Current research

  • Assimilation of aerosols in the GEOS-5 model: development and evaluation of an Ensemble Kalman Filter-based (EnKF) scheme to assimilate lidar information jointly with Aerosol Optical Depth (AOD) from various sensors (MODIS, MISR, ...) in GEOS-5.
    CO-I of a funded research proposal (2014-2016): Assimilating CALIOP Observation in GEOS-5 for Improving Integrated Earth System Analysis (IESA): Application to Aerosol Forcing of Climate led by Arlindo da Silva, NASA ROSES 12 - CloudSat and CALIPSO Science Team Recompete.

  • Evaluation of NASA GEOS-5 aerosols simulations:
    - Evaluation of GMAO latest reanalysis, MERRA-2 aerosol system: absorption, vertical structure, surface PM2.5, and also during several major aerosol events and field campaigns.
    - Evaluation of Version 1 of the MERRA Aerosol Reanalysis (MERRAero): AOD, absorption, vertical structure, surface PM2.5.
    These studies include the use of various observational data (OMI, MODIS, MISR, CALIOP, HSRL, AERONET, EPA, IMPROVE) to evaluate GEOS-5 aerosol data. Part of this work was also to develop a Radiative Transfer interface (VLIDORT) to retrieve Top of the Atmosphere radiances and the Aerosol Index (AI) from aerosol simulations conducted with the Goddard Chemistry, Aerosol, Radiation, and Transport (GOCART) module running on-line the GEOS-5 Atmospheric GCM. The purpose of this work is to use the AI derived from OMI measurements as independent validation for the Aerosol Reanalysis.

Ph.D. research

  • Validation of OMI/AURA data products (ozone, UV irradiance, aerosol optical depth and single scattering albedo).
  • Analysis of OMI aerosols retrievals in Western-Africa region during the AMMA campaign.
  • Development of algorithms to retrieve aerosols properties (optical thickness and single scattering albedo) from ground-based UV spectroradiometer measurements and validation with AERONET data products.
  • Radiative transfer in the atmosphere.


Colarco, P. R., Gasso', S., Ahn, C., Buchard, V., da Silva, A. M., and Torres, O.: Simulation of the Ozone Monitoring Instrument Aerosol Index using the NASA Goddard Earth Observing System Aerosol Reanalysis Products, Atmos. Meas. Tech. Discuss., doi:10.5194/amt-2017-87, (in review), 2017.

Buchard, V., C. A. Randles, A. da Silva, A. S. Darmenov, P. R. Colarco, R. C. Govindaraju, R. A. Ferrare, J. W. Hair, A. Beyersdorf, L. D. Ziemba, and H. Yu. The MERRA-2 Aerosol Reanalysis, 1980-onward, Part II: Evaluation and Case Studies. Journal of Climate, accepted, 2017.

Randles, C. A., A. da Silva, V. Buchard, P. R. Colarco, A. S. Darmenov, R. C. Govindaraju, A. Smirnov, R. A. Ferrare, J. W. Hair, Y.Shinozuka, and C. Flynn. The MERRA-2 Aerosol Reanalysis, 1980-onward, Part I: System Description and Data Assimilation Evaluation. Journal of Climate, accepted, 2017.

Gelaro, R., W. McCarty, M. J. Suarez, R. Todling, A. M. Molod, L. L. Takacs, C. Randles, A. Darmenov, M. G. Bosilovich, R. H. Reichle, K. Wargan, L. Coy, R. I. Cullather, S. R. Akella, V. Buchard, A. L. Conaty, A. da Silva, W. Gu, R. D. Koster, R. A. Lucchesi, D. Merkova, G. S. Partyka, S. Pawson, W. M. Putman, M. M Rienecker, S. D. Schubert, M. E. Sienkiewicz, and B. Zhao. The Modern-Era Retrospective Analysis for Research and Applications, Version-2 (MERRA-2). Journal of Climate, accepted, 2017.

Provencal, S., V. Buchard, A. M. da Silva, R. Leduc, and N. Barrette. Evaluation of PM2.5 surface concentration simulated by Version 1 of the NASAs MERRA Aerosol Reanalysis over Israel and Taiwan. Aerosol Air Qual. Res, (in press), 2016.

Provencal, S., V. Buchard, A. da Silva, R. Leduc, and N. Barrette. Evaluation of PM surface concentration simulated by Version 1 of the NASA MERRA Aerosol Reanalysis over Europe. Atmos. Pollut. Res, (in press), 2016.

Whiteman, D. N., Perez-Ramirez, D., Veselovskii, I., Colarco, P., and Buchard, V.. Simulations of spaceborne multiwavelength lidar measurements and retrievals of aerosol microphysics. Atmos. Meas. Tech. Discuss., doi:10.5194/amt-2016-174, (in review), 2016.

Hammer, M. S., Martin, R. V., van Donkelaar, A., Buchard V., Torres, O., Ridley, D. A., and Spurr, R. J. D. Interpreting the Ultraviolet Aerosol Index observed with the OMI satellite instrument to understand absorption by organic aerosols: implications for atmospheric oxidation and direct radiative effects. Atmos. Chem. Phys., 16, 2507-2523, doi:10.5194/acp-16-2507-2016, 2016.

