Sorry, you need to enable JavaScript to visit this website.

Joint Atm Data Issues

Tracking of known problems and subsequent fixes is an important issue for MODIS data users. This page will act as a repository of all known MODIS Atmosphere Data Product problems, as well as how to determine the problematic version (and the fixed version) of the HDF data -- therefore data users should check this page for updates regularly. Data Users unfamiliar with how to properly track problems and fixes by determining the version of their downloaded HDF files should refer to the documentation at the bottom of this page.

Issue with Sampling of "potentially paired" SSH files

Description: 

For some scientific studies, some users might wish to pair SSH files with ATML2 files. MOD02SSH files contain subsampled geolocation (latitude and longitude) and solar and sensor angles from the MOD03 files, as well as subsampled Earth view radiance/reflectance and uncertainty indexes from the L1B files. Due to a coding error in the SSH code, the subsampled geolocation in the SSH (which was incorrectly specified) does not match the subsampled geolocation in the ATML2 (which was correctly specified), a problem that affects both Terra and Aqua MODIS.

The ATML2 sampling (correctly) starts at column 3, row 4 in the 1km geolocation data, but the SSH sampling (incorrectly) starts at column 4, row 3. It appears that the sampling changes that were made for C6 to align the SSH and ATML2 sampling, and to sample the working Aqua detectors, did not get applied to the SSH geolocation SDSs. Users should also note that the solar and sensor angles (zenith and azimuth) in the SSH are sampled consistent with the SSH geolocation, and are thus also incorrect.

Advice to Users: When pairing SSH and ATML2 files, users should point to (use) the ATML2 for the correct geolocation (latitude and longitude) information, and ignore or bypass the geolocation in the SSH files. However, the angle SDSs are unfortunately only available in the SSH files. Because the sampling differences are only a single pixel (1km at nadir) in the x and y horizontal directions, this disconnect is not expected to have a significant impact on results obtained by pairing these two datasets, but it does exist and introduces a discontinuity.

PGE Versions & Production Dates of Problematic & Corrected Data:

Problematic Data Corrected Data
PGE Versions Production Dates PGE Versions Production Dates
All All Not Corrected Not Corrected

Data Dates Affected: All data since launch.

Affected Platform: 
Aqua and Terra
Products Affected: 
Collections Affected: 

Note to Users: 5km Cell Across Swath Dimension change from 270 to 271

Description: 

It should be noted that in the native (input) Cloud (06_L2) and Profiles (07_L2) the 5km parameters have the dimension Cell_Across_Swath_5km = 270. This dimension was matching 270 in the C5 and C51 Joint Atmosphere L2 product.  However in the Collection 6 Joint Atmosphere L2 Product, that dimension was increased from 270 to 271 in order to match the dimension in the MOD02SSH input files, when information from that new input file was added to the Joint Atmosphere L2 product.  In this case the last element in that 271 dimension will always be fill for 5km Cloud and Profile SDS's.  This is not a bug or an error, but simply a characteristic of the C6 data, which users should note!

 

Data Dates Affected: All data since launch.

Affected Platform: 
Aqua and Terra
Products Affected: 
Collections Affected: 

Problems in input 04_L2, 05_L2, 06_L2, 07_L2, and 35_L2 propagate into downsteam products

Description: 

See the Known Problem pages for the input Level-2 products 04_L2 (Aerosol), 05_L2 (Water Vapor), 06_L2 (Cloud), 07_L2 (Profiles), and 35_L2 (Cloud Mask) by clicking on the links to the left. Any problem in these upstream products will propagate downsteam.  Users should be aware of any issues in the upstream products.

Affected Platform: 
Aqua and Terra
Products Affected: 
Collections Affected: