Publication Date:
2012-04-15
Description:
The statistical relationships among the various 10°–70°E mid-latitude blocking anticyclone parameters and the weather of the Arabian Peninsula (AP) (35°–60°E, 12°–32°N) over a 40-year period (1968-2007), on seasonal, interannual, decadal and long-term scales, are studied. The studied parameters include the number of blocking anticyclone events, the duration, the intensity, and the longitude at the blocking anticyclone onset. It is found that 31% of the Northern Hemisphere mid-latitude blocking anticyclone events occurred over the 10°–70°E longitudes, and out of these, the maximum number of mid-latitude blocking anticyclone event onsets are at 30°E (24%). On the seasonal basis, the annual and decadal relationships of the 10°–70° blocking anticyclones with the El-Niño Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO) indices are presented. The results show that the number of days the blocking anticyclones persists is sensitive to the ENSO phase. The mid-latitude blocking anticyclone occurrence over the 10°–70°E longitudes is indicative of the reduced surface temperature variance, both upstream and downstream, during the blocking anticyclone period, over the AP. A shift in the mean surface temperature distribution occurs, in all seasons, during the blocking anticyclone period. The blocking anticyclones initiate a surface temperature change (both positive and negative) that persists even after the blocking anticyclone's decay. The AP surface weather during the months of October, November, and December is affected more by the occurrence of mid-latitude blocking anticyclones over the 10°–70°E longitudes in the presence the of El-Niño phase. Copyright © 2012 Royal Meteorological Society
Print ISSN:
0899-8418
Electronic ISSN:
1097-0088
Topics:
Geosciences
,
Physics
