Observational analysis of a winter Shamal dust storm over the Middle East

Abstract: Dust storm formation in arid areas is a major global environmental problem as dust impacts regions close to the dust sources and can be transported far away for thousands of kilometers. The Middle East and Southwest Asia, which includes countries such as Iran, Iraq, Kuwait, and Saudi Arabia, are commonly affected by Shamal dust storms (mostly in summer) and frontal dust storms (in winter).

We use observations and reanalysis data to describe the formation and evolution of a winter shamal dust storm that occurred in February 2017. It initiated in central western Iraq and dust was transported southeastward towards the Persian Gulf, impacting all the countries in the region up to the Oman Sea.

The SEVIRI Dust RGB product shows dust mobilization at 07 UTC (10 LT) in several point areas west of the Euphrates River and over Mesopotamia, in Iraq. A dense dust plume is then advected in between the Zagros Mountains to the North and East and the high plains of Saudi Arabia to the South and West, reaching the Persian Gulf in the first hours of Febr. 18. Next day, dust spreads throughout the Persian Gulf and surrounding countries. The dust plume is well seen in the true color MODIS imagery of Febr. 17, 18, and 19. It resulted in the widespread reduction of horizontal visibility and impaired air quality, as reported by the region's Synop/METAR surface observations and air quality stations.

The large-scale upper-level processes leading to this event started days before with a strong amplification of an anticyclonic Rossby wave break in the Polar Jet over the North East Atlantic, with large penetration poleward of subtropical air up to Scandinavia and cold air advection equatorward over Iberia on February 11. At a late dissipative stage and downstream displacement, the RWB resulted in a closed ridge over southeastern Europe and a trough downstream over the study area. A strong pressure gradient was established at low levels between high pressures centered over Central Europe extending to the Black Sea and low pressures centered over Afghanistan/Pakistan and extending from the Oman Sea to western India. On Febr. 17, the location of the trough favored descent associated with transverse circulations on the upstream side of the trough over the mountains in eastern Turkey and northern Iraq, reinforcing the northerly winds imposed by the pressure gradient. On Febr. 17, strong downslope winds on the lee (southern) of the mountains in southern Turkey impacted the dust source areas in northern Iraq and Syria. Dust plumes were transported southeastward at heights below 2 km, as shown by CALIPSO profiles in Febr. 18, within the PBL. On Febr. 19, the dust plume was mixed all over the Persian Gulf basin.

Biography: I am Samira Karbasi. I was born in Tehran (Iran) in 1986.
I currently work as a postdoc researcher in the department of Applied Physics at Miguel Hernandez University of Elche in Spain, working as a WRF_Chem expert on multiscale processes related to dust mobilization and transport.
I got a BSc in Physics at Hormozgan University and hold a master and doctorate degree in meteorology in the Azad University of Tehran and Hormozgan university of Bandar Abbas, respectively. Due to my interest in air pollution and atmospheric compounds I wrote my doctoral dissertation on greenhouse gases, which are a major cause of climate change.