Synoptic analysis of the role of Saudi Arabia subtropical high pressure subtropical and polar jet streams and severe droughts in South and South West of Iran

Drought is a recurrent phenomenon in different climates. The occurrence of this phenomenon is not limited solely to the arid and semi-arid climates, but also occurs in climates humid and very wet. In this study, using data from annual precipitation 31 stations in the period (2015-1986), After complete homogeneity and process data deficiencies , the values of different profiles (SIAP, SPI, RAL, PNPI and Z Score) software in DIP and DIC were calculated and severe drought in the South and South West of Iran were identified. Required data received from the site http://www.esrl.noaa.gov and then in 1000 to 700 hPa levels synoptic maps outlining the core Saudi Arabia subtropical high pressure centers in the daily and monthly levels were above hPa. Synoptic analysis of data for drought pattern lengths ranging from -60 ° west to 100 ° east and latitude of zero (equator) to 80 ° north and software environment ARCGIS10.3 selected as the map was drawn. As well as the position of the jet stream in severe drought with script creation software and the core jet stream axis GRADS drawing and drawn. The dominant pattern of severe drought the region has been analyzed. The results showed that the severe drought in the region of the Azores anticyclone system tongues of four, Africa, Saudi Arabia and Siberian in a circuit line widths in the range of 15 to 45 ° north merged and for the entire region encompasses a wide belt. Saudi pressure quite moving West ward and throughout the period of precipitation on land is the Arabian Peninsula and integration with high pressure tripped Africa pushing low pressure Sudan to prevent its spread to the southern latitudes and high latitudes is and moves West ward cell with Saudi, Subtropical jet stream has moved West ward and the North East Africa