Atmospheric Dynamics and Numerical Simulations of Six Frontal Dust Storms in the Middle East Region

Nasim Hossein Hamzeh,Dimitris G Kaskaoutis,Sara Karami,Ina Tegen,Mohamad Moradi,Christian Opp

doi:10.3390/atmos12010125

Abstract

This study analyzes six frontal dust storms in the Middle East during the cold period (October–March), aiming to examine the atmospheric circulation patterns and force dynamics that triggered the fronts and the associated (pre- or post-frontal) dust storms. Cold troughs mostly located over Turkey, Syria and north Iraq played a major role in the front propagation at the surface, while cyclonic conditions and strong winds facilitated the dust storms. The presence of an upper-atmosphere (300 hPa) sub-tropical jet stream traversing from Egypt to Iran constitutes also a dynamic force accompanying the frontal dust storms. Moderate-Resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) observations are used to monitor the spatial and vertical extent of the dust storms, while model (Weather Research and Forecasting model coupled with Chemistry (WRF-Chem), Copernicus Atmospheric Monitoring Service (CAMS), Regional Climate Model-4 (RegCM4)) simulations are also analyzed. The WRF-Chem outputs were in better agreement with the MODIS observations compared to those of CAMS and RegCM4. The fronts were identified by WRF-Chem simulations via gradients in the potential temperature and sudden changes of wind direction in vertical cross-sections. Overall, the uncertainties in the simulations and the remarkable differences between the model outputs indicate that modelling of dust storms in the Middle East is really challenging due to the complex terrain, incorrect representation of the dust sources and soil/surface characteristics, and uncertainties in simulating the wind speed/direction and meteorological dynamics. Given the potential threat by dust storms, more attention should be directed to the dust model development in this region.

Highlights

Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) overpasses over the region— a delay exists between Moderate-Resolution Imaging Spectroradiometer (MODIS) and CALIPSO observations—while a direct comparison between
CALIPSO orbit paths are shown by the red lines in MODIS imagery, with the arrows denoting the direction of the overpass, while the presence of the thick dust plumes is highlighted by the circle and oval shapes in the MODIS and CALIPSO images
According to CALIPSO profiles, this dust storm was traveling from Mesopotamia towards the eastern Arabian Peninsula in the lower troposphere (

Summary

Introduction

Desert dust is a major constituent of the Earth’s atmosphere and the second most abundant aerosol type. Emitted from desert areas mainly in the Northern Hemisphere, dust storms are considered as natural hazards with deleterious effects on climate, human health, marine and terrestrial ecosystems [1,2,3]. Investigation of dust storms is very important in countries located in the global dust belt or directly affected by transported dust plumes [4,5,6,7]. The Middle East region contributes around 15–20% to the global dust emissions, with origin mostly from the deserts in the Arabian Peninsula, Iraqi plains and southeast Iran [8,9,10]. Dust storms originating from the Middle East and the Arabian

Objectives

Results

Conclusion