Assessment and prediction of dust emissions, deposition and radiation forcing in Central Asia

Abstract

Dust aerosols significantly influence climate by modulating radiative balance and cloud processes. This study integrates MERRA-2 reanalysis data and the CMIP6 multi-model ensemble to assess the spatiotemporal evolution of dust emissions, deposition, and associated radiative effects in Central Asia from 1980 to 2100. Four SSP scenarios project that dust emissions in Central Asia exhibit a high-emission, high-deposition pattern with primary sources exceeding 15 µg m−2 s−1. The deposition area substantially exceeds the source area (maximum > 8 µg m−2 s−1). Cross-scenario analysis demonstrates that dust emissions are highly sensitive to climate policy, with end-of-century emissions in the SSP5-8.5 high-emission scenario increasing by 94.9 % relative to the baseline period. In contrast, emissions under the SSP1-2.6 low-carbon pathway vary by only 4.5 %. Simulations using the SBDART model show that aerosol direct radiative forcing (ADRF) from dust in Central Asia under clear-sky conditions exhibits a vertical gradient, with cooling at the top of the atmosphere (TOA) and heating within the atmosphere, yielding a net negative forcing at the TOA, with a minimum of < -10 W m−2 near the Caspian Sea. Peak positive forcing within the atmosphere, observed in spring, reaches 10.0 W m−2. Increased dust emissions reduce shortwave radiation at the surface by up to -20 W m−2. Ground-based observations indicate seasonal variations in the dust-induced heating rate, with peak radiative forcing in spring at Kashgar (93.0 W m−2) and a maximum near-surface heating rate of 2.6 K d−1. In contrast, the near-surface heating rate at Issyk-Kul Lake in autumn (0.34 K d−1) is approximately four times higher than in spring (0.08 K d−1).