Buchard V., A.M. da Silva, C.A. Randles, P. Colarco, R. Ferrare, J. Hair, C. Hostetler, J. Tackett and D. Winker. Evaluation of the surface PM2.5 in Version 1 of the NASA MERRA Aerosol Reanalysis over the United States. Atmospheric Environment, doi:10.1016/j.atmosenv.2015.11.004, 2015.

Buchard V., A. M. da Silva, P. R. Colarco, A. Darmenov, C. A. Randles, R. Govindaraju, O. Torres, J. Campbell, and R. Spurr. Using the OMI Aerosol Index and Absorption Aerosol Optical Depth to evaluate the NASA MERRA Aerosol Reanalysis. Atmos. Chem. Phys., 15, 5743-5760, doi:10.5194/acp-15-5743-2015, 2015.

Buchard V., A. da Silva, P. Colarco, N. Krotkov, R. R. Dickerson, J. W. Stehr, G. Mount, E. Spinei, H. L. Arkinson, and H. He. Evaluation of GEOS-5 sulfur dioxide simulations during the Frostburg, MD 2010 field campaign. Atmos. Chem. and Phys., 14, p 1929-1941, doi: 10.5194/acp-14-1929-2014, 2014.

Buchard V., C. Brogniez, F. Auriol, B. Bonnel. Aerosol Single Scattering Albedo retrieved from ground-based measurements in the UV and visible region. Atmos. Meas. Tech. , 4, p 1-7, doi:10.5194/amt-4-1-2011, 2011.

Ialongo I., V. Buchard, C. Brogniez, G.R. Casale and A.M. Siani. Aerosol Single Scattering Albedo retrieval in the UV range : an application to OMI satellite validation. Atmos. Chem. and Phys., 10, p 331-340, doi:10.5194/acp-10-331-2010, 2010.

Arola, A., co-authors, V. Buchard. A new approach to correct for absorbing aerosols in OMI UV. Geophys. Res. Lett., 36, L22805, doi:10.1029/2009GL041137, 2009.

Buchard V., C. Brogniez, F. Auriol, B. Bonnel, J. Lenoble, A. Tanskanen, B. Bojkov and P. Veefkind. Comparison of OMI ozone and UV irradiance data with ground-based measurements at two French sites. Atmos Chem and Phys, 8, p 4517-4528, doi:10.5194/acp-8-4517-2008, 2008.

Brogniez C., V. Buchard, and F. Auriol. Validation of UV-visible aerosol optical thickness retrieved from spectroradiometer measurements. Atmos Chem and Phys, 8, p 4655-4663, doi:10.5194/acp-8-4655-2008, 2008.

Lenoble J., C. Brogniez, A. de La Casinière, T. Cabot, V. Buchard,, and F. Guirado, 2008 : Measurements of UV Aerosol Optical Depth in the French Southern Alps. Atmos Chem and Phys , 8, p 6597-6602, doi:10.5194/acp-8-6597-2008, 2008.

Biémont E., V. Buchard, H.P. Garnir, P.H. Lefèbvre, and P. Quinet. Radiative lifetime and oscillator strength determinations in XE VI. The European Physical Journal D, 33, 181-191, doi: 10.1140/epjd/e2005-00059-y, 2005.

  • Other publications :

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

C. A. Randles, A. M. da Silva, V. Buchard, A. Darmenov, P. R. Colarco, V. Aquila, H. Bian, E. P. Nowottnick, X. Pan, A. Smirnov, H. Yu, and R. Govindaraju. The MERRA-2 Aerosol Assimilation, Technical Report Series on Global Modeling and Data Assimilation, Volume 45, NASA/TM–2016-104606/Vol. 45, 2016.

About Me

  • Employment :

01/2012-present: Research Scientist 2, NASA-GSFC GMAO / University Space Research Association, MD, USA.

05/2011-01/2012: Post-doctoral Research Associate, NASA-GSFC GMAO / University Space Research Association, MD, USA.

01/2010-05/2011: Post-doctoral Research Associate, NASA-GSFC GMAO & University of Maryland Baltimore County, MD, USA.

  • Awards :
    2016 : NASA GMAO Award for Scientific Achievement (Global Modeling and Assimilation Office)

  • Degrees :

Ph.D. thesis in Atmospheric Physics at the Laboratoire d'Optique Atmosphérique (LOA), University of Lille1, France, June 2009.
Characterization of the atmospheric contents out of ozone and aerosols using spectral measurements in UV. Validation of the OMI/AURA data products under the direction of Pr Colette Brogniez and Dr Isabelle Chiapello.

Master Degree in Physics (Optics, Molecular and Atmospheric Physics), University of Lille1, France, June 2005.
Post-graduate topic at the LOA : Ultraviolet solar radiation : measurements and modelling of the NO2 photolysis frequencies. Supervisor : Pr. Colette Brogniez

Participation to Les Houches International Summer School in Advanced Data Assimilation for Geosciences (May-June 2012).

  • Computer Skills :
    Scientific programmation/softwares : Linux, Fortran (77, 90), Python, GrADS, PyGrADS.

Actual position :
Research Scientist (GESTAR/USRA) at NASA Goddard Space Flight Center, Global Modeling Assimilation Office (GMAO).


NASA GSFC - GMAO Code 610.1
Blg 33, #C222
Greenbelt, MD, 20771, USA
tel: (+1) 301-614-6266