Authors: H M Hasanean H Abdel Basset M A A Hussein
Publish Date: 2015/03/05
Volume: 32, Issue: 5, Pages: 690-703
Abstract
The synoptic circulation over Saudi Arabia is complicated and frequently governed by the effect of largescale pressure systems In this work we used NCEPNCAR global data to illustrate the relationship between climatic variables and the main pressure systems that affect the weather and climate of Saudi Arabia and also to investigate the influence of these pressure systems on surface air temperature SAT and rainfall over the region in the winter season It was found that there are two primary patterns of pressure that influence the weather and climate of Saudi Arabia The first occurs in cases of a strengthening Subtropical High SubH a weakening Siberian High SibH a deepening of the Icelandic Low IceL or a weakening of the Sudanese Low SudL During this pattern the SubH combines with the SibH and an obvious increase of sea level pressure SLP occurs over southern European the Mediterranean North Africa and the Middle East This belt of high pressure prevents interaction between midlatitude and extratropical systems which leads to a decrease in the SAT relative humidity RH and rainfall over Saudi Arabia The second pattern occurs in association with a weakening of the SubH a strengthening of the SibH a weakening of the IceL or a deepening of the SudL The pattern arising in this case leads to an interaction between two different air masses the first cold moist air mass is associated with the Mediterranean depression travelling from west to east while the second warm moist air mass is associated with the northward oscillation of the SudL and its inverted Vshape trough The interaction between these two air masses increases the SAT RH and the probability of rainfall over Saudi Arabia especially over the northwest and northeast regions
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