الأنماط السينوبتيكية المصاحبة لأمطار المملكة العربية السعودية : الجزء الأول

الملخص EN

This paper aims to find and identify the synoptic patterns that associate rainfall over the Kingdom of Saudi Arabia (KSA) during the seasons of the year.

We studied the cases of rainfall (242 cases) that occurred during the period from 1997 to 2010.

the results revealed that there are 11 patterns ; these patterns were divided into five main groups.

In this paper (part 1) we studied and present the first and second groups.

the first pattern (A1) occurs when the presence of deepening upper air trough over the northern region of KSA meet with the inverted V-shape trough of the Sudan low that extended vertically from the surface to 850 hPa that causes rainfall over KSA regions.

the second one (A2) occurs due to the existence of deep midlatitude frontal cyclone over north of KSA and it join with the inverted V-shape Red Sea trough.

It is found that the pattern (B1) occurs when the formation of a convergence area over the central and southern part of the red sea from the surface to 850 hpa level where the trough of the sudan low exists over red sea with the presence of upper air trough.

the pattern (b2) occurs when the presence of upper air trough north of KSA and the surface dominated by the extension of the siberian high.

the maximum frequency of the pattern a and b occurs in winter season.