Modern Era Retrospective-Analysis for Research and Applications (MERRA)
This special collection of the Journal of Climate focuses on some early scientific results from the Modern-Era Retrospective analysis for Research and Applications (MERRA). MERRA is a NASA reanalysis for the satellite era (1979- present) using the Goddard Earth Observing System Atmospheric Data Assimilation System, version 5 (GEOS-5). MERRA was undertaken by NASA’s Global Modeling and Assimilation Office with the objectives of placing the observations from NASA’s Earth Observing System satellites in a climate context, and improving upon the hydrologic cycle represented in earlier generations of reanalyses.
In addition to an overview paper on the MERRA system and some aspects of its performance (Rienecker et al.), the papers in this special collection provide a broad spectrum of scientific applications of MERRA including the hydrological cycle, the climates of polar regions, African easterly waves, stratospheric/tropospheric coupling, land surface estimates, tropical cyclones, atmospheric Rossby waves and climate extremes, atmosphere/ocean fluxes, ocean biogeochemistry, and various comparisons with other reanalyses and observations. The recent availability of three new reanalyses—MERRA, CFSR and ERA-Interim, provides researchers with a de facto ensemble of state-of-the-art climate analyses for making robust quality assessments and quantifying uncertainties. This collection provides an early view of such issues in several contexts.
Dr. Siegfried Schubert, NASA/GSFC