Kalnay was born in Argentina and received her undergraduate degree in meteorology from the University of Buenos Aires in 1965. In 1971, Kalnay became the first woman to receive a PhD in meteorology from MIT, where she was advised by Jule Charney. She then became the first female professor in the MIT Department of Meteorology. In 1979 she moved to NASA Goddard and in 1984 became Head of the Global Modeling and Simulation Branch at the Goddard Laboratory for Atmospheres. From 1987 to 1997, Kalnay was the Director of the Environmental Modeling Center of the National Centers for Environmental Prediction, National Weather Service and oversaw the NCEP/NCAR reanalysis project and numerous other projects in data assimilation and ensemble forecasting. After leaving NCEP, Kalnay became the Robert E. Lowry Chair of the School of Meteorology at the University of Oklahoma. In 2002, Kalnay joined the Department of Atmospheric and Oceanic Science at the University of Maryland, College Park and served as chair of the department. Along with James A. Yorke, she co-founded the Weather/Chaos Group at the University of Maryland, which has made discoveries of the local, low-dimensionality of unstable atmospheric regions and the development of the Local Ensemble Kalman filter and Local Ensemble Transform Kalman Filter data assimilation methods. In addition to the Atmospheric and Ocean Department, Kalnay has appointments in the Institute for Physical Science and Technology and the Center for Computational Science and Mathematical Modeling, also at the University of Maryland, College Park. In 2008, she was selected as the first Eugenia Brin Endowed Professorship in Data Assimilation. Among the scientific methods Kalnay has pioneered are the breeding method, which was introduced, along with Zoltan Toth, as a method to identify the growing perturbations in a dynamical system. She was also co-author on papers introducing the ensemble methods of Lag Averaged Forecasting and Scaled LAF. In 2017, Kalnay was part of an international team of distinguished scientists who published a study on climate change models in the National Science Review journal. The study argues that there are crucial components missing from current climate models that inform about environmental, climatic and economic policies. Kalnay observed that, without including the real feedbacks, predictions for coupled systems cannot work and the model can get away from reality very quickly.
