Large-scale climatic influences on precipitation and discharge for a British river basin

This article aims to identify the large-scale climate variables that yield significant statistical relationships with precipitation and discharge for a British river basin (Dyfi). Ranked correlation analysis was performed between gridded ERA-40 atmospheric data and Dyfi precipitation and discharge for individual months. Precipitation and discharge demonstrate significant negative correlation with mean sea level pressure (MSLP). Strongest MSLP correlation areas move from north of Britain in winter to central Britain in summer; this shift is associated with a displacement of geopotential (Z) and zonal wind (U). Movement of significant correlation regions (not captured by the North Atlantic Oscillation Index) highlights the dynamic nature of precipitation and river flow generating weather systems throughout the year. Existence of strong significant correlation shows potential for exploiting large-scale climate variables in forecasting precipitation and river flow in Britain.