in this research, the correlation between precipitation change in southern coasts of caspian sea and variability of sea level pressure have been analyzed by using environmental to circulation approach at time period 1339- 1383. in this respect, we make use of daily precipitation data of the 12 synoptic stations of studied area at surface data base section and prepare the time series matrix of p...

1. introduction the position of iran in the subtropical region that has made its arid and semiarid climate and the topographic diversity changes this trend of climate. therefore, climate hazards such as frost, flood, dust storm, drought, temperature anomalies, heavy rainfall, avalanches, snow, sleet, etc occur in iran. the northwest of iran experiences the above conditions following the arrival...

in the current attempt, the relation between precipitation change in southern coasts of iran and sea level pressure data of ncep / ncar database were investigated through correlation method using environment to circulation approach in the period of 1960-2004. after calculating the correlation matrix between the percipitation amount and pressure, the precipitation-pressure correlation map for ea...

introduction although temperatures in 0 and below 0 c° in the cold season of the year and mid latitudes are not necessarily considered an extreme phenomenon, but their long-term durability in a widespread area or their sudden occurrence in the beginning and end of the cold season can make this faetor an extreme extent phenomenon. the extreme phenomena are resulted from interaction between large...

the areas of the world that have mediterranean style climate are found at about 35 degrees north and south of the equator, on the western sides of continents. the distinctive feature of this climate is the small amount of rain in the summer. overall, the climate has a moderate amount of rainfall and warm winters and hot summers and. the climate of the mediterranean region is conditioned by its ...

introductionmany aspect strongly influence regional climate includes localized surface processes, large-scale patterns, especially mid and upper level tropospheric circulation and many factors control precipitation in the west of iran includes location of emigrate westerly winds systems, jet streams location, humidity flux and topography. upper tropospheric jet stream constitutes a significant ...

1. introduction heavy snow hazards, although have less frequency in comparison with extreme weather events such as freezing, but are major hazards in midlatitudes (smith, 2009, 196). heavy snow damages manmade structures, crops, casualties, even between urban and rural ways of blocking.(briant. 69, 2005. ohara et al, 2009, 1611). various definitions have been offered for heavy snow, those are c...