干旱区生态环境知识资源中心

Mediterranean cyclones, especially east cyclones of this sea, play a very important role in precipitation events of cold season in Iran. In the other hand formation of surface trough over the Red Sea makes possible the displacement of humidity from tropical area to extra-tropical area. To determine the role of Red Sea trough in supplying humidity sources of EM cyclones, surface data of geopotential height, specific humidity and Vertical and Horizontal component of wind in limited 5 through 65 degrees of north latitude and 0 through 80 degrees of east longitude were used. During the study 56 cyclones formed over the east of Mediterranean recognized which were simultaneous to the Red Sea troughs events. Convergence maps of moisture flux of 10 cases of simultaneous cyclones with Red sea trough which were strong, were drawn. Verification of convergence maps of moisture flux of selected cases show some required humidity for EM cyclones are initiated from Arabian Sea and then to some extent are reinforced over Persian Gulf and Gulf of Aden and then by passing over Red Sea enter to the south east of Mediterranean Sea. Actually Red Sea has not an important role in the humidity source of these cyclones and acts as a pass way for displacement of humidity of tropical area to extra-tropical area and injects the required humidity into the EM cyclones. To determine the regions-and-the amount of suction in the high levels, composite maps of ageostrophic divergence and jet streams of polar front were used.