Sciences and Exploration Directorate

Ronald Gelaro



Org Code: 610.1

Mail Code: 610.1
Greenbelt, MD 20771

Employer: NASA

Brief Bio

Ron Gelaro is the Lead Scientist for atmospheric data assimilation at the Global Modeling and Assimilation Office at NASA Goddard Space Flight Center.  In this capacity he oversees the development of the Goddard Earth Observing System Forward Processing (GEOS-FP) system, which produces real-time weather analysis and forecast products used by NASA instrument teams and other internal and external researchers. Ron also plays a key role in the development of GMAO's climate reanalysis systems, including the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), and is a member of GMAO's senior management team.


Ron’s scientific expertise is in the areas of data assimilation and predictability as it pertains to numerical weather prediction, including the use of adjoint methods to quantify and understand the impact of observations on numerical weather forecasts. Over the years, Ron’s interests have evolved from basic and applied research in these areas toward the development of operational-quality systems for weather analysis and prediction.


Most recently, Ron leads the development of GMAO’s next-generation data assimilation system, which couples the GEOS model with the Joint Center for Satellite Data Assimilation (JCSDA) Joint Effort for Data assimilation Integration (JEDI) infrastructure. This new system will provide GMAO with a unified capability for coupled Earth system analysis and prediction of the atmosphere, ocean, land and cryosphere.


Meteorologist - AST, Atmospheric Measurements

NASA - Goddard Space Flight Center

February 2001 - Present

Research Meteorologist

US Navy - Naval Research Laboratory, Monterey CA

June 1985 - February 2001

Meteorologist - Visiting Scientist

European Center for Medium-Range Weather Forecasts (ECMWF) - Reading, England UK

1994 - 1995


1989: Ph.D. in Meteorology, The Pennsylvania State University

1983: M.S. in Meteorology, The Pennsylvania State University

1980: B.S. in Meteorology, with honors, The Pennsylvania State University


2021: Robert H. Goddard Award, for Merit

Professional Service

Ron serves as NASA's Executive Team representative for the Joint Center for Satellite Data Assimilation (JCSDA), where he helps develop and oversee the scientific program of this important inter-agency collaboration in data Earth system data assimilation. He has served on external review panels for NRL Marine Meteorology Division and the NASA Short-term Prediction Research and Transition Center (SPoRT), and has served multiple times as a member of the scientific organizing committee of the World Meteorological Organization's (WMO) Workshop on the Impact of Various Observing Systems on Numerical Weather Prediction and Earth System Prediction and other national and international meetings.



McGrath‐Spangler, E. L., M. Ganeshan, O. Reale, et al. N. Boukachaba, W. McCarty, and R. Gelaro. 2021. Sensitivity of low tropospheric Arctic temperatures to assimilation of AIRS cloud‐cleared radiances: Impact on mid‐latitude waves Quarterly Journal of the Royal Meteorological Society 147 (741): 4032-4047 [10.1002/qj.4166]

Moradi, I., K. F. Evans, W. McCarty, et al. M. Cordero-Fuentes, R. Gelaro, and R. A. Black. 2020. Assimilation of Satellite Microwave Observations over the Rainbands of Tropical Cyclones Monthly Weather Review 148 (12): 4729-4745 [10.1175/mwr-d-19-0341.1]

Kim, M.-J., J. Jin, A. El Akkraoui, et al. W. R. Mccarty, R. Todling, W. Gu, and R. Gelaro. 2020. The Framework for Assimilating All-Sky GPM Microwave Imager Brightness Temperature Data in the NASA GEOS Data Assimilation System Monthly Weather Review 148 2433-2455 [10.1175/MWR-D-19-0100.1]

Reale, O., E. L. McGrath-Spangler, W. McCarty, D. Holdaway, and R. Gelaro. 2018. Impact of adaptively thinned AIRS cloud-cleared radiances on tropical cyclone representation in a global data assimilation and forecast system Weather and Forecasting 33 (4): 908-931 [10.1175/waf-d-17-0175.1]

Gelaro, R., W. McCarty, M. J. Suárez, et al. R. Todling, A. Molod, L. Takacs, C. Randles, A. Darmenov, M. G. Bosilovich, R. Reichle, K. Wargan, L. Coy, R. Cullather, C. Draper, S. Akella, V. Buchard, A. Conaty, A. da Silva, W. Gu, G.-K. Kim, R. Koster, R. Lucchesi, D. Merkova, J. E. Nielsen, G. Partyka, S. Pawson, W. Putman, M. Rienecker, S. D. Schubert, M. Sienkiewicz, and B. Zhao. 2017. The Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) Journal of Climate 30 5419–5454 [10.1175/jcli-d-16-0758.1]

Holdaway, D., R. M. Errico, R. Gelaro, J. G. Kim, and R. B. Mahajan. 2015. A Linearized Prognostic Cloud Scheme in NASA’s Goddard Earth Observing System Data Assimilation Tools Monthly Weather Review 143 (10): 4198-4219 [10.1175/MWR-D-15-0037.1]

Holdaway, D. R., R. M. Errico, R. Gelaro, and J. G. Kim. 2014. Inclusion of Linearized Moist Physics in NASA’s Goddard Earth Observing System Data Assimilation Tools Mon. Weather Rev. 142 (1): 414-433 [10.1175/MWR-D-13-00193.1]


Errico, R. M., N. C. Prive, D. Carvalho, et al. M. E. Sienkiewicz, A. El Akkraoui, J. Guo, R. Todling, W. R. Mccarty, W. M. Putman, A. M. Da Silva, R. Gelaro, and I. Moradi. 2017. Description of the GMAO OSSE for Weather Analysis Software Package: Version 3 NASA Technical Report Series on Global Modeling and Data Assimilation, NASA/TM-2017-104606 48 156 pp.

Mccarty, W. R., L. Coy, R. Gelaro, et al. A. Huang, D. Merkova, E. B. Smith, M. E. Sienkiewicz, and K. Wargan. 2016. MERRA-2 Input Observations: Summary and Assessment Technical Report Series on Global Modeling and Data Assimilation 46 (NASA/TM–2016-104606):

Bosilovich, M. G., S. R. Akella, L. Coy, et al. R. I. Cullather, C. S. Draper, R. Gelaro, R. M. Kovach, Q. Liu, A. M. Molod, P. M. Norris, K. Wargan, C. Yang, R. H. Reichle, L. L. Takacs, Y. V. Vikhliaev, S. C. Bloom, A. Collow, S. Firth, G. J. Labow, G. S. Partyka, S. Pawson, O. Reale, S. D. Schubert, and M. J. Suarez. 2015. MERRA-2: Initial Evaluation of the Climate NASA Technical Report Series on Global Modeling and Data Assimilation 43 (NASA/TM–2015–10) 139 pp.

Gelaro, R., W. M. Putman, S. Pawson, et al. C. S. Draper, A. M. Molod, P. M. Norris, L. E. Ott, N. C. Privé, O. Reale, D. Achuthavarier, M. G. Bosilovich, V. J. Buchard, W. C. Chao, L. Coy, R. I. Cullather, A. M. Da Silva, A. S. Darmenov, R. M. Errico, M. Fuentes, M.-J. Kim, R. D. Koster, W. R. Mccarty, J. Nattala, G. S. Partyka, S. D. Schubert, G. R. Vernieres, Y. V. Vikhliaev, and K. Wargan. 2015. Evaluation of the 7-km GEOS-5 Nature Run NASA Technical Report Series on Global Modeling and Data Assimilation 36 (NASA/TM-2014-104606):