Scientific Leadership

Exceptional Contributors to AER and the Larger Community

AER staff members serve as faculty and instructors at area universities, and serve with university and government colleagues on numerous committees, such as those of the National Research Council. AER staff are active participants in professional journal review boards as well as panel and mail proposal reviews for government agencies. AER scientists also actively participate in the workings of such professional organizations as the American Meteorological Society (AMS) and the American Geophysical Union (AGU). AER scientists have served as President of the AMS and as Vice Chairman of the ECMWF Scientific Advisory Committee.

Shepard A. Clough

Mr. Clough's principal areas of interest include atmospheric radiative transfer, molecular physics, and approaches to the retrieval of information from remotely sensed measurements. Mr. Clough's current activities are focused on the improvement of radiative transfer modeling for general circulation models with application to climate change studies. Mr. Clough is a member of the Science Team of the Atmospheric Radiation Measurement program (ARM) for which his responsibilities include the development, improvement and validation of radiative transfer models. He is a participant in the Earth Observing System (EOS) as a co-investigator on the Tropospheric Emission Sounder (TES), a high resolution spectrometer to be flown on the EOS CHEM mission. He has been responsible for the development of the widely used atmospheric radiative modeling codes including LBLRTM, RRTM, and CHARTS, and has made significant contributions to the HITRAN spectroscopic database. Mr. Clough is well known for his contributions to the theory of collision broadening as applied to atmospheric problems including the water vapor continuum. His current activities include the application of spectroscopic techniques to attain improvements in atmospheric remote sensing. Mr. Clough is currently a member of the ARM Science Team Executive Committee and a member of the International Radiation Commission.

Judah Cohen, Ph.D.

Dr. Cohen joined AER as a staff scientist in 1998, having previously spent two years as a National Research Council Fellow at the NASA Goddard Institute for Space Studies and then two years as a research scientist at MIT's Parsons Laboratory. Cohen received his Ph.D. in Atmospheric Sciences from Columbia University in 1994 and has since focused on conducting numerical experiments with global climate models and advanced statistical techniques to better understand climate variability and to improve climate prediction. In addition to his research interests, Cohen is leading AER's development of seasonal forecast products for commercial clients. A member of the American Meteorological Society and the American Geophysical Union, Cohen has published over two dozen articles in their journals and others.

Janusz Eluszkiewicz, Ph.D.

Dr. Eluszkiewicz holds a MSc in physics from Warsaw University, a PhD in planetary science from Caltech, and has acquired additional educational and professional experience at other leading institutions, including Oxford and MIT. In addition to his position in the Research and Development Division at AER, he is a staff member in the Department of Earth and Atmospheric Sciences at Harvard. Dr. Eluszkiewicz is an interdisciplinary scientist, with numerous publications in scientific journals and books. His interests range from the atmospheres and surfaces of Earth and Mars to the physics of volatile ices in the Outer Solar System. Currently, Dr. Eluszkiewicz is the Principal Investigator on several projects funded by NASA and the Department of Defense.

Gary Gustafson

Mr. Gustafson has been active in the field of remote sensing of cloud and precipitation systems from passive space-borne sensors and active ground based systems for over twenty years. Recent work has focused on development and real-data testing of retrieval techniques for cloud and aerosol properties using satellite and aircraft based electro-optical sensor measurements. Particular emphasis has been on the application of those techniques to operational programs. Research interests include identification of cloud spectral signatures in multispectral sensor data, inference of cloud macrophysical properties through spatial and spectral clustering approaches, and interactive image processing and visualization for manual scene interpretation. He has participated in numerous studies for both commercial and governmental organizations including the Air Force Research Laboratory, the Air Force Weather Agency, Defense Meteorological Satellite Program, Strategic Environmental Research and Development Program, Defense Modeling and Simulation Office, ITT, Sterling Software, EarthSat, FAA, MIT Lincoln Laboratory, Defense Mapping Agency, and the Bureau of Reclamation.

Alan Lipton, Ph.D.

