Joseph C. Chang

Joseph C. Chang
Senior Physical Scientist


PhD in computational science and informatics, George Mason University; MS in meteorology, Massachusetts Institute of Technology; BS in atmospheric science, National Taiwan University


Joseph Chang is a senior physical scientist at RAND. He has more than 35 years of experience in diverse technical areas, including border security, immigration, chemical security, transportation security, infrastructure protection, risk assessment, operational analysis, analysis of alternatives, performance measurement, climate change, environment, air pollution, plume modeling, data analytics, and model verification and validation. He developed the modified repeated trials model that estimates the flow of illegal migrants successfully crossing the border, including those who were previously or never apprehended. He developed an optimization-based strategic sampling framework to assess the performance of the current surveillance technology allocation along the U.S.-Mexico border and inform policy questions. He led the efforts in developing the Border Condition Index that holistically assesses the conditions of the border. He provided critical scientific guidance on the Department of Homeland Security’s Jack Rabbit field program involving releases of 2 to 20 tons of chlorine, for the purpose of improving modeling algorithms and first responder training. He is a world renowned expert in dispersion modeling. The evaluation methodology and acceptance criteria that he developed for dispersion models are widely used by scientists throughout the world. He has been organizing the annual George Mason University Conference on Atmospheric Transport and Dispersion Modeling for more than 15 years. He is a Certified Consulting Meteorologist, a certification program administered by the American Meteorological Society (AMS). He served on various AMS boards and committees, and is currently a co-chair of an AMS committee to explore a new climate-change consulting certification program.

Selected Publications

Chang, J., T. Mazzola, and S.R. Hanna, "Development of a quality-controlled chlorine gas concentration data base for the Jack Rabbit II field experiments," Atmospheric Environment, 246, 2021

S.R. Hanna, J.C. Chang, and T. Mazzola, Comparison of an Analytical Urban Puff-Dispersion Model with Tracer Observations From the Joint Urban 2003 Field Campaign, Boundary-Layer Meteorology, 2019

S.R. Hanna, P.J. Drivas, and J.C. Chang, Guidelines for Use of Vapor Cloud Dispersion Models, 2nd edition, American Institute of Chemical Engineers, 1996

S.R. Hanna and J.C. Chang, "Dependence of maximum concentration from chemical accidents on release duration," Atmospheric Environment, 148, 2017

S.R. Hanna J.C. Chang, and P. Huq, "Observed chlorine concentrations during Jack Rabbit I and Lyme Bay field experiments," Atmospheric Environment, 125, 2016

J. Pullen, J. Chang, and S. Hanna, "Air/sea transport, dispersion and fate modeling in the vicinity of the Fukushima nuclear power plan: A Special Conference Session Summary," Bulletin of American Meteorological Society, 94, 2013

J.C. Chang and S.R. Hanna, "Air quality model performance evaluation," Meteorology and Atmosphric Physics, 87, 2004

S.R. Hanna, and J.C. Chang, "Skyscraper rooftop tracer concentration observations in Manhattan and Comparisons with urban dispersion models," Atmospheric Environment, 106, 2015