Sciences and Exploration Directorate

Research Interests


Data Assimilation for Earth System Science, Atmospheric Dynamics and Stochastics, Numerical Weather Prediction, Estimation Theory, Partial Differential Equations

Earth Science: Theory & Modeling

Positions/Employment


Research Meteorologist, Computer Scientist, Mathematician

NASA Goddard Space Flight Center - Greenbelt, Maryland

1991 - Present


Research Scientist

Universities Space Research Association - Greenbelt, Maryland

1991 - 1991


UCAR Senior Fellow

National Meteorological Center - Camp Springs, Maryland

1990 - 1991


Visiting Professor

Universidade Federal do Rio de Janeiro - Rio de Janeiro, Brazil

1988 - 1988


Visiting Professor

Universita di Catania - Catania, Italy

1987 - 1987


Visiting Professor

Pontificia Universidade Catolica do Rio de Janeiro - Rio de Janeiro, Brazil

1983 - 1985


Assistant Research Scientist through Research Assistant Professor

Courant Institute of Mathematical Sciences, New York University - New York, New York

1982 - 1991

Education


Ph.D., Mathematics, Courant Institute of Mathematical Sciences, New York University, 1982. Thesis Title: Methods of Sequential Estimation for Determining Initial Data in Numerical Weather Prediction

M.S., Mathematics, Courant Institute of Mathematical Sciences, New York University, 1978

B.S., Physics and Mathematics, Drexel University, 1976 

Professional Societies


American Meteorological Society

1978 - Present


American Mathematical Society

1976 - Present


Society for Industrial and Applied Mathematics

1976 - Present

Professional Service


2016 - 2021: Assistant Chief, Global Modeling and Assimilation Office

2014 - 2021: Member, GMAO Strategic Management Team

2008 - 2009: Member, International Scientific Organizing Committee, Fifth WMO International Symposium on Data Assimilation, Melbourne, Australia

2005: Guest Editor, Quarterly Journal of the Royal Meteorological Society

2004 - 2005: Co-Chair, International Program Committee, Fourth WMO International Symposium on Assimilation of Observations in Meteorology and Oceanography, Prague, Czech Republic

2003 - 2008: Editor, Monthly Weather Review

2002 - 2003: Member, Scientific Committee, Roger Daley Memorial Symposium, Montreal, Canada

2002: Lecturer, NATO Advanced Study Institute (ASI) on Data Assimilation for the Earth System, Maratea, Italy

2000 - 2002: Chief Scientist for Analysis, Data Assimilation Office, GSFC

2000 - 2001: Ph.D. Thesis Supervisor (Tijana Janjic), University of Maryland College Park

2000 - 2001: Special Faculty, University of Maryland College Park

1998 - 2000: Associate Editor, Monthly Weather Review

1995: Member, Scientific Committee, Second UNAM-Cray Supercomputing Conference on Numerical Simulations in the Environmental and Earth Sciences, Mexico City, Mexico

1993 - 1998: Lead Scientist for GEOS Data Assimilation System Development, GSFC

1993 - 1995: Fellow, Joint Center for Earth System Science

1992, 2002: Branch Representative, Summer Institute on Atmospheric and Hydrospheric Sciences

1992 - 1998: Chair, GSFC Library Committee

1992 - 1994: Chair and Founding Member, Goddard Mathematics Group

Awards


Other Professional Information


As of October 2022:

Total Citations: 5,190

Total Publications: 108

H-Index: 25

I10-Index: 35

Special Experience


2020 - 2021: Lead, PDT, SAMDA II Contract

2017 - 2021: Alt-COR, SAMDA Contract

2016: COR, Remote Sensing Systems (RSS) Contract

2015 - 2016: Member, PDT, Support for Atmospheres, Modeling and Data Assimilation (SAMDA) Contract

2012 - 2013: Member, SEB, Information Sciences and Library Services (ISLS) Contract

2011 - 2012: Member, SEB, Support for Atmospheric Sciences (SAS) Contract

2011: Member, SEB, Global Modeling and Assimilation Office (GMAO) Contract

2006 - 2017: COTR, Global Modeling and Assimilation Office (GMAO) Contract

2005: Chair, SEB, Global Modeling and Assimilation Office (GMAO) Contract

2000: Member, SEB, Laboratory for Atmospheres (LAS) Contract

Publications


Refereed

Gilpin, S., T. Matsuo, and S. E. Cohn. 2023. A generalized, compactly supported correlation function for data assimilation applications Quarterly Journal of the Royal Meteorological Society 149 (754): 1953-1989 [10.1002/qj.4490]

