Changes of Precipitation Regime of the Iranian Coast of Caspian Sea (ICCS)

Abstract

In the current study, the daily data of 385 stations under Meteorological Organization and the Ministry of Energy's supervision have been used for the period of 2016-1966. Precipitation regime and its changes of the Iranian Coast of Caspian Sea (ICCS) were studied. At first these stations are used in order to create maps with a spatial resolution of 3 × 3 km and the general characteristics of the monthly and annual precipitation. Then, to determine the precipitation regime and its changes, the seasonal index of precipitation was studied for the whole under investigation period and also the seasonal indices were estimated for the previous five decades. The seasonal precipitation index of the ICCS indicates three types of precipitation regime. The results of the study of the changes in the ICCS's precipitation regime over the last five decades indicate that the lowest spatial extent of the precipitation regime is related to a "Very equable" regime. The area under this regime, except in the fourth decade (1995-2005), has been significantly reduced. The mainly seasonal regime is seen "Rather seasonal with a short drier season", on the coastline of the Caspian Sea, parts of the Talesh heights and parts of the eastern region. It is worth noting that the modest changes in this regime are in the eastern part of the region. In general, it can be said that this periodic diet has a fluctuation behavior of decrease, increase, decrease, increase, respectively

Keywords

• precipitation regime
• precipitation regime change
• seasonal index
• caspian region