Stephen E Cohn

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Stephen E Cohn

  • RESEARCH AST, METEOROLOGICAL STUDIES
  • 301.614.6168 | 301.614.6297
  • NASA/GSFC
  • Mail Code: 610.1
  • Greenbelt , MD 20771
  • Employer: NASA
  • Research Interests

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

    Positions/Employment

    1991 - Present

    Research Meteorologist, Computer Scientist, Mathematician

    NASA Goddard Space Flight Center, Greenbelt, Maryland
    1991 - 1991

    Research Scientist

    Universities Space Research Association, Greenbelt, Maryland
    1990 - 1991

    UCAR Senior Fellow

    National Meteorological Center, Camp Springs, Maryland
    1988 - 1988

    Visiting Professor

    Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
    1987 - 1987

    Visiting Professor

    Universita di Catania, Catania, Italy
    1983 - 1985

    Visiting Professor

    Pontificia Universidade Catolica do Rio de Janeiro, Rio de Janeiro, Brazil
    1982 - 1991

    Assistant Research Scientist through Research Assistant Professor

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

    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

    2014 - Present: 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 - Present: 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

    2011: Technical Person of the Year, NASA HQ Office of Small Business Programs

    Other Professional Information

    As of November 2016:

    Total Citations: 3,365

    Total Publications: 90

    H-Index: 21

    Special Experience

    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 - Present: 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

    Selected Publications

    Refereed

    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]

    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]

    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]

    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]

    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]

    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.

    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]

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

    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]

    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.

    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]

    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:]

    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.

    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:]

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

    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.

    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. 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]

    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.

    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]

    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]

    Selected Publications

    Refereed

    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]

    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]

    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]

    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]

    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]

    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

    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]

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

    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]

    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

    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]

    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:]

    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

    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:]

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

    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

    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. 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]

    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

    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]

    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]

                                                                                                                                                                                            
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