Document Details
|
Document Type |
: |
Thesis |
|
Document Title |
: |
INFLUENCE OF MID-LATITUDE AND GLOBAL CIRCULATIONS ON THE ARABIAN PENINSULA SUMMER TEMPERATURE تأثير الأنظمة الحركية في العروض الوسطى والعالمية لدرجة حرارة الصيف على شبه الجزيرة العربية |
|
Subject |
: |
Faculty of Meteorology, Environment and Arid Land Agriculture |
|
Document Language |
: |
Arabic |
|
Abstract |
: |
Surface air temperature (SAT), particularly in summer (June-Aug), is an important climate parameter for the Arabian Peninsula, a very semi-arid to arid region in the Northern Hemisphere (NH). The extreme temperature events (ETEs) over the region, particularly over Saudi Arabia, have been receiving special attention in recent decades due to their potential impacts on water resources, the power sector, human health and crop yield. In this thesis the summer SAT over the Arabian Peninsula and the associated global circulations particularly the mid-latitude circulations are analyzed. For the regional temperature analyses, the summer season daily maximum temperature (Tmax) data were obtained from 27 meteorological stations for the period 1981-2017 around Saudi Arabia (which accounts for 80% of the Peninsula area).
Frequency analysis revealed that the stations located in the Central, Northern and the Coastal regions experience a relatively higher number of ETEs during the summer season. A composite analysis was performed to explore the associated global circulations with ETEs over Saudi Arabia. It is found that the summer ETEs over Saudi Arabia are associated with the mid-latitude circumglobal wavelike (CGT) pattern. The upper level circulations associated with the ETEs over different regions of Saudi Arabia range from a weak mid-latitude CGT wave pattern (e.g., associated with coastal region ETEs) to well-developed CGT patterns (e.g., associated with central region ETEs). The upper level anomalous high (low) pressure over Eurasia (Central Asia), coupled with anomalous low (high) pressure at the surface, directs the hot and dry air from desert regions that favours the occurrence of ETEs in different regions of Saudi Arabia. A lead-lag relationship between 200 hPa geopotential height and ETEs over central parts of Saudi Arabia reveals strong association between mid-latitude circulation and ETEs over Saudi Arabia.
Moreover, an inverse relation between Tmax over Saudi Arabia and the El Nino Southern Oscillation (ENSO) is also found. ENSO modulates the regional Tmax anomalies through the upper level mid-latitude CGT. To further explore the role of ENSO and the mid-latitude wave train CGT in controlling the interannual variability of SAT over the Arabian Peninsula, the long term Climate Research Unit (CRU) dataset over the region is analyzed for the period 1951-2015. A strengthening in the relationship between El Nino Southern Oscillation (ENSO) and summer SAT over the Arabian Peninsula in recent decades was found. This relationship was weak before the 1980s. The upper level circulation patterns associated with ENSO resemble the CGT pattern. The warm phases of ENSO over the central and eastern Pacific are associated with anomalous low pressure over the Eurasian region, which favours above-normal SAT anomalies over Eurasia, including the northern parts of the Peninsula. Conversely, the cold phase of ENSO is associated with anomalous high-pressure pressure and below-normal SAT anomalies over southern Eurasia. The weakening of upper level geopotential height anomalies over central Asia during the positive phase of CGT also favours the extension of the Eurasian high over the Arabian Peninsula. Additionally, the climate model simulation experiments performed with the newly developed Saudi-KAU Atmospheric Global Climate Model (AGCM) also support the observed findings. |
|
Supervisor |
: |
Prof. Mansour Almazroui |
|
Thesis Type |
: |
Doctorate Thesis |
|
Publishing Year |
: |
1440 AH
2019 AD |
|
Added Date |
: |
Wednesday, July 31, 2019 |
|
Researchers
| عرفان الرشيد | ALRashid, Irfan | Researcher | Doctorate | |
|
Back To Researches Page
|