The Weather & Chaos project of the University of Maryland, College Park (UMCP) was started by Distinguished Professor Eugenia Kalnay of Department of Atmospheric and Oceanic Science and Distinguished Professor Jim Yorke of the Institute for Phyical Science and Technology in 2000. They assembled a group of experts to carry out interdisciplinary research in numerical weather prediction, dynamical system theory and scientific computation. The goal was to conduct research that would lead to a better understanding of the behavior of high-dimensional spatio-temporally chaotic systems, such as the atmosphere, and to improved techniques for numerical weather prediction. The initial funding for the project was generously provided by the W. M. Keck Foundation.

Since it was launched in 2000, the project has grown into a major informal research and educational program at UMCP.The project has led   to the publication of many papers in leading atmospheric science and physics journals and to over a dozen Ph. D. dissertations in the Atmospheric and Oceanic Science, Physiscs, Mathematics, Applied Mathematics and Scientific Computation and Electrical Engineering doctoral programs .

The most important product of our research efforts is the Local Ensemble Transform Kalman Filter (LETKF; Hunt et al. 2007) data assimilation system. This system allows for the estimation of the state of large spatio-temporally chaotic systems, such as the atmosphere, based on incomplete observations and a possibly imperfect numerical model of the system. In addition to the UMCP scientists involved in the project, scientists from the Arizona State University, Tempe, AZ and the George Mason University, Fairfax, VA have also made important contributions to the development of the algorithm and the computer code.   The LETKF has been successfully tested on the Global Forecast System model (GFS) of the National Centers for Environmental Prediction/National Weather Service (NCEP/NWS) on the Regional Spectral Model (RSM) of NCEP/NWS, on the Finite-Volume Global Circulation Model of the NASA Goddard Space Flight Center and on a numerical model of laboratory convection. Current efforts of the Weather and Chaos Project include implementation of the LETKF on the Geophysical Fluid Dynamics Laboratory Mars General Circulation Model (GFDL Mars GCM), in collaboration with NOAA GFDL, Princeton, NJ and the Atmospheric and Environmental Research Inc., Lexington, MA and the development of an LETKF-based system for the coupled assimilation of weather and carbon   observations to study the carbon cycle in the Earth system, in collaboration with the University of California, Berkley, CA and the Lawrence Livermore National Laboratory, Livermore, CA of the   Department of Energy. The LETKF has been adopted as the next operational global data assimilation system system by CPTEC (Center for Weather prediction and climate studies of Brazil) and is  being tested at the Japanese Meteorological Agency. The LETKF is also being tested for coastal   limited area data assimilation with an implementation on the Estuarine and Coastal Ocean Model (ECOM) by AER Inc, It is implemented into the Regional Ocean Modeling System (ROMS) on California coastal ocean dnd the Chesapeake Bay in collaboration with University of California, Los Angeles. A computationally highly efficient parallel FORTRAN code is available for download.