Steven Hanna

Adjunct Associate Professor of Environmental Health

Department of Environmental Health

Landmark Center
401 Park Drive
Boston, Massachusetts 02215
Phone: 207.967.4478


Ph.D., M.S., B.S.          Meteorology, Penn State University (1967, 1966, 1964)


April 2002-Present: Adjunct Associate Professor, Harvard School of Public Health, Boston, MA
July 1997- July 2003: Research Professor, George Mason University, Fairfax, VA
April 1997-Dec. 2000: Research Associate, Harvard School of Public Health, Boston, MA
April 1997-Present: President, Hanna Consultants, Kennebunkport, ME
1992-April 1997: Principal Meteorologist, Earth Tech, Inc., Concord, MA
1985-1992: Founder and Vice President, Sigma Research Corp., Westford, MA
1981-1985: Principal Meteorologist, Environmental Research & Technology, Inc.(ERT), Concord, MA
1967-1981: Research Meteorologist and Acting Director (1979-1981) USDOC/NOAA, Environmental Research Laboratories, Atmospheric Turbulence and Diffusion Laboratory, Oak Ridge, TN


Dr. Hanna is the 1994 recipient of the American Meteorological Society’s Award for Outstanding Contribution to the Advance of Applied Meteorology, and is a 1996 Centennial Fellow of the College of Earth and Mineral Sciences of Penn State University.  In January, 2005, he was named a Fellow of the American Meteorological Society.  In January 2010, he received the AMS Helmut E. Landsberg award for “Significant novel and insightful contributions in applied meteorology and urban studies, including field work, data interpretation, model development, and model evaluation”.  In January 2015, he received the AMS Henry Harrison Award for Certified Consulting Meteorologists.  In January 2016, he received the AMS award for Outstanding Scientific Contributions in Meteorological Aspects of Air Pollution.

Professional Summary

Dr. Hanna is a specialist in atmospheric turbulence and dispersion, in the analysis of meteorological and air quality data, and in the development, evaluation, and application of air quality models.  He is an AMS Certified Consulting Meteorologist with over 45 years of experience.  He has led several research and development projects involving, for example, the analysis of uncertainties of dispersion models, the statistical evaluations of hazardous gas dispersion models and regional ozone models, the development of models for the dispersion of emissions from tall power plant stacks, from offshore oil platforms, and from accidental and intentional releases of hazardous chemicals, and the analysis of data from large urban and regional field experiments.  From 1988-1997, Dr. Hanna was Chief Editor of the Journal of Applied Meteorology, and has published over 160 articles in refereed journals, six chapters in books, and five books in which he is the primary author.

Related Professional Experience

 Model Evaluation, Model Uncertainty, and Concentration Fluctuations

A statistical method for evaluating air quality models was developed by Dr. Hanna and applied to many types of source scenarios, models, and field data sets. This method is now accepted as a standard in international research on dispersion model evaluation (e.g., see  The U.S. Air Force, the U.S. Army, and the American Petroleum Institute supported the further development of a framework for evaluating and for estimating the uncertainty in environmental models.  During the past few years, the Department of Defense, the Department of Energy, the Environmental Protection Agency, and the Department of Homeland Security have sponsored additional studies of model evaluation methods, with emphasis on scenarios where chemical or biological agents might be released.

From 1993 through 2006, the Electric Power Research Institute supported the development of uncertainty analysis methods for photochemical grid models.  The Nuclear Regulatory Commission has had Dr. Hanna review their uncertainty analysis methods for linked emissions-dispersion-exposure-risk consequence models. The American Petroleum Institute has had Dr. Hanna lead a long-term study in which the uncertainties of dispersion models for toxic gases in urban areas were investigated.

From 2004 through 2007, Dr. Hanna was a lead scientist in a Defense Threat Reduction Agency (DTRA) study involving improvements of methods to account for mesoscale and regional-scale uncertainties in transport and dispersion estimates.

From 2006 through the present, Dr. Hanna has led model evaluation efforts for the HPAC-SCIPUFF model, for urban dispersion models, and for the JEM model (supported by DOD).  He has been (since 2014) part of the scientific advisory team in which many countries’ urban puff dispersion models are being compared using the JU2003 tracer observations.  The study, UDINEE, is funded by the European Commission

Regional Air Quality Data Analysis and Model Evaluation

Dr. Hanna was the chief scientist for analysis of field data from several regional and urban-scale ozone experiments, including the South Central Coastal Cooperative Aerometric Monitoring Program (SCCCAMP), the Lake Michigan Ozone Study (LMOS), and the Gulf of Mexico Air Quality Study (GMAQS).  From 1999 through 2005, Dr. Hanna was the chief scientist on two DOI/MMS-sponsored studies involving boundary layers and air quality in the Gulf of Mexico.  He led a ten-year effort in which the effects of uncertainties in input parameters on the uncertainties in predictions of regional air quality models were assessed using Monte Carlo methods.  In 2005, Dr. Hanna completed a study of the uncertainties in the BEIS3 model, which is used to estimate biogenic emissions for input to photochemical grid models.

