1. Global Climate Analysis
(1) Global climate change influence on rain fall
The tropical climate variability from the Indian and Pacific Oceans, viz. the Indian Ocean Dipole (IOD)
and the El Nino Southern Oscillation (ENSO), dominantly influence the rainfall patterns through the
atmospheric teleconnections. Besides, the changes in the Mediterranean Sea and the variabilities
originating from the extra-tropical regions are found to influence the rainfall anomalies of the Asir region.

Composite Precipitation Anm. Aug.-Sep. (All IOD) cm/month Composite Precipitation Anm. Aug.-Sep. (All ENSO) cm/monthh
50N
40N
30N
20N
10N
EQ
10S
20S
30S
40S
50S		 50N
40N
30N
20N
10N
EQ
10S
20S
30S
40S
50S

0 60E 120E 180 120W 60W

0 60E 120E 180 120W 60W
Composite Precipitation Anm. Aug.-Sep. (Pure IOD) Composite Precipitation Anm. Aug.-Sep. (Pure ENSO)
50N
40N
30N
20N
10N
EQ
10S
20S
30S
40S
50S		 50N
40N
30N
20N
10N
EQ
10S
20S
30S
40S
50S

0 60E 120E 180 120W 60W

0 60E 120E 180 120W 60W
Fig. 2　Relation of rainfall change in the world in relation with Indian Ocean Dipole(IOD)
　　　　　　and EI Nino Southern Oscillation (ENSO)

(2) Significant rainfall mechanism in Arabian region
The several significant rainfall events were identified using objective criterion for wide spread rainfall extending from Mecca region around 20°N to Basra region around 30°N (Table 1).



Table 1 Number of wintertime significant rainfall events over the Arabian region

199719981999
January7th,15th4th,5th8th,15th
Febuary-11th-
March5th,22th17th,29th28th



Fig. 3 Composites of time evolution of significant rainfall events (unit mm/day; contour interval is 2units) during January, where shaded region overlying contours of precipitation
DAY -1
DAY 0
DAY +1