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Document Type |
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Thesis |
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Document Title |
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Diagnostic study of a severe thunderstorm over Jeddah during hajj 1430 H دراسة تشخيصية لعاصفة رعدية قوية على مدينة جدة لحج عام 1430هـ |
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Subject |
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Department of Meteorology |
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Document Language |
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Arabic |
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Abstract |
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Cyclones and anticyclones are the dominant synoptic scale meteorological weather systems in midlatitude and subtropical areas. An attractive way to study dynamical aspects of these structures is provided by the use of potential vorticity (PV) framework. In this thesis several aspects of the interaction between midlatitude and subtropical systems are investigated within this PV framework using a case study analyses. Our case study occurs on 25 November, where Jeddah, Makkah, Rabigh and other regions in Western Saudi Arabia, were hit by heavy rainstorms. The impact of the severe convective weather process caused more than 90 millimeters of rain to fall in Jeddah in just four hours.
The analysis of isobaric absolute and relative vorticity and the isobaric potential vorticity will be used to imply the significance of the upper level dynamics in the initiation of this case of cyclogenesis. On one hand, the isobaric vorticity analysis appears to be an informative, accurate and easy to use as a method for describing the upper-level dynamics. On the other hand the PV analysis provided a summarized picture of the development and the evolution at upper and lower levels, which is directly visible, on the basis of a smaller number of plots compared with the isobaric vorticity analysis. The display of the time sequence of the PV on the appropriate isobaric surface helped in easily understanding the dynamics of the three-dimensional upper level development. The PV analysis also identified possible diabatic effects at low levels in the area of eastern Red sea, an area where the diabatic processes appear to play an important role in cyclonic development. The most significant finding from the analysis of our case show that: (1) An upper level cold trough in the Eastern Mediterranean moves from west to east, and a warm blocking high is situated on the southeast Saudi Arabia and Arabian Sea. In addition, an evident low level shear line set up in the northwest of Jeddah, and the southeast movement of the shear line caused dynamic lifting and unstable energy release over Jeddah. (2) The water vapor transport mainly happened below 700hPa, and low-level jet transports the water vapor from the Red Sea to Saudi central. Furthermore, the blocking high in southern Saudi Arabia is favorable for maintaining water vapor passage for a long time. (4) Jeddah lies in the coastal plain of the Red Sea, bordered by the Hijaz plateau on the east. Topography also has played a role in the enhancement of convection. Finally, in the end of our severe thunderstorm case study we trace the rainfall of this situation by radar and examine the relationship between the estimated rainfall by radar and rain measured on the surface of the earth. |
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Supervisor |
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Prof. Abdurrahman K. Al Khalaf |
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Thesis Type |
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Master Thesis |
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Publishing Year |
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1433 AH
2012 AD |
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Co-Supervisor |
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Prof. Heshmat A. Mohamed |
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Added Date |
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Saturday, April 14, 2012 |
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Researchers
| أيمن محمد البار | Albar, Ayman Mohammed | Researcher | Master | |
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