Department of Earth Sciences Seminar Series McInerney Lecture

1. Department of Earth Sciences Seminar SeriesMcInerney Lecture Snow Cover Ablation, Synoptic Weather Types and Winter Season Chesapeake Bay Hydrology Dr. Daniel Leathers Deputy Dean College of Earth, Ocean, and Environment University of Delaware Newark, DE 19716 Where: Caputo 210; Armstrong Auditorium When: 4:00 PM social in the Caputo Lobby 4:30 PM Seminar Begins Abstract The Chesapeake Bay is the United States largest estuary and a highly productive ecosystem that is maintained through nutrient influx from six states. Snow cover ablation is an important component of the hydrologic system across the Chesapeake Bay drainage basin as the magnitude or rate of snow cover ablation can have major implications for flooding and excess nutrient fluxes. In order to identify the synoptic weather patterns that are associated with snow cover ablation across the region, a modified version of the Temporal Synoptic Index (TSI) is used to classify distinct synoptic weather types for Philadelphia, Pennsylvania for the period 1946 through 2007.  The TSI identifies 13 winter (DJF) and 13 spring (MAM) weather types that characterize the snow season climate of the Chesapeake Bay drainage basin. Using a daily gridded snow cover product and hydrologic data from the Bay’s major tributaries, major ablation and flooding events are identified and the role of diverse synoptic weather types in these events are characterized. Time series of the frequency of the synoptic weather types for the period show substantial interannual variability and/or trend, depending upon the specific weather pattern considered.  An analysis of the relationship between the weather type frequencies, Chesapeake Bay flooding events and low-frequency atmospheric forcing mechanisms (NAO, PNA, ENSO, etc.) is presented. THURSDAY: 22nd, April, 22nd, 2010