While at AER, Dr. Lipton has developed algorithms, managed and conducted research in support of the development of the Conical-Scanning Microwave Imager/Sounder (CMIS), an instrument that is planned for flight on satellites of the National Polar-Orbiting Operational Environmental Satellite System (NPOESS). Dr. Lipton has also performed research on radiative transfer and assimilation of satellite data in numerical weather prediction models. Prior to joining AER, he planned, executed, and reported results of research projects involving methods for retrieving meteorological information from satellite data and exploiting satellite data to improve numerical weather analysis and prediction. The work incorporated radiative transfer computation, meteorological analysis, mesoscale modeling, and data assimilation.

Eli Mlawer, Ph.D.

Dr. Mlawer’s main areas of interest include atmospheric radiative transfer, climate study, and the characterization of molecular collisional broadening. As part of his involvement in the DoE Atmospheric Radiation Measurement (ARM) Program, Dr. Mlawer is the coordinator of the Broadband Heating Rate Profile VAP, an effort to compute fluxes and heating rates in clear and cloudy conditions at the ARM sites and to perform a closure analysis on these calculations using surface and TOA radiation measurements. He has primary responsibility for the design, implementation, and validation of RRTM, a radiative transfer model for climate applications used by many climate and NWP models. Dr. Mlawer is a key participant in the research being conducted with a number of climate models utilizing RRTM, and continues to actively partake in the Intercomparison of Radiation Codes in Climate Models effort. He is the lead developer of the MT_CKD water vapor continuum model, a new formulation of the well-regarded CKD continuum. In recent research, Dr. Mlawer utilized spectral comparisons of solar irradiance measurements and calculations to determine that there are no unknown molecular absorbers of significance in the solar regime, as had been previously suggested.

George Modica

Mr. Modica's work in exploratory development studies in numerical mesoscale analysis and forecasting, including four-dimensional data assimilation of satellite data, development of microphysics parameterizations for aircraft icing studies, assessment of the effect of complex soil and vegetation parameterizations on the evolving mesoscale fields has been of direct benefit to his DoD clients. His work continues in advanced development activities including technology transition of diagnostic turbulence and icing algorithms to the Air Force Weather Agency.

Thomas Nehrkorn, Ph.D.

Dr. Thomas Nehrkorn, Senior Staff Scientist and Director of Tropical Forecasting in the Numerical Weather Prediction Group, has been with Atmospheric and Environmental Research, Inc. since 1985. He received his Ph.D. in Meteorology from MIT with Kerry Emmanuel as his thesis advisor. Prior to that, Dr. Nehrkorn studied and received his M.S. in Atmospheric Science from Colorado State University under William Cotton, and his B.S in Meteorology from The University of Hamburg, Germany.

Dr. Nehrkorn's 22 year research tenure at AER has included work on numerical weather prediction models, data assimilation systems, humidity to cloud relationships, three dimensional analysis of atmospheric quantities and studies of the angular momentum budget of the atmosphere. His prior work in hurricane modeling focused on probabilistic track and intensity forecasts resulting in the release of a hurricane track forecast product in late 2001. Currently he oversees the production of the short range probabilistic hurricane forecast for CHI Futures contracts trading and a long range consulting service for the insurance and reinsurance industry. His research activities revolve around tropical cyclone simulations and prediction models, 3D and 4D variational analysis schemes, ensemble forecasting techniques and coupling of mesoscale Numerical Weather Prediction (NWP) models to Atmospheric Transport and Dispersion (ADT) models.

He is a member of the American Meteorological Society (AMS) and the American Geophysical Union (AGU) and has published and presented over 80 papers in refereed journals and technical conferences.

Rui Ponte, Ph.D.

Dr. Ponte researches atmospherically-driven sea level and bottom pressure variability, ocean angular momentum and Earth's variable rotation and gravity field, mechanisms of exchange of angular momentum among the oceans, atmosphere and solid Earth, intraseasonal variability in the tropical atmosphere and oceans, and influence of topography and variable mixing on the deep circulation. He serves as an investigator on NASA's Earth Observing System Project, is a science team member on NASA-CNES altimeter missions (TOPEX/Poseidon, Jason-1) and on the Gravity Recovery and Climate Experiment (GRACE) mission. Dr. Ponte also serves as a member of IAU/IUGG Working Group on Non-Rigid Earth Nutation Theory, IAG Special Study Group on Interactions of the Earth's Rotational Dynamics with the Oceans and Atmospheres, and IERS Special Bureau for the Ocean.

