资源环境科技发展态势分析平台

The eastern United States is extremely vulnerable to Atlantic basin tropical cyclones (TCs) and their associated precipitation. While many studies have focused on the magnitude or contribution of tropical cyclone precipitation (TCP) to overall rainfall, there is a need for a detailed climatology of spatial characteristics of inland TCP extent for this region. In this study, we develop a Geographic Information System method to delineate rainfall swaths for 257 US landfalling TCs during 1948 to 2014 using a daily gridded dataset. We then describe spatial patterns of TCP using three methods. First, we measure the rainfall swath areas and average widths over land, and find that TCs that spend longer periods over land have wider average widths so that rainfall swaths cover larger areas. Second, trends in the change of left extent of TCP swaths are analysed and TC attributes related to these trends are explored. Seventy of 85 TCs have rain swaths that expand on the left side at some points as they move inland. The TCs exhibiting expansion were hurricanes at landfall, re-intensifying over land, undergoing extratropical transition, and/or moving near the coastline. Last, we construct a series of maps with return intervals and frequency distributions for inland TCP and tropical storm-force winds. The results show that 94% of 2435 counties over the eastern United States are more frequently exposed to rainfall than wind from TCs. While cumulative rainfall shows a gradual decrease from southeastern coast inland, many inland regions have received five to six TCP events in a single season, which confirms that TCP should be a concern for people living inland as well as near the coast. This study's analysis of the spatial characteristics of TCP inland extent from a climatological perspective should benefit forecasting, hazard mitigation, and risk analysis of TC hazards.