School of Meteorology (Defense)
Modulation of tropical cyclone activity by El Niño in a warming environment
School of Earth and Atmospheric Science
Georgia Institute of Technology
20 April 2012, 3:00 PM
National Weather Center, Room 1350
120 David L. Boren Blvd.
University of Oklahoma
Pacific Ocean warming (El Niño) has been separated into two modes based on the spatial distribution of the maximum sea surface temperature anomaly: an East Pacific Warming (EPW) and a central Pacific Warming (CPW). Two regimes are shown to have different impacts on the frequency and tracks of tropical cyclones (TC) over the North Pacific and North Atlantic by differential modulation of both local thermodynamic factors and large-scale circulation patterns. In North Atlantic, CPW episodes are associated with a greater than average frequency and increasing landfall potential along the Gulf of Mexico coast and Central America. Differences are shown to be associated with the modulation of vertical wind shear in the main development region forced by differential teleconnection patterns emanating from the Pacific. In North Pacific, TC activity is shifted to the west and is extended through the northwestern part of the western Pacific. The westward shifting of CPW-induced heating moves the anomalous westerly wind and monsoon trough through the northwestern part of the western Pacific and provides a more favorable condition for TC landfall. Since 1990, CPW events have become more prevalent and that there is a greater and earlier predictability of a CPW event than an EPW event, potentially increasing the predictability of cyclones on seasonal time scales.