Preprints
https://doi.org/10.5194/egusphere-2023-2772
https://doi.org/10.5194/egusphere-2023-2772
05 Dec 2023
 | 05 Dec 2023
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

Radiative cooling and atmospheric perturbation effects of dust aerosol from the Aralkum Desert in Central Asia

Jamie R. Banks, Bernd Heinold, and Kerstin Schepanski

Abstract. The Aralkum is a new desert created by the desiccation of the Aral Sea since the 1960s, and is an efficient source of dust aerosol which may perturb the regional Central Asian radiation balance. COSMO-MUSCAT model simulations are used to quantify the direct radiative effects (DREs) of Aralkum dust, and investigate the associated perturbations to the atmospheric environment. Considering scenarios of ‘Past’ and ‘Present’ defined by differences in surface water coverage, it is found that in the Present scenario the yearly mean net surface DRE across the Aralkum is -1.34±6.19 W m-2, of which -0.15±1.19 W m-2 comes from dust emitted by the Aralkum. Meanwhile in the atmosphere the yearly mean DRE is -0.62±2.91 W m-2, of which -0.05±0.51 W m-2 comes from Aralkum dust: on the yearly timescale Aralkum dust is cooling both at the surface and in the atmosphere. The daytime surface cooling effect (solar zenith angle ≲70–80°) outweighs both the nighttime heating effect and the corresponding atmospheric daytime (solar zenith angle ≲60–70°) heating and nighttime cooling effects. Instantaneous Aralkum dust DREs contribute up to -116 W m-2 of surface cooling and +54 W m-2 of atmospheric heating. Aralkum dust perturbs the surface pressure in the vicinity of the Aralkum by up to +0.76 Pa on the monthly timescale, implying a strengthening of the Siberian High in winter and a weakening of the Central Asian Heat Low in summer.

Jamie R. Banks, Bernd Heinold, and Kerstin Schepanski

Status: open (until 03 Mar 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-2772', Anonymous Referee #1, 27 Feb 2024 reply
  • RC2: 'Comment on egusphere-2023-2772', Anonymous Referee #1, 27 Feb 2024 reply
Jamie R. Banks, Bernd Heinold, and Kerstin Schepanski
Jamie R. Banks, Bernd Heinold, and Kerstin Schepanski

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Short summary
The Aralkum is a new desert in Central Asia formed by the desiccation of the Aral Sea. This has created a source of atmospheric dust, with implications for the balance of solar and thermal radiation. Simulating these effects using a dust transport model, we find that Aralkum dust adds radiative cooling effects to the surface and atmosphere on average, but also adds heating events. Increases in surface pressure due to Aralkum dust strengthen the Siberian high and weaken the summer Asian heat low.