the role of a blocking systems on surface cyclogenesis over east of mediterranean sea and its influence on the mars 2000's flood over west of iran

abstract this research attempts to investigate the role of the blocking systems in surface cyclogenesis over eastern mediterranean sea; but particular attention is focused on the flood of iran during march 2000 over western states of iran as: hamadan, ilam, lorestan, kermanshah, kurdestan, zanjan, ghazvin.the data used for this research includes upper level and mean sea level pressure charts every 12 hours during 15 to 27 march 2000 from ncep center, also the data of temperature, pressure, humidity studied every 3 hours and data of daily precipitation totals studied from 19 important iran synoptic stations during 1 to 30 march 2000.results shows that: the trough in eastern flank of atlantic ocean blocking system was the main reason of march 2000 flood over iran; during blocking system activity in east of mediterranean sea, the splitting of jet stream has occurred near the second ridge over iran and it has intensified low pressure systems the near west of iran; the development of sudan low pressure system has caused enhance the intensity the eastern trough of blocking system and lead to flood over west of iran. keywords: blocking system; cyclogenesis; flood; jet stream; ridge.