Summary

Description

The reprocessed Version-3 Aura OMI Level-2G Cloud data product OMCLDRRG has been made available (in April 2012) to the public from the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC).(http://disc.gsfc.nasa.gov/Aura/OMI/omcldrrg_v003.shtml Aura OMI provides two Level-2G Cloud products (OMCLDRRG and OMCLDO2G)that are based on two different algorithms, the Rotational Raman Scattering method and the O2-O2 absorption method. This level-2G global cloud product (OMCLDRRG) provides effective cloud pressure and effective cloud fraction that is based on the least square fitting of the Ring spectrum (filling-in of Fraunhofer lines in the range 392 to 398 nm due to rotational Raman scattering). This product also contains many ancillary and derived parameters, terrain and geolocation information, solar and satellite viewing angles, and quality flags. (The shortname for this Level-2G OMI Cloud Pressure and Fraction product is OMCLDRRG) The algorithm lead for the products OMCLDRR and OMCLDRRG is NASA OMI scientist Dr. Joanna Joinner(Joanna.Joiner.1 at nasa.gov ). OMCLDRRG data product is a special Level-2G Gridded Global Product where pixel level data (OMCLDRR)are binned into 0.25x0.25 degree global grids. It contains the OMCLDRR data for all L2 scenes that have observation time betweeen UTC times of 00:00:00 and 23:59:59.9999. All data pixels that fall in a grid box are saved Without Averaging. Scientist can apply data filtering scheme of their choice and create new gridded products. OMCLDRRG data products are stored in EOS Hierarchical Data Format (HDF-EOS5). Each daily file contains data from the day lit portion of the orbits (~14 orbits). The average file size for the OMCLDRRG data product is about 75 Mbytes. A list of tools for browsing and extracting data from these files can be found at: http://daac.gsfc.nasa.gov/Aura/tools.shtml. The GES DISC developed interactive tool Giovanni ( http://giovanni.gsfc.nasa.gov/ ) provides on-line web based capabilities to browse and explore Aura data. A README document containing brief algorithm description and known data quality related issues and file spec are provided by the OMCLDRR and OMCLDRRG Algorithm lead (see http://disc.sci.gsfc.nasa.gov/Aura/OMI/omcldrrg_v003.shtml ). Data Category Parameters: The OMCLDRRG data file consists of a Grid Data Object which contains complete information of each pixel binned into the grid. Cloud Parameters (and Precision): Two Effective Cloud Fraction and Cloud Pressure (based on two different clear and cloudy scene reflectivity criteria), Cloud Mask Ancillary Data: Terrain Pressure, Terrain Height, Reflectivity, Chlorophyll Amount, Effective Reflectivity (394.1 micron), UV Aerosol Index (based on 360 and 388 nm), and many other Algorithm Parameters Quality Flags: Ground Pixel QualityFlags, Measurement QualityFlags, Processing Quality Flags Time and Geolocation Data: Time, Latitude, Longitude, Solar Zenith Angle, Viewing Zenith Angle, Relative Azimuth Angle, Line Number, Scene Number, Number Of Candidate Scenes, Path Length, Orbit Number