Wargan, K., B. Weir, G. L. Manney, et al. S. E. Cohn, K. E. Knowland, P. A. Wales, and N. J. Livesey. 2023. M2‐SCREAM: A Stratospheric Composition Reanalysis of Aura MLS Data With MERRA‐2 Transport Earth and Space Science 10 (2): e2022EA002632 [10.1029/2022ea002632]

Gilpin, S., T. Matsuo, and S. E. Cohn. 2022. Continuum Covariance Propagation for Understanding Variance Loss in Advective Systems SIAM/ASA Journal on Uncertainty Quantification 10 (3): 886-914 [10.1137/21m1442449]

Malings, C., K. E. Knowland, C. A. Keller, and S. E. Cohn. 2021. Sub‐City Scale Hourly Air Quality Forecasting by Combining Models, Satellite Observations, and Ground Measurements Earth and Space Science 8 (7): [10.1029/2021ea001743]

Wargan, K., B. Weir, G. L. Manney, S. E. Cohn, and N. J. Livesey. 2020. The Anomalous 2019 Antarctic Ozone Hole in the GEOS Constituent Data Assimilation System With MLS Observations Journal of Geophysical Research: Atmospheres 125 (18): [10.1029/2020jd033335]

Janjić, T., N. Bormann, M. Bocquet, et al. J. A. Carton, S. E. Cohn, S. L. Dance, S. N. Losa, N. K. Nichols, R. Potthast, J. A. Waller, and P. Weston. 2017. On the representation error in data assimilation Quarterly Journal of the Royal Meteorological Society 144 (713): 1257-1278 [10.1002/qj.3130]

Janjic, T., D. McLaughlin, S. E. Cohn, and M. Verlaan. 2014. Conservation of Mass and Preservation of Positivity with Ensemble-Type Kalman Filter Algorithms Mon. Wea. Rev. 142 (2): 755-773 [10.1175/MWR-D-13-00056.1]

Cacio, E., S. E. Cohn, and R. Spigler. 2012. Numerical treatment of degenerate diffusion equations via Feller's boundary classification, and applications Numerical Methods for Partial Differential Equations 28 (3): 807-833 [10.1002/num.20657]

Cohn, S. E. 2010. The principle of energetic consistency in data assimilation Data Assimilation: Making Sense of Observations Chapter 7 137--216 [10.1007/978-3-540-74703-1]

Cohn, S. E. 2009. Energetic Consistency and Coupling of the Mean and Covariance Dynamics Handbook of Numerical Analysis Vol. XIV, Special Volume: Computational Methods for the Atmosphere and the Oceans Chapter 10 443-478 [10.1016/s1570-8659(08)00210-x]

Janjić, T., and S. E. Cohn. 2006. Treatment of Observation Error due to Unresolved Scales in Atmospheric Data Assimilation Monthly Weather Review 134 (10): 2900-2915 [10.1175/mwr3229.1]

Gaspari, G., S. E. Cohn, J. Guo, and S. Pawson. 2006. Construction and application of covariance functions with variable length-fields Q.J.R. Meteorol. Soc. 132 (619): 1815-1838 [10.1256/qj.05.08]

Lyster, P. M., S. E. Cohn, B. Zhang, et al. L.-P. Chang, R. Menard, K. Olson, and R. Renka. 2004. A Lagrangian trajectory filter for constituent data assimilation Q. J. R. Meteorol. Soc. 130 (601): 2315-2334 [10.1256/qj.02.234]

Yang, R., S. Cohn, A. da Silva, J. Joiner, and P. R. Houser. 2003. Tangent linear analysis of the Mosaic land surface model J. Geophys. Res. 108 (D2): 4054 [10.1029/2002JD002410]

Zhu, Y., R. Todling, J. Guo, et al. S. E. Cohn, I. M. Navon, and Y. Yang. 2003. The GEOS-3 Retrospective Data Assimilation System: The 6-Hour Lag Case Mon. Weather Rev. 131 (9): 2129-2150 [10.1175/1520-0493(2003)131<2129:TGRDAS>2.0.CO;2]

Yang, R., S. E. Cohn, A. da Silva, J. Joiner, and P. Houser. 2003. Tangent linear analysis of the Mosaic land surface model J Geophys Res 108 (D2): 12-1 - 12-16

Tippett, M. K., and S. E. Cohn. 2001. Adjoints and low-rank covariance representation Nonlinear Processes in Geophysics 8 (6): 331-340 [10.5194/npg-8-331-2001]

Tippett, M. K., S. E. Cohn, R. Todling, and D. Marchesin. 2000. Low-dimensional representation of error covariance Tellus 52A (5): 533-553

Tippett, M. K., S. E. Cohn, R. Todling, and D. Marchesin. 2000. Conditioning of the Stable, Discrete-Time Lyapunov Operator SIAM. J. Matrix Anal. & Appl. 22 (1): 56-65 [10.1137/S0895479899354822]

