On the Effect of Red Sea and Topography on Rainfall over Saudi Arabia: Case Study

Al-Mutairi Al-Mutairi,Abdeldym Abdeldym,Morsy Morsy,Abdel Basset Abdel Basset

doi:10.3390/atmos10110669

Al-Mutairi Al-Mutairi, Abdeldym Abdeldym + Show 2 more

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https://doi.org/10.3390/atmos10110669

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Abstract

This paper aimed to investigate the impact of Red Sea topography and water on the development and rainfall of a case of cyclogenesis occurs over Saudi Arabia during the period 16–18 November 2015 using the Weather Research and Forecasting (WRF) model. The WRF Control Run (WRF-CR) experiment was performed with presence of actual topography and surface water of the Red Sea, while the other three sensitivity experiments were carried out without (i) Red Sea Topography (NRST), (ii) Red Sea Water (NRSW), and (iii) Red Sea Topography and Water (NRSTW). The simulated rainfall in the control experiment depicts in well agreement with Tropical Rainfall Measurement Mission (TRMM) rainfall estimates in terms of intensity as well as spatio-temporal distribution. Results demonstrate that rainfall intensity and spatio-temporal distribution significantly changes through each sensitivity experiment compared to the WRF-CR, where the significant variation was found in the NRST experiment. The absence of topography (NRST) leads to formation of strong convergence area over the middle of Red Sea which enhanced uplift motion that further strengthened the low-level jet over Red Sea and the surrounding regions, which enhanced the moisture and temperature gradient and created a conditionally unstable atmosphere that favored the development of the cyclonic system. The absence of Red Sea water (NRSW) changed rainfall spatial distribution and reduced its amount by about 30–40% due to affecting of the dynamics of the upward motion and moisture gradient, suggesting that surface fluxes play an important role in regulating the low-level moist air convergence prior to convection initiation and development.

Highlights

The east Mediterranean region is considered one of the most cyclogenetic areas in the world because of the surrounded mountains, orographic barriers, and arid regions, which interact with the air flow and play an important role in the formation of low-pressure centers [1]
Results demonstrate that rainfall intensity and spatio-temporal distribution significantly changes through each sensitivity experiment compared to the Weather Research and Forecasting (WRF)-CR, where the significant variation was found in the NRST experiment
The absence of topography (NRST) leads to formation of strong convergence area over the middle of Red Sea which enhanced uplift motion that further strengthened the low-level jet over Red Sea and the surrounding regions, which enhanced the moisture and temperature gradient and created a conditionally unstable atmosphere that favored the development of the cyclonic system

Summary

Introduction

The east Mediterranean region is considered one of the most cyclogenetic areas in the world because of the surrounded mountains, orographic barriers, and arid regions, which interact with the air flow and play an important role in the formation of low-pressure centers [1]. Saudi Arabia receives most of the precipitation during the period from November to April from synoptic-scale disturbances as a result of the invasion of the Red Sea Trough (RST) over the east Mediterranean, accompanied by warm and moist southern winds from tropical region [2]. The upper level middle latitude trough and the RST are the long-recognized cyclogenesis system developments over the east Mediterranean region [3]. The development of such cyclogenetic systems and rainstorms over. Numerical models provide a powerful tool for atmospheric research by performing sensitivity experiments. Their purpose is to isolate the effect of different factors on certain atmospheric fields in one or more case studies.

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