The Contribution of the Former Aral Sea and Other Desiccating Lakes to the Prevalence of Dust Storms in Central Asia and the Middle East

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EGU21-1113 https://doi.org/10.5194/egusphere-egu21-1113 EGU General Assembly 2021 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License.

The contribution of the former Aral Sea and other desiccating lakes to the prevalence of dust storms in Central Asia and the Middle East

Jamie Banks, Bernd Heinold, and Kerstin Schepanski Leibniz Institute for Tropospheric Research, Leipzig, Germany ([email protected])

The 'Aralkum' desert (the former Aral Sea) in Central Asia is a comparatively new desert that has formed over the past several decades due to water mismanagement associated with the inflowing Amu Darya and Syr Darya rivers, and is now a known source of dust aerosol in the region. It is known that recently dry lakebeds can be efficient dust sources, due to the availability of readily erodible alluvial sediments. As a dry lakebed with a new area of over 60,000 km2 exposed to aeolian wind erosion the Aralkum has become a significant driver of dust storms in the region. Other such lakebed dust sources in the Central Asian region include the Sistan Basin on the border between Afghanistan and Iran, and Lake Urmia in Iran. However due to a paucity of measurement sites it is difficult to quantify the behaviour and consequences of dust activity in the region.

Using the dust transport model COSMO-MUSCAT we simulate dust emissions over the course of one year from these relatively new dust sources, exploring the resultant dust emission and transport patterns, quantifying the radiative effects of this dust, and assessing the viability of measuring such dust using remote sensing techniques. Making use of the Global Surface Water dataset (produced by the Copernicus Programme) in order to define the surface water coverage in various epochs, we make estimates of dust emissions for the Central Asian and Middle Eastern region under three scenarios: 1) the 'Past', representative of water coverage in the 1980s; 2) the 'Present', representative of water coverage in the 2010s; and 3) the 'Aralkum' scenario, representing only dust emissions from the present-era Aralkum. In the Present scenario we estimate that the Aralkum area (here considered as 43-47°N, 58-62°E) emitted 28 Tg of dust over the course of a year from March 2015 to March 2016, out of 272 Tg produced by the wider Middle Eastern and Central Asian region. However ~66% of these Aralkum emissions occurred when the cloud cover was > 95%, raising questions as to the extent to which dust storm activity from the Aralkum is measurable. Modelling is therefore a particularly useful tool, complementary to remote sensing measurements, to understand dust activity in a region characterised by dramatic human- induced changes to the natural environment.