28Feb 2015

The synoptic features of the autumn dust classes in Northern Saudi Arabia

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Three classes of autumn dust (narrow, moderate and widespread) have been identified over northern Saudi Arabia and were classified according to the values and spread of the Aerosol Index (AI) obtained from the TOMS satellite. Furthermore, the synoptic features that distinguish these classes were studied using NCAR/NCEP reanalysis data. Additionally, the frequency of the dust types observed on the surface accompanying these classes have been studied, and it has been demonstrated that Blowing Dust is the most frequent type, while the dust/sand storms occur with lesser frequency throughout autumn. This synoptic study of the various classes of dust demonstrated the importance of the Azores and Siberian highs and the Indian low regarding the autumn dust over the northern Arabian Peninsula and also showed that the relative inter-position and the strength of these cyclonic and anticyclonic systems play an important role in the occurrence and intensity of the various classes of dust. Moreover, the study showed that the intensity of the vertical motion, the decrease of the static stability over the Arabian Peninsula and its increase over the Mediterranean and Arabian Seas, in addition to the northern shift of the atmospheric systems at 500 hPa, are the main factors affecting the strength of the dust cases. This synoptic study of the various classes of dust demonstrated the importance of the Azores and Siberian highs and the Indian low regarding the autumn dust over the northern Arabian Peninsula and also showed that the relative inter-position and the strength of these cyclonic and anticyclonic systems play an important role in the occurrence and intensity of the various classes of dust. Moreover, the study showed that the intensity of the vertical motion, the decrease of the static stability over the Arabian Peninsula and its increase over the Mediterranean and Arabian Seas, in addition to the northern shift of the atmospheric systems at 500 hPa, are the main factors affecting the strength of the dust cases.


[Abdul-Wahab Mashat and Adel Awad (2015); The synoptic features of the autumn dust classes in Northern Saudi Arabia Int. J. of Adv. Res. 3 (2). 0] (ISSN 2320-5407). www.journalijar.com


Adel M Awad


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