Betty Pun, Ph.D.

Dr. Pun is a senior scientist in AER's Air Quality Division located in San Ramon, California, USA. She holds a B.S. in chemical engineering from the California Institute of Technology and M.S. and Ph.D. in chemical engineering from the Massachusetts Institute of Technology. She has extensive experience in air quality modeling, particularly in the application of CMAQ and CAMx to ozone, PM, and air toxics. She has applied CMAQ to many regions of the United States including California, Texas, the southeastern U.S., the central/eastern U.S. and the northeastern U.S. She has applied CAMx to several regions in North America, including the central/eastern United States and the Houston area. Dr. Pun is an expert in organic aerosol modeling; she has developed several models that are currently used in CMAQ and other 3-D models and she is currently leading the development of the next-generation secondary organic aerosol module for 3-D air quality models. She has published over 20 peer-reviewed articles in the scientific literature.

David A. Salstein, Ph.D.

Dr. Salstein focuses on diagnostic studies of atmospheric and oceanic circulation at AER. He is well known for his contributions to the study of the exchange of angular momentum between atmosphere and solid Earth, and as such, is an active participant of the International Earth Rotation Service, having helped establish and operate its atmospheric component. He has been an investigator on a number of NASA, NOAA and NSF projects and missions relating to atmospheric circulation, Earth system dynamics, and climate variability.

William H. Smyth, Ph.D.

Dr. Smyth received his Ph. D. in Applied Physics from Harvard University with a subject major in plasma physics and with subject minors in fluid mechanics and applied mathematics. His primary research interests are the theoretical modeling of a range of physical problems in the solar system involving gases and plasma, and their complex interactions in atmospheres, magnetospheres, and in the solar wind. These interests include the local and extended atmospheres of planets, satellites, and comets and involve the solutions of kinetic theory regimes that range in nature from collisionless to fully collisional. Particular research topics include the development of photochemical models for the atmosphere of Venus to understand the formation of sulfuric acid clouds surrounding the planet and the development of comprehensive exospheric models to investigate the novel sodium and potassium atmospheres of Mercury and the Moon as well as the coronae of Io. In the last thirty years, Dr. Smyth has pioneered research in the subject of extended neutral atmospheres of satellites, with Io and more recently Europa and their impact as an internal plasma source on the magnetosphere of Jupiter being a central topic. He is an active member of the American Geophysical Union and the American Astronomical Society and was as an Interdisciplinary Scientist for the Galileo Spacecraft Mission of NASA.

Hilary E. "Ned" Snell, Ph.D.

Dr. Snell is experienced in both theoretical and experimental remote sensing. This includes extensive infrared and ultraviolet radiative transfer model and retrieval algorithm development, the design and implementation of upgrades to the FASCODE and LBLRTM algorithms, the design and construction of infrared remote sensing instrumentation, and the analysis of data acquired from ground-based and space-borne sensors. Recently he led the development of the infrared ozone retrieval algorithm for the Ozone Mapping and Profiling Suite (OMPS) as part of National Polar Orbiting Operational Satellite System (NPOESS). He is currently AER's project manager for the Cross-track Infrared Microwave Sounder Suite (NPOESS-CrIMSS), developing algorithms for the retrieval of pressure, temperature, and moisture profiles.

T. Scott Zaccheo, Ph.D.

Dr. Zaccheo is an expert in image processing and systems engineering and has spent the last fifteen applying engineering principles to the process of acquiring and analyzing scientific data. At AER, Dr. Zaccheo has been the primary architect of numerous scientific systems including an interactive suite of analysis tools designed to assess the performance of retrieval algorithms associated with heritage and next-generation earth observing environmental sensors. He has also been a member of a research team responsible for the design and analysis of inverse methods for retrieving atmospheric moisture and temperature profiles from microwave and infrared sounder data. Prior to joining AER, Dr. Zaccheo worked on characterization of IR clutter and the assessment of its impact on detection and estimation techniques at Lincoln Laboratory. He has also been a contributing member of the Solar and Heliospheric Observatory (SOHO) and Hubble Space Telescope (HST) algorithm teams. He has authored or coauthored more than a dozen scientific papers and hold three degrees in electrical engineering, including the Ph.D. from Tufts University.