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Study Investigates Convection Initiation Over the Eastern Arabian Peninsula

Climate change, growing population, and industrial and agricultural activities put an increased pressure on the water resources in the UAE due to its arid climate. Most of the water resources in the region are either directly or indirectly dependent on precipitation, and the groundwater resources are mainly recharged by the runoff of Al Hajar Mountains.

Although process studies have identified frequent convection initiation (CI) over the UAE region, there are no comprehensive statistics for CI events and their spatiotemporal variability. Towards this end, Dr. Volker Wulfmeyer, a First Cycle Awardee of UAE Rain Enhancement Program (UAEREP) and Managing Director and Chair of Physics and Meteorology at the Institute of Physics and Meteorology of the University of Hohenheim in Stuttgart, worked on a study that investigated summer statistics of CI events in the Al Hajar Mountains area spanning the eastern UAE and northern Oman, and covering a wide variety of topography, including coastal plains, mountains, and desert plains.

Using state-of-the-art satellite imagery, the study aimed to generate for the first time, spatially accurate CI statistics over the Al Hajar Mountains, based on a long time series of Meteosat-7 data, and to gain insights into regional climate and convective initiation mechanisms.

To validate the approach, Dr. Volker Wulfmeyer and his team investigated satellite datasets, alongside local C-band radar reflectivity data, for two convective cases in 2015. Subsequently, appropriate brightness temperature thresholds were used to identify deep convection and the preceding point of CI. Results showed that CI occurred most often just after local noon time (12:30 pm) closer to the highest central peaks and on the oceanic side of the Hajar ridge, with later events occurring further to the north, south and west. This diurnal progression was explained by the combination of a) primary convective cell outflows b) orographic geometry and differential heating, and c) the diurnal easterly sea breeze advection.

From their analysis, the team gained valuable insights into the regional climate and the mechanisms underlying convective storms over the Arabian Peninsula. The obtained CI statistics represent a new development for the UAE region and is set to significantly contribute to the ongoing cloud seeding operations with the ability to identify seedable clouds and categorize locations where they occur most frequently.

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