask to the AVHRR image. Call ATMOCOR to atmospherically correct the visible AVHRR bands. The output is radiance values using GLOBAL scaling. Verify the results by comparing them with pre-determined answers.

After atmospherically correcting AVHRR bands 1 and 2, recalculate the NDVI of bands 1 and 2 using the same parameters as the first time. Verify the results by comparing them with pre-determined answers.