Despite rapid advances in numerical weather prediction (NWP) models and ever increasing computational capability, our ability to accurately predict various severe weather phenomena in the short range and at the mesoscales remains limited. This seminar talk will first present an overview of recent progress in our understanding of the mesoscale predictability of various severe weather phenomena including summertime squall lines, mesoscale convective systems, mesoscale convective vortices and tropical cyclones as well as wintertime snowstorms.
Through cloud-resolving simulations of the life cycles of the idealized baroclinic waves typical of developing midlatitude cyclones with strong baroclinic and conditionally instability, the second part of the talk will present a multistage error-growth conceptual model of mesoscale predictability. In the initial stage, the errors grow from small-scale convective instability and then quickly saturate at the convective scales. In the second stage, the character of the errors changes from that of convective-scale unbalanced motions to one more closely related to large-scale balanced motions. That is, some of the error from convective scales is retained in the balanced motions, while the rest is radiated away in the form of gravity waves. In the final stage, the large-scale (balanced) components of the errors grow with the background baroclinic instability. The chaotic nature of moist convection has a fundamental influence on the limit of mesoscale predictability.
Dr. Fuqing Zhang is a full professor with tenure in the Department of Meteorology at the Pennsylvania State University, with a joint appointment in the Department of Statistics. He also holds adjunct professorship appointment at Texas A&M University, Chinese Academy of Meteorological Sciences, and Nanjing University of Information and Technology in China. His research interests include atmospheric dynamics and predictability, data assimilation, ensemble forecasting, tropical cyclones, gravity waves, mountain-plains/sea-breeze circulations, warm-season convection, and regional-scale climate. He earned his B.S. and M.S. in meteorology from Nanjing University, China in 1991 and 1994, respectively, and his Ph.D. in atmospheric science in 2000 from North Carolina State University.
He spent seven years as an assistant and then associate professor at Texas A & M University before coming to Penn State in 2008. In 2000, he spent a year and a half as a postdoctoral fellow at the National Center for Atmospheric Research. Over the past few years during the summer and/or sabbatical leaves, he held various visiting scholarship appointments at various academic and research institutions including the Navy Research Laboratory in Monterey, California, the Chinese State Key Laboratory of Severe Weather in Beijing, China, Laboratoire de Meteorolgie Dynamique, École Normale Supérieure in Paris, France, and the National Center for Atmospheric Research in Boulder, Colorado.