Modeling of Turbulence and Diffusion

Dr. Hanna has developed applied diffusion models for several industrial and governmental clients, including a diffusion model for complex terrain (RTDM), a model for overwater diffusion (OCD), a cooling tower plume model (ATCOOL), a model for diffusion from tall stacks (HPDM), a hazardous gas model for chemical reactions and thermodynamics associated with UF6 releases, and a baseline urban dispersion model.

In the past ten years, Dr. Hanna’s baseline urban dispersion model was further enhanced for use in estimating impacts of possible terrorist attacks with chemical and biological agents. It was evaluated with field data from Los Angeles, Salt Lake City, Oklahoma City, and New York City.  He led the evaluation of DTRA’s HPAC-Urban model with field data from Oklahoma City and New York City.  He was the chief scientist of the Madison Square Garden-2005 (MSG05) tracer experiment in New York City.  From 2012-2016, he analyzed the rooftop urban observations during the MID05 field experiment and developed algorithms to better estimate rooftop concentrations in city centers.

Hazardous Gas Model Development and Analyses

The American Institute of Chemical Engineers (AIChE) Center for Chemical Process Safety (CCPS) sponsored the writing of the Guidelines for Use of Vapor Cloud Dispersion Models in 1987, and the preparation of greatly-enhanced second edition in 1996.   The AIChE/CCPS also sponsored preparation of the 2002 book entitled Wind Flow and Vapor Cloud Dispersion at Industrial and Urban Sites.

A USAF/API study was completed in which 15 hazardous gas models were evaluated with data from 8 field studies.

An industry-government consortium supported the five-year PERF 93-16 Dispersion Modeling Project, including field and laboratory experiments, in which dense gas models were improved so that they account for high surface roughnesses, short-duration releases, and stable ambient conditions.  Dr. Hanna was responsible for the planning and coordination of the technical components of the project and carried out the analysis of the Kit Fox field data and the evaluation of the HGSYSTEM 3+ model.

From 2005 through the present, Dr. Hanna has led DARPA, DHS, and DTRA studies of emissions and dispersion of chlorine, anhydrous ammonia, and other Toxic Industrial Chemicals (TICs) released from railcars.  In the DTRA study, source emission model improvements were made for TICs.  He analyzed the observations from the DHS Jack Rabbit I chlorine and anhydrous ammonia field experiments, and is a member of the Scientific Advisory Board.  He has been lead scientist for the Jack Rabbit II field experiments (in August 2015 and August 2016), where up to 20 tons of pressurized liquefied chlorine was released in each trial.

 Hazardous Gas Modeling for DTRA, DOE-CBNP, and DHS

From 1997-2002, Dr. Hanna was the director and chief scientist of the Coordinated Hazardous Atmospheric Release Modeling (CHARM) project at George Mason University.  The research, supported by the Defense Threat Reduction Agency (DTRA), was concerned with development and evaluation of mesoscale meteorological models and atmospheric dispersion models for releases of chemical and biological agents.  Also, from 2000 through the present, DHS is supporting studies focused on improvements in guidance given to emergency responders concerning transport and dispersion in urban areas.

Research on Source Term Estimation

     Since 2013, Dr. Hanna has been on the scientific advisory and review panel for several large field experiments intended to improve Source Term Estimation (STE) of methane. In 2015-2016, he led an industry supported technical review of the field (including all pollutants) and published a summary article in Atmospheric Environment.

Support of Permitting Activities for Nuclear Reactors

      Over the past ten years, Dr. Hanna has worked on meteorological analyses and report writing as part of permits for several nuclear reactors.  The plants include Callaway, Nine Mile Point, Pilgrim, Davis-Besse, Indian Point, and Seabrook.  Dr. Hanna testified at the Pilgrim hearing in 2011.  In all of these cases, his work focused on support of use of the MACCS2/ATMOS model.  He carried out analyses of plant and other local meteorological data in the SAMA domain (50 mile radius) in order to justify use of the plant data in the ATMOS model.  In addition, Dr. Hanna has been supported by BP, Mitsubishi Heavy Industries and the Japan Nuclear Agency in various studies related to the Fukushima accident. He was co-organizer of a March 2015 Workshop at Fukushima University regarding applications of transport and dispersion models to nuclear plant accidents.

