The influence of large-scale atmospheric circulation weather types on variations in the water level of Lake Urmia, Iran

Lake Urmia, a large, hypersaline lake in north-western Iran, experiences large fluctuations in water level, and hence also surface area. At present, the water level is falling and the surface area contracting alarmingly. One important determinant of the water level of the lake is shown to be large-scale atmospheric circulation, expressed in terms of objective circulation weather types (CWTs), acting on the lake via regional precipitation and air temperature (as a proxy for evaporation). Seasonal changes in lake level, along with seasonal gridded precipitation and air temperature data, are shown to be strongly related to the frequency of occurrence of different CWTs. Copyright (c) 2011 Royal Meteorological Society