The Global Modeling and Assimilation Office (GMAO) is pleased to add two new products to its extensive suite of MERRA data: a new ocean surface diagnostics product, tavg1_2d_ocn_Nx (MAT1NXOCN, MATM1NXOCN and MATUNXOCN) and a new land surface diagnostics product, tavg1_2d_mld_Nx (MST1NXMLD, MSTMNXMLD and MSTUNXMLD).
MERRA Ocean Surface Diagnostics Product Release
The new ocean surface product, available at the beginning of the year, is a 1-hourly, 2-dimensional ocean surface diagnostics product on a 2/3° x 1/2° grid. Figure 1 displays images of some of the new product variables. The product is also available as a monthly mean and seasonal product. The data can be accessed through the download and visualization services provided at the GES DISC by going to:
Figure 1. Sample images generated using the MERRA Giovanni Monthly 2D instance for the flux parameters in October 2002. Click for larger image.
MERRA-Land Surface Diagnostics Product Release
A supplemental and improved set of land surface hydrological fields (“MERRA-Land”) was generated by re-running a revised version of the land component of the MERRA system (Reichle, 2012). Specifically, the MERRA-Land estimates benefit from corrections to the precipitation forcing with the global gauge-based NOAA Climate Prediction Center “Unified” (CPCU) precipitation product and from revised parameter values in the rainfall interception model, changes that effectively correct for known limitations in the MERRA surface meteorological forcings. With a few exceptions, the MERRA-Land data appear more accurate than the original MERRA estimates and are thus recommended for those interested in using MERRA output for land surface hydrological studies.
As an example, Figure 2 examines the drought conditions experienced across the western United States and along the East Coast during August 2002. The MERRA and MERRA-Land drought indicator shown in the figure is derived by ranking, separately for each grid cell, the normalized, monthly mean root zone soil moisture anomalies for June, July, and August of 1980 through 2011 and converting the rank for August 2002 into percentile units. For comparison, the drought severity assessed independently by U.S. Drought Monitor is also shown. The figure clearly demonstrates that MERRA-Land data are more consistent with the Drought Monitor than MERRA data.
The data can be accessed through the download and visualization services provided at the GES DISC by going to:
MERRA-land 2d land surface diagnostics, time averaged, single level, at native resolution
Figure 2. Comparison of original and updated MERRA land surface products, with the U.S. Drought Monitor assessment for the same period of August 2002. Click for poster-size image.
Reichle, R. H. and Coauthors (2011b), GMAO Research Highlights: The MERRA-Land data product, available at
MERRA is a project of the NASA Goddard Space Flight Center Global Modeling and Assimilation Office (GMAO). MERRA is funded by the NASA Modeling Analysis and Prediction (MAP) program.
The GES DISC is a NASA earth science data center, part of the NASA Earth Science Data and Information System (ESDIS) Project.
Text and figures provided by the GMAO and Dana Ostrenga, NASA GES DISC. Editing by James Acker.
Questions or comments? Email the NASA GES DISC Help Desk, email@example.com