The MAC0NXASM or const_2d_asm_Nx data product is the MERRA Data Assimilation System 2-Dimensional Constants at native resolution. MERRA, or the Modern Era Retrospective-analysis for Research and Application, is a NASA reanalysis for the satellite era (30 years 1979-current) using the Goddard Earth Observing System Data Assimilation System Version 5 (GEOS-5 DAS).
... This data product contains 2-dimensional fields that do not vary during the reanalysis. Parameters include:
PHIS - surface geopotential height (m2/s2) SGH - standard deviation of topography for gravity wave drag (m) FRLAKE - fraction of lake type in grid box (fraction) FRLAND - fraction of land type in grid box (fraction) FRLANDICE - fraction of land ice type in grid box (fraction) FROCEAN - fraction of ocean in grid box (fraction) AREA - horizontal area of grid box (m2)
The data are on the GEOS-5 native 540 x 361 grid with 2/3° longitude x 1/2° latitude resolution. File sizes are about 5.5 Mbytes. Data are archived in the HDF-EOS (Grid) format, based on HDF4.
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