World Teleconnection and Regional Teleconnections of Iran

Teleconnection is defined as a meaningful relationship of time variations of two meteorological patterns that are far from each other and teleconnection is an important principle in climate for the explanation of meterologic phenomena. The term was used for the first time in climate studies by Angstrom (1935). Later Wallace and Gautzler (1981) defined the concept as a meaningful correlation between the time series of a month or longer of the climate parameters in distant locations. Teleconnections are associated with the anomaly of atmospheric large scale and hemisphere circulation. Therefore, it is important to recognize teleconnections affecting the regional climate. In this regard the question is: What are the most important global teleconnections for the cold seasons in Iran? To find an appropriate answer, the monthly time series of teleconnections close to Iran and the world from 1950 to 2010 were selected and the Pearson correlation method was used. The correlations indicated that global phenomena associated with regional teleconnection are established in the North Atlantic, Europe and Western Siberia, while the Pacific Oceanographic centers have a weak connection with the regional teleconnection in the cold period. The most important phenomena in the middle layers of the atmosphere are the North Sea - Caspian Pattern (NCP), and the North Atlantic Oscillation (NAO) associated with regional teleconnection of the Western Europe - North Caspian. In the positive phase of the North Atlantic Oscillation and the North Sea - Caspian Pattern, the precipitation increases and the temperature decreases while in the negative phase, the temperature increases and precipitation decreases in Iran. These two phenomena are important and reliable predictors in Iran. At ground level, the Arctic Oscillation (AO), Scandinavia (SCAND), Eastern Atlantic - Western Russia (EA-WR) and East Atlantic (EA) related to regional teleconnection of Northern Europe, Northern Siberia, and Central Asia are the most important phenomena on the surface for the climate of Iran. In the negative phase of the Arctic Oscillation, Scandinavia, the precipitation increases and temperature decreases for the climate of Iran, and in the positive phase of these two, the climate of Iran experiences dries conditions. Also in the positive phase of the Eastern Atlantic and Eastern Atlantic - western Russia, the temperature decreases and the precipitation increases, and in the negative phase, the temperature increases and the precipitation decreases. It appears the global and regional teleconnections in Eurasia and the Northern Atlantic are not completely separated. Therefore, the global teleconnection associated with the climate of Iran are: the North Atlantic Oscillation, the North Sea - Caspian Pattern, Arctic Oscillation, Scandinavia, Eastern Atlantic - Western Russia and Eastern Atlantic. Often, teleconnections of the cold seasons of Iran are related to meridional westerlies along the blocking and cut-off low that are established in Western Europe, Central and Western Siberia to lower and higher latitudes in the same geographic locations. In climate studies one should not ignore the role of geographic featues on the surface of the earth, while considering the above-mentioned issue.