The Effects of Oman Sea Surface Temperature Anomalies in Autumn and Winter Precipitation of Southeast Coasts of Iran

The sea surface temperature (SST) variations play a very important role in the creation and maintenance of climatological and oceanographic processes such as heavy precipitation and subsequent floods, large-scale sea level fluctuations and tropical cyclones.In this paper the effects of Oman sea surface temperature (SST) on the autumn and winter precipitation of its northern coast, were investigated.The SST data was obtained from NCEP archives based on 4 points averaging nodes in Oman sea surface using GRADS software. Also the climatic data of 3 stations of Iranian coast (Chahbehar, Jask and Bandar Abas) were used.The warm (Rw), cold (Rc) and normal (Rb) periods of Oman SST were explained and the median of precipitations in each periods is calculated. The Rw\Rb, Rc\Rb and Rc\Rw ratios were used for evaluating the effects of these conditions on the precipitations anomalies on the coast.The results shown that the spring warm (cold) SST conditions in Oman sea can decrease (increase) precipitation in the selected stations of regions. Also the winter and autumn precipitation on northern coasts is remarkable, being synchronous to positive anomalies of summer SST.For considering the mechanism of the effect of Oman sea surface temperature on coastal precipitation, the stream lines, relative humidity and Omega maps were prepared and used. The results showed that the SST effects on stream lines and relative humidity on sea surface are the major mechanisms of precipitation anomalies. Generally during higher precipitation periods, the streamlines over the sea are navigate a longer route and therefore the moisture contents of rainfall systems and ascending currents are suitable for precipitation.