MODIS/Terra Near Real Time (NRT) Level 1B Subsampled Calibrated Radiance 5Km (MOD02SSH, Collection 004 and 005)Entry ID: MOD02SSH
Abstract: This Near Real Time (NRT) data type (MOD02SSH) is a subsample from the MODIS Level 1B 1-km data. Every fifth pixel is taken from the MOD021KM product and written out to MOD02SSH. The subsampling starts at the third frame, and at the third line. Here, "frame" and "line" are naming conventions for pixels along and across the ... scan, respectively. Since MOD02SSH is a subsampled Level 1B , many things from the Level 1B documentation apply as well. That is, the MOD02SSH data product contains calibrated and geolocated at-aperture radiances for 36 bands generated from MODIS Level 1A scans of raw radiance (MOD 01). The radiance units are in W/(m ^2 um sr). Additional data are provided including quality flags, error estimates and calibration data. Visible, shortwave infrared (SWIR), and Near Infrared (NIR) measurements are made during daytime only, while radiances for Thermal Infrared (TIR) are measured continuously. As it's parent, the MOD02SSH is in HDF-EOS format, and all metadata structures and names are preserved for better convenience. However, some relevant changes are made where appropriate. E.g. the dimension mappings are updated to reflect the new one-to-one correspondance between the data and geolocations. The latter is one of the most important differences: in the MOD02SSH, there is no offset between data and geolocation pixels. The spatial coverage is almost similar to that from MOD021KM (nominally it is 2330 by 2030 km, cross-track by along-track, respectively). The MOD02SSH is produced continuously, and thus the processing provides 2-day repeat observations of the Earth with a repeat orbit pattern every 16 days. (The shortname for this product is MOD02SSH) The V004 Program Executable (PGE), for MODIS Level 1B products, has gone through a series of revisions since the initial release of V4.0.0 in March of 2002. These include revisions to make it LINUX-compatible. The current version is V4.0.9, which does not contain changes to the code that affect scientific output. Below is a brief overview of changes that affect scientific output in previous versions (V4.0.0 to V4.0.7) of PGE code. The MCST web site, listed in the URL section of this DIF, has a more detailed version of this information, including revisions that do not affect scientific output. Significant changes to Look Up Tables (LUT) used in Level 1B processing have occurred. These include revising the Response-versus-Scan Angle (RVS) LUTs from listing the RVS corrections to listing the quadratic coefficients used in making the RVS correction. The coefficients are now calculated by interpolating on the granule collection time and the RVS corrections are then generated using the interpolated coefficients. Previously used Emissive and Reflective RVS LUT tables were eliminated and new ones introduced. An incorrect comparison between RVS coefficients for Thermal Emissivity Bands (TEB) and Reflective Solar Bands (RSB) was being made during the calculation of the RVS coefficients. This was replaced with a comparison between TEB coefficients. This error never resulted in an incorrect RVS correction but did lead to re-calculating the coefficients for each detector in a thermal band even if the coefficients were the same for all 10 detectors. A destriping algorithm for Band 26 devised by C. Moeller was implemented. A new time-dependent LUT was added which gives coefficients for a detector-specific cross-talk correction based on the aggregated Band 5 radiances. The Band 26 scaled integers are adjusted by the Band 5 correction term, which is the product of the Band 5 radiance times the ratio of the Band 5 to Band 26 scaling factors times the LUT correction value for that detector. In addition a new LUT which allows for a frame offset with regard to the Band 5 radiance was added. A LUT which switches the correction off or on was also added. See the homepage for more data set information: http://modis.gsfc.nasa.gov/data/dataprod/
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Data Set Citation
Start Date: 2015-12-31
Temporal Resolution: Two day repeat observations with a repeat orbit pattern every 16 days.
Quality Overall NRT products match to operational with some expected minor differences from use of different ancillaries and ephemeris. There aren't any data gaps or data artifacts. Information on comparison of C5 Operational and NRT Atmospheric Products is posted at: http://lance.modaps.eosdis.nasa.gov/data_products/comparison.html. Information on comparison of C6 Operational and NRT Atmospheric and Land Products is posted at: http://lance3.modaps.eosdis.nasa.gov/data_products/comparison_atmos... and http://lance3.modaps.eosdis.nasa.gov/data_products/comparison_land.....
Use Constraints None. See disclaimer: https://earthdata.nasa.gov/data/near-real-time-data/about-lance/dis....
Data Set Progress
Extended Metadata Properties
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