Abstract:
Tropical cyclones (TCs) can generate costly hazards, and their coastal activities are particularly significant to our society. This talk will focus on the historical observations and simulations of coastal TC activities. First, I will present an analysis of the global mean change in TC frequency in coastal offshore regions based on observations. I will demonstrate that there has been a robust migration of TC activity toward the coasts, with an increase of two additional TCs per decade in global coastal offshore regions. Second, I will use large-ensemble TC-permitting simulations to show that the observed changes in global coastal TC frequency since 1980 were driven by anthropogenic greenhouse gases (GHG) and/or aerosols. Specifically, the observed increases in TC frequency near the US Atlantic coast and Hawaii are likely associated with aerosol and GHG effects, respectively. The observed decrease in the South China Sea could be attributed to GHG emissions alone, while the increase near Japan and Korea appears to be linked to the combined effects of aerosols and GHGs. These changes can be explained by the responses of large-scale environmental conditions to anthropogenic forcing.