Dust storms are common meteorological events in arid and semi-arid regions, particularly in Southwest Iran (SWI). Here we study the relation between drought events in Iraq and dust storms in SWI between 2003 and 2018. The HYSPLIT model showed that central and southern Iraq are the main dust sources for SWI. Mean annual aerosol optical depth (AOD) analysis demonstrated that 2008 and 2009 were the dustiest years since 2003 and there is an increased frequency of summertime extreme dust events in the years 2008 and 2009. The Standardized Precipitation Evapotranspiration Index revealed that drought in Iraq significantly affects dust storms in Iran. Similarly, dramatic desiccation of Iraq wetlands has contributed to increasing fall dust events in SWI. AOD in SWI is highly correlated (−0.76) with previous-month vapor pressure deficit (VPD) over Iraq, demonstrating the potential of VPD for dust event forecasting. Link of the paper: https://iopscience.iop.org/article/10.1088/1748-9326/ab574e/meta

1. Drought Effect on
Dust Storm Severity
and Predictability
Mostafa Javadian
Ali Behrangi
Armin Sorooshian
Department of Hydrology and Atmospheric Sciences
2020 EL DIA DEL AGUA Y LA ATMOSFERA

3. 3
Dust Storm, the Silent Killer in Southwest Iran
Source: World Health Organization

4. 4
Main Goals
1. Exploring the origin of the Southwest Iran dust events
2. Quantifying relationships between major drought events in Iraq and dust events in Southwest Iran
3. Introduce a satellite-observed variable that can potentially be used for prediction of dust events

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Trajectory Analysis of Dust Storms in Southwest Iran
Region of study including the red box representing Iraq
and the black box representing SWI
HYSPLIT backward trajectory frequencies for each month of
2009 for Ahvaz, showing the number of start points of dust
per grid square per number of trajectories.
AhvazHoorolazim
Wetland
Iran
Iraq
Saudi Arabia
Syria
Jordan
Freq. of
being
dust
origin

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Trajectory Analysis of Dust Storms in Southwest Iran
HYSPLIT backward trajectory frequencies for each month of
2009 for Ahvaz, showing the number of start points of dust per
grid square per number of trajectories.
Mean annual wind
rose for the Ahvaz
weather station
Freq. of
being
dust
origin
Precipitation

7. 7
HYSPLIT backward trajectory
frequencies for each month of
2009 for Baghdad, showing
the number of start points of
dust per grid square per
number of trajectories
Trajectory Analysis of Dust Storms in Baghdad, Iraq
Freq. of
being dust
origin

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Satellite AOD Products

9. 9
Spatial distribution of MODIS AOD
Mean monthly AOD (color scale)
based on the period between
2003 and 2018.
• AOD in SWI exceeded other regions
of Iran
• The fluctuation of AOD in central
and southern Iraq was similar to SWI
• Dust events over Iraq are fairly
isolated (i.e., produced locally)
AOD

10. 10
Mean Annual AOD Time Series over Southwest Iran
Scatterplot of Ahvaz station monthly
visibility and its monthly AOD in year 2009
Mean annual AOD over SWI by MISR AOD product
Terra
Aqua

11. 11Number of days with extreme dust events in SWI based on MODIS data
Extreme Dust Event Frequency Analysis over SWI
AOD of Extreme dust event > {[mean monthly AOD] + [3*Standard deviation]}
The number of extreme dust events in JJA
increases dramatically (and exceeds that in
MAM) for years with higher extreme dust events

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Monthly AOD over Southwest Iran
Sep 2006 Sep 2014 Sep 2015
AODs in fall (especially September-October)
are higher in the recent period (2015-2018)
This could be partly related to the fact that
water bodies in the west side of SWI and east
side of Iraq have dramatically shrunk in
recent years due to drought

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Drought Analysis
AOD over SWI exhibits a higher correlation with
SPEI over Iraq than SPEI6 over SWI
The Standardized Precipitation-ET Index (SPEI)

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Correlation between AIRS products (vapor pressure deficit, air
temperature, and relative humidity) over Iraq and AOD over SWI across
different monthly lag times.
Dust Prediction Using AIRS Mission Products
higher VPD in Iraq for the current month
would suggest a higher probability of dust
events in SWI for the subsequent month.
𝑨𝑶𝑫 𝑺𝑾𝑰 = 𝟎. 𝟎𝟓𝟕𝟏𝑽𝑷𝑫 𝑰𝒓𝒂𝒒 + 𝟎. 𝟐𝟏𝟑𝟐
𝐴𝑂𝐷𝑆𝑊𝐼: AOD over Southwest Iran
𝑉𝑃𝐷𝐼𝑟𝑎𝑞: Vapor Pressure deficit over Iraq

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• Most dust events in Southwestern Iran originate over Iraq
• Drought over Iraq is largely responsible for dust events over
Southwest Iran
• Vapor pressure deficit shows skill in predicting dust events with
one month lead time
Key Conclusions

16. 16
Published in the Environmental Research Letters
Funded by:

17. 17
Thank you for your attention!
Ahvaz, Iran. 11/08/2017
javadian@email.arizona.edu
@mostafajavadian