Short Name:

MODIS/Terra Clear Radiance Statistics Indexed to Global Grid 5-Min L2 Swath 10km

The MODIS/Terra Clear Radiance Statistics Indexed to Global Grid 5-Min L2 Swath 10km (MODCSR_G) product provides a variety of statistical measures that characterize observed top-of-atmosphere clear sky radiances at a 10 km spatial resolution. Clear radiances are collected for all Earth scenes and separated by day and night. The MODCSR_G serves as input to the downstream Level 3 aggregation processes that culminate with the production of the 1-degree Zonal Bias Product (MODCSR_B) used as input to PGE06 (MODIS Cloud Product). MODCSR_G data are collected for bands 1-7 and 17-36 for all but the last two statistics. Calculated clear-sky radiances are produced for bands 20, 22-25, and 27-36 and subtracted from observed values. Differences in bands 31 and 33-36 are summed and used to create the clear-sky biases used in generating the PGE06 cloud top pressure field. Numbers of observations from land vs. water are also kept for each 25-km region. Biases are used to quantify the difference between instrument observed radiances and a calculated radiance. This difference is especially important for the cloud top properties retrieval which utilizes an atmospheric transmittance model as a means of calculating radiances in different layers of the atmosphere and matching that to observations. A granule-based forward clear sky radiance file is created prior to MODCSR_G processing. The biases contained in MODCSR_G are the differences between the calculated radiances and the observed radiances for all clear-sky grid cells which fall within the given granule. Several different ways of determining these were studied, including an attempt to interpolate observed biases across grid boxes where no clear sky scenes could be found for a given day. The MODCSR_G files are in Hierarchical Data Format (HDF).

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