Reviews of Diffusion Research

Dr. Hanna has been requested to prepare written reviews of various aspects of diffusion research by many national and international agencies, industries, and universities.  He is a member of peer-review panels for NRC, DOE, EPA, CDC, DHS, CARB, and DOD programs.  In March, 1997, he chaired the Peer Review Panel for the Atmospheric Modeling Division of the EPA National Exposure Research Laboratory.  In June, 2000, he was a member of the Peer Review Panel for the EPA research program on ozone and air toxics.   In November, 1997, he chaired the Peer Review Panel for the U.S. modeling program for the Khamisiyah, Iraq, chemical releases.  In 1998 he chaired the Peer Review Panel for the EPA’s new AERMOD model.  In 2000, he was member of the Peer Review Panel for the Army Research Office’s Atmospheric Boundary Layer Program.  In 2003, he was a reviewer of the DOE VTMX research program. In 2005, he was a reviewer of the DTRA Chemical/Biological Defense Science Program. In 2009, he gave a keynote address at the Workshop on Evaluations of IMAAC models (for DHS).  From 2013-2018 he was an advisor to the EPA CASAC SOx panel.  In 2019, he is a member of the international peer review committee for the Swedish FOI research group.

Teaching Experiences at Universities

Dr. Hanna has been an adjunct professor and/or research professor at four universities during his career (Vanderbilt University from 1969 through 1973, University of Tennessee from 1974 through 1981, Harvard School of Public Health from 1983 through the present, and George Mason University from 1997 through 2002).  Approximately once each year throughout this period, he has taught graduate-level courses in atmospheric turbulence and dispersion. The Vanderbilt and UT lectures were used as the basis for the textbook by Hanna, Briggs, and Hosker (1982), which has been widely adopted as a basic text at other universities.  In addition, three or four times a year from 1987-1997, Dr. Hanna taught a two-day short course entitled “Vapor Cloud Dispersion” as part of AIChE/CCPS conferences.  Since 2002, he has taught 8 to 16 lectures a year in Air Quality Meteorology graduate-level courses at HSPH in Boston and in their International Institute in Cyprus. The lectures include hands-on training in use of AERMOD.

Business Experience

In 1985, Dr Hanna was a cofounder of Sigma Research Corporation, which carried out basic and applied research on meteorology and air quality issues for a variety of clients.  The company grew successfully and was purchased by Earth Tech in 1992.  In 1997, Dr. Hanna founded Hanna Consultants, where, currently, he spends about 95 % of his time.  The other 5 % of his time is spent at Harvard School of Public Health.

Expert Witness

      Dr. Hanna has provided testimony in depositions in several litigation cases and has testified in two trials and at two hearings.  In most of these cases, he was required to apply and interpret atmospheric transport and dispersion models.  He has modeled releases of methyl mercaptan, ammonia and chlorine from rail cars, oleum from valve ruptures, anhydrous ammonia from a tank rupture, sulfuric acid from a stack, hydrogen sulfide from a missile spill, water vapor and particulates from paper mills and cooling towers, small particles and ozone from power plants over the eastern U.S., wind flows in Manhattan street canyons, and wind patterns and dispersion of potential releases from nuclear power plants.

In January 2018, Dr. Hanna organized and was main speaker and moderator of an AMS Short Course on Forensic Meteorology.

Professional Organizations

Member of AMS, AGU, and AWMA

For the American Meteorological Society (AMS), he participated in the following volunteer activities.  Certifications and awards are also listed.

AMS:   Chief Editor, Journal of Applied Meteorology, 1988-1997

Chairman, 1974 Atmos. Turb. and Diff. Conference, Santa Barbara
Chairman, Atmos. Turb. and Diff. Committee, 1977‑1978
Member, AMS/EPA Cooperative Work Group, 1979‑1981
AMS Certified Consulting Meteorologist (Number 361)   1983

Recipient of 1994 AMS Award for Outstanding Contribution to the Advance of Applied Meteorology
Member, AMS Board on Urban Meteorology, 2002-2009
Co-Chairman of Urban Environment Conferences in 2004 (Vancouver) and 2006 (Atlanta)
Fellow, 2005
Co-Chairman of 2006 Forum on Managing our Physical and Natural Resources: Successes and Challenges, Annual Meeting, Atlanta
Chairman of F.A. Gifford Memorial Session at AMS Annual Meeting, 2008
Recipient of 2010 AMS Helmut E. Landsberg Award for “Significant novel and insightful contri-butions in applied meteorology and urban studies, including field work, data interpretation, model development, and model evaluation”.

Elected AMS Councilor, December 2013
Recipient of 2015 AMS Henry Harrison Award for Certified Consulting Meteorologists.
Recipient of 2016 AMS award for Outstanding Scientific Contributions in Meteorological Aspects of Air Pollution.
Member, AMS Board of Certified Consulting Meteorologists, 2015-2019