Tropical Moisture Exports, Extreme Precipitation and Floods in Northeastern US

Abstract

A statistically and physically based framework is put forward to investigate the relationship between Tropical Moisture Exports (TMEs), extreme precipitation and floods in the Northeastern United States (NE-US). We found that the NE-US floods in the four seasons are closely related to TMEs and four major moisture sources of TMEs in the tropics account for approximately 85% of all the TMEs that enter the NE-US. The seasonality and interannual variation of the birth processes in the four source regions determine their contribution to the NE-US. Moisture born in Gulf of Mexico (GP) and Gulf stream (GS) are the year-around sources, with some winter contribution from Pineapple Express (PE) region, and West Pacific (WP) region contributes the least. The overall order of their contribution to NE-US is GP>GS>PE>WP. Seasonal association between TMEs birth and ENSO are also found. The seasonal and interannual variations in atmospheric circulation patterns also play an important role in determining the TMEs’ entrance to NE-US. Strong influence of active TMEs periods on the occurrence of extreme rainfall is also identified. We show that the extreme daily precipitation events are dominated by extreme TMEs’ entering the NE-US in every season.