Climatology and the dynamic mechanism of the Levar wind and dust events in eastern Iran

• Published in: International journal of climatology 2022-12, Vol.42 (16), p.9288-9303
• Main Authors: Alizadeh, Omid, Abniki, Marzieh, Babaei, Morteza, Irannejad, Parviz
• Format: Article
• Language: English
• Subjects: Atmospheric particulates; Climate; Climate change; Climate models; climatic change; Climatology; Dry deposition; Dust; Dust emission; dust events; Dust particles; Dust storms; eastern Iran; Emission; Emissions; High pressure; Levar wind; Low pressure; Mathematical models; Numerical models; Pressure; Pressure gradients; RegCM4; Regional climate models; Regional climates; Seasonal variations; Seasonality; Storms; Strong winds; Surface wind; Western Afghanistan; Wind; Wind speed; Winds
• ISSN: 0899-8418; 1097-0088
• DOI: 10.1002/joc.7818

Dust storms in eastern Iran have a wide range of socioeconomic impacts, yet long‐term numerical model analysis of the mechanism of strong winds and dust events in this region is limited. The regional climate model version 4 (RegCM4) coupled with a dust module is used to understand the climatology, climatic change, and the dynamic mechanism of the Levar wind and dust events in eastern Iran for the period 1991–2017. It is found that the strong Levar wind is the main driver of dust events in eastern Iran, particularly from June to September. Both model simulation and observations indicate that the Levar wind is strongest on the border between South Khorasan Province in Iran and Afghanistan. Our analysis indicates that the Levar wind is caused by the development of anomalous surface high pressure in Central Asia extending toward northeastern Iran and anomalous surface low pressure on the border between western Afghanistan and Pakistan. The strong pressure gradient force associated with these anomalous high‐ and low‐pressure systems is responsible for the strong northerly Levar wind on the border between Iran and Afghanistan. Dust activity in eastern Iran exhibits a distinct seasonality. The highest dust emission occurs on the border between eastern South Khorasan Province in Iran and western Afghanistan from June to September, where near‐surface winds are also the strongest. Relatively less dust emission occurs in dry beds of Jazmourian from June to September, south of Saravan in May, and Rig‐e Yalan in June. The removal of dust particles from the atmosphere is mainly by dry deposition in eastern Iran. The main sink of dust is located in the western parts of the Sistan Basin. Dust emission and burden in the main source of dust in eastern Iran have significantly decreased during the period 1991–2017, while near‐surface wind speed has remained nearly unchanged. The Levar is caused by the development of anomalous high pressure in Central Asia and anomalous low pressure on the western border of Afghanistan and Pakistan. A distinct seasonal pattern of dust activity is identified in eastern Iran. Dust emission and burden in the main source of dust in eastern Iran have significantly decreased during the period 1991–2017, while near‐surface wind speed has remained nearly unchanged