Interannual variations of dust activity in western Iran and their possible mechanisms

Abstract

Through an analysis of station observations and reanalysis data, in this study, we investigate the variations of dust activity during 1979-2015 in western and southwestern Iran and their associated mechanisms. The dust day frequency (DDF) is used to identify dust activities. The results show larger interannual variabilities in the DDF in spring and summer, with standard deviations (σ) of 10% and 13%, respectively. Correlation analyses reveal that the interannual variability of DDF in western Iran is largely regulated by wind speed, precipitation and soil moisture in the region. The regional mean spring (March-May) DDF shows strong negative correlations with spring precipitation (correlation coefficient R = −0.5) and soil moisture (R = −0.6) over western to southwestern Iran, but strong positive correlations between the springtime DDF and surface winds can be found with the R reaching 0.4-0.6. Dust activity in the summer dry season (June-August) is mainly associated with surface winds over southwestern Iran, especially in regions near the Persian Gulf, where the R between the DDF and surface winds reaches 0.5. Meanwhile, the summer DDF also shows strong negative correlations (R < −0.4) with soil moisture of the top layer in the middle to southern part of the region. These results highlight the key roles of wind speed, precipitation and soil moisture in determining the interannual variation of dust activities in western and southwestern Iran.

Global Dust Variability Explained by Drought Sensitivity in CMIP6 Models

“…Some studies (e.g., Mahowald et al, 2010) attribute the trends in the North African dust to the severe precipitation deficit while Cowie et al (2013) emphasize the role of surface wind speed on the dust trends. Similarly, the dominant role of wind speed on the dust variability over the Middle East was reported by Kamal et al (2020) and Mashat et al (2020). In these cases, the drought relationships we find are likely the result of wind variability associated with drought in these regions.…”

Integration of Satellite Observation and Dust Trajectory Modeling for Dust Transport and Dispersion Monitoring

“…The main factors in the formation and occurrence of dust storms in Khuzestan are migratory systems of westerlies (west winds) and polar front jet stream (PFJ) (Tavoosi et al 2010;Raispour et al 2016). It is important to mention that dust storms in Khuzestan occur mainly in the late spring (May) (Shahsavani et al 2012) and in the summer (June-July) although some dust events in Khuzestan occur in the winter (Modarres and Sadeghi, 2018;Kamal et al 2020). According to the results of forward Hysplit trajectory modeling from ineternal dust storm (center 1 and center 2), most neighbor provinces of Khuzestan subjected to dust storm with internal origine in cold season.…”

Dust storm index anomaly for sand-dust events monitoring in western Iran and its association with the NDVI and LST anomalies

“…1c). Most of the SDE in the area occurs in spring and summer (Kamal et al 2019) when "Shamal" wind speeds is maximized and the rainfall is minimized (Alizadeh-Choobari et al 2016). Al-Howizeh and Al-Azim marshes are important sources of dust generation in southwestern Iran (Cao et al 2015b).…”

“…However, according to the research background, land surface temperature (LST) has also affected dust events and air quality. The effect of climatic factors, soil moisture, vegetation cover, and human activity on SDE in some areas of western Iran have been investigated in some past works (Akhzari and Haghighi 2015;Akhzari et al 2014;Kamal et al 2019) but no attempt has been made to investigate the effect of NDVI anomaly (NDVIA) and LST anomaly (LSTA) on the DSI anomaly (DSIA) across western Iran. This study has therefore attempted to address this issue.…”