Investigation of Atmospheric Conditions Associated with a Storm Surge in the South-West of Iran

Esmaeil Abbasi,Joseph M Smoak,Jaromir Krzyszczak,Iman Rousta,Haraldur Olafsson,Hana Etemadi,Piotr Baranowski

doi:10.3390/atmos12111429

Abstract

Severe thunderstorms are often accompanied by strong vertical air currents, temporary wind gusts, and heavy rainfall. The development of this atmospheric phenomenon over tropical shallow water zones, such as bays, can lead to intensification of atmospheric disturbances and produce a small-scale storm surge. Here, the storm surge that occurred on 19 March 2017 in the Persian Gulf coastal area has been investigated. Air temperature, precipitation, mean sea level pressure, wave height, wind direction, wind speed, geopotential height, zonal components, meridional winds, vertical velocity, relative humidity, and specific humidity obtained from the European Centre for Medium-Range Weather Forecasts (ECMWF) and Global Forecast System (FNL) were used to implement the Weather Research and Forecasting (WRF) model. The results showed that the main cause of the storm surge was the occurrence of a supercell thunderstorm over the Persian Gulf. The formation of this destructive phenomenon resulted from a downburst under Cumulonimbus cloud and high-velocity air subsidence, after collision with the sea surface coinciding with the high tide. This caused a severe, yet temporary, gust, which in turn caused the creation of the four waves of 3.1 m height along the coast of Bandar Dayyer.

Highlights

Variations in atmospheric pressure are responsible for fluctuations in sea level, with high-pressure areas reducing the level of water, and low-pressure areas raising it
Winds that initiate a storm surge cannot be created by a downburst, whereas a storm surge may appear in regions with highly elevated water levels [6]
To investigate the overall state of the atmosphere, firstly the weather maps extracted from European Centre for Medium-Range Weather Forecasts (ECMWF) data were examined, and a more detailed analysis of the atmosphere in the studied area using the Weather Research and Forecasting (WRF) model was performed and the outputs from it were analyzed

Summary

Introduction

Variations in atmospheric pressure are responsible for fluctuations in sea level, with high-pressure areas reducing the level of water, and low-pressure areas raising it. Since the effect of pressure is relatively small, surges are mainly driven by wind stress, especially over shallow water in coastal areas [4]. The water level is influenced by pressure gradients, they have a less direct effect on creating a storm surge, especially in shallow water areas [5]. Winds that initiate a storm surge cannot be created by a downburst, whereas a storm surge may appear in regions with highly elevated water levels [6]. In such conditions, precipitation and cooling during the micro-physical processes cause the movement and acceleration of downdraft airflow

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