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Randles CA, Da Silva AM, Buchard V, Colarco PR, Darmenov A, Govindaraju R, Smirnov A, Holben B, Ferrare R, Hair J, Shinozuka Y, Flynn CJ. The MERRA-2 Aerosol Reanalysis, 1980 - onward, Part I: System Description and Data Assimilation Evaluation. JOURNAL OF CLIMATE 2017; 30:6823-6850. [PMID: 29576684 PMCID: PMC5859955 DOI: 10.1175/jcli-d-16-0609.1] [Citation(s) in RCA: 199] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) updates NASA's previous satellite era (1980 - onward) reanalysis system to include additional observations and improvements to the Goddard Earth Observing System, Version 5 (GEOS-5) Earth system model. As a major step towards a full Integrated Earth Systems Analysis (IESA), in addition to meteorological observations, MERRA-2 now includes assimilation of aerosol optical depth (AOD) from various ground- and space-based remote sensing platforms. Here, in the first of a pair of studies, we document the MERRA-2 aerosol assimilation, including a description of the prognostic model (GEOS-5 coupled to the GOCART aerosol module), aerosol emissions, and the quality control of ingested observations. We provide initial validation and evaluation of the analyzed AOD fields using independent observations from ground, aircraft, and shipborne instruments. We demonstrate the positive impact of the AOD assimilation on simulated aerosols by comparing MERRA-2 aerosol fields to an identical control simulation that does not include AOD assimilation. Having shown the AOD evaluation, we take a first look at aerosol-climate interactions by examining the shortwave, clear-sky aerosol direct radiative effect. In our companion paper, we evaluate and validate available MERRA-2 aerosol properties not directly impacted by the AOD assimilation (e.g. aerosol vertical distribution and absorption). Importantly, while highlighting the skill of the MERRA-2 aerosol assimilation products, both studies point out caveats that must be considered when using this new reanalysis product for future studies of aerosols and their interactions with weather and climate.
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Affiliation(s)
- C. A. Randles
- Global Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- Corresponding author address: C. A. Randles, 1545 US-22, Clinton, NJ, 08801,
| | - A. M. Da Silva
- Global Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - V. Buchard
- Global Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- GESTAR/Universities Space Research Association, Columbia, Maryland, USA
| | - P. R. Colarco
- Atmospheric Chemistry and Dynamics Lab, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - A. Darmenov
- Global Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
| | - R. Govindaraju
- Global Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
- Science Systems and Applications, Inc., Lanham, MD, USA
| | - A. Smirnov
- Science Systems and Applications, Inc., Lanham, MD, USA
- NASA Biospheric Sciences Laboratory, Greenbelt, Maryland, USA
| | - B. Holben
- NASA Biospheric Sciences Laboratory, Greenbelt, Maryland, USA
| | - R. Ferrare
- NASA Langley Research Center, Hampton, VA, USA
| | - J. Hair
- NASA Langley Research Center, Hampton, VA, USA
| | - Y. Shinozuka
- Bay Area Environmental Research Institute, Petaluma, California, USA
- NASA Ames Research Center Cooperative for Research in Earth Science and Technology, Moffett Field, California, USA
| | - C. J. Flynn
- Pacific Northwest National Laboratory, Richland, Washington, USA
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