Non-Stationarity of the Spatial Footprints of Storm Surges

Storm surges can cause extreme coastal flooding across large and sometimes geographically disconnected areas. Understanding their spatial footprints is essential for effective risk assessment and emergency planning. Previous studies have delineated the spatial footprints of extreme storm surges at global and regional scales, assuming that they remain stationary over time. This study investigates the temporal variability of storm surge spatial footprints along the U.S. East Coast, the Gulf, and the Caribbean Sea. Our results show that spatial footprints are seasonally dependent, with tropical cyclone and extratropical cyclone seasons producing distinct patterns of coastal connectivity. Interannual variability in the size of the storm footprints is also evident, with anomalously large footprints coinciding with strong La Niña phases and during transition years from El Niño to La Niña, particularly in the Caribbean Sea. Decadal analysis reveals relatively minor variations, while seasonal patterns persist over decadal time periods.