M'enard, R., S. E. Cohn, L.-P. Chang, and P. M. Lyster. 2000. Assimilation of stratospheric chemical tracer observations using a Kalman filter. Part I: Formulation Monthly Weather Review 128 (8): 2654--2671

Gaspari, G., and S. E. Cohn. 1999. Construction of correlation functions in two and three dimensions Quarterly Journal of the Royal Meteorological Society 125 (554): 723-757 [10.1256/smsqj.55416]

Todling, R., S. E. Cohn, and N. S. Sivakumaran. 1998. Suboptimal Schemes for Retrospective Data Assimilation Based on the Fixed-Lag Kalman Smoother Monthly Weather Review 126 (8): 2274-2286 [http://dx.doi.org/10.1175/1520-0493(1998)126<2274:]

Li, Y., R. Ménard, L. P. Riishøjgaard, S. E. Cohn, and R. B. Rood. 1998. A study on assimilating potential vorticity data Tellus A 50 (4): 490-506 [10.1034/j.1600-0870.1998.t01-2-00008.x]

Riishojgaard, L., S. E. Cohn, Y. Li, and R. M'enard. 1998. The use of spline interpolation in semi-Lagrangian transport models Monthly weather review 126 (7): 2008--2016

Cohn, S. E., A. Da Silva, J. Guo, M. Sienkiewicz, and D. Lamich. 1998. Assessing the Effects of Data Selection with the DAO Physical-Space Statistical Analysis System* Monthly Weather Review 126 (11): 2913--2926

Cohn, S. E. 1997. An introduction to estimation theory JOURNAL-METEOROLOGICAL SOCIETY OF JAPAN SERIES 2 75 147--178

Kalnay, E., D. L. Anderson, A. F. Bennett, et al. A. J. Busalacchi, S. E. Cohn, P. Courtier, J. Derber, A. C. Lorenc, D. Parrish, and T. Schlatter. 1997. Data assimilation in the ocean and in the atmosphere: what should be next? Journal of the Meteorological Society of Japan 75 (1B): 489--496

Lyster, P., S. E. Cohn, R. Menard, et al. L. Chang, S. Lin, and R. Olsen. 1997. Parallel implementation of a Kalman filter for constituent data assimilation Monthly weather review 125 (7): 1674--1686

Cohn, S. E., and R. Todling. 1996. Approximate data assimilation schemes for stable and unstable dynamics JOURNAL-METEOROLOGICAL SOCIETY OF JAPAN SERIES 2 74 63--75

Todling, R., and S. E. Cohn. 1994. Suboptimal Schemes for Atmospheric Data Assimilation Based on the Kalman Filter Monthly Weather Review 122 (11): 2530-2557 [http://dx.doi.org/10.1175/1520-0493(1994)122<2530:]

Cohn, S. E., N. S. Sivakumaran, and R. Todling. 1994. A fixed-lag Kalman smoother for retrospective data assimilation Monthly Weather Review 122 (12): 2838-2867 [http://dx.doi.org/10.1175/1520-0493(1994)122<2838:]

Cohn, S. E. 1993. Dynamics of short-term univariate forecast error covariances Monthly weather review 121 (11): 3123--3149

Augenbaum, J., S. E. Cohn, and D. Marchesin. 1991. Eliminating grid-orientation errors in alternating-direction implicit schemes Applied Numerical Mathematics 8 (1): 1-10 [10.1016/0168-9274(91)90094-g]

Cohn, S. E., and D. F. Parrish. 1991. The behavior of forecast error covariances for a Kalman filter in two dimensions Monthly Weather Review 119 (8): 1757--1785

Cohn, S. E., and D. P. Dee. 1989. An analysis of the vertical structure equation for arbitrary thermal profiles Quarterly Journal of the Royal Meteorological Society 115 (485): 143-171 [10.1002/qj.49711548508]

Cohn, S. E., and D. P. Dee. 1988. Observability of Discretized Partial Differential Equations SIAM Journal on Numerical Analysis 25 (3): 586-617 [10.1137/0725037]

Dee, D., S. Cohn, A. Dalcher, and M. Ghil. 1985. An efficient algorithm for estimating noise covariances in distributed systems IEEE Transactions on Automatic Control 30 (11): 1057-1065 [10.1109/tac.1985.1103837]

Augenbaum, J. M., S. E. Cohn, E. Isaacson, D. P. Dee, and D. Marchesin. 1985. A factored implicit scheme for numerical weather prediction Comm. Pure Appl. Math. 38 (5): 503-517 [10.1002/cpa.3160380504]

Cohn, S. E., D. Dee, D. Marchesin, E. Isaacson, and G. Zwas. 1985. A fully implicit scheme for the barotropic primitive equations Monthly weather review 113 (4): 436--448