Relationship Between Atmospheric Rivers and Extreme Precipitation Events

Abstract

Extreme precipitation events cause notable socioeconomic impacts all over Europe. In the extreme cases 24 h precipitation amounts can exceed even average monthly amounts of precipitation, causing large floods in certain areas. In this study the relationship between extreme precipitation events and “Atmospheric rivers” will be investigated. Atmospheric rivers are narrow bands of high water vapor content and strong low level winds forming ahead of a cold front. Overlap of the atmospheric rivers with the favorable synoptic patterns usually leads to extreme amounts of precipitation, especially along western European coastal regions. In the extreme precipitation events the large-scale atmospheric patterns are analyzed using mean sea level pressure (MSLP) and geopotential height of the pressure level 500 hPa from the European Centre for Medium-Range Weather Forecast (ECMWF) analyses. For identifying the atmospheric rivers, ECMWF total column water vapor fields were used together with blended Total Precipitable Water product derived from the satellite measurements. The main goal of this study is to relate atmospheric rivers to local precipitation extremes, examine their potential as feeders of heavy precipitation, and to provide additional information for forecasting by summarizing the conditions leading to extreme precipitation events.