Modelling the 2021 East Asia super dust storm using FLEXPART and FLEXDUST and its comparison with reanalyses and observations

Abstract

The 2021 East Asia sandstorm began from the Eastern Gobi desert steppe in Mongolia on March 14, and later spread to northern China and the Korean Peninsula. It was the biggest sandstorm to hit China in a decade, causing severe air pollution and a significant threat to human health. Capturing and predicting such extreme events is critical for society. The Lagrangian particle dispersion model FLEXPART and the associated dust emission model FLEXDUST have been recently developed and applied to simulate global dust cycles. However, how well the model captures Asian dust storm events remains to be explored. In this study, we applied FLEXPART to simulate the recent 2021 East Asia sandstorm, and evaluated its performance comparing with observation and observation-constrained reanalysis datasets, such as the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) and CAMS global atmospheric composition forecasts (CAMS-F). We found that the default setting of FLEXDUST substantially underestimates the strength of dust emission and FLEXPART modelled dust concentration in this storm compared to that in MERRA-2 and CAMS-F. An improvement of the parametrization of bare soil fraction, topographical scaling, threshold friction velocity and vertical dust flux scheme based on Kok et al. (Atmospheric Chemistry and Physics, 2014, 14, 13023–13041) in FLEXDUST can reproduce the strength and spatio-temporal pattern of the dust storm comparable to MERRA-2 and CAMS-F. However, it still underestimates the observed spike of dust concentration during the dust storm event over northern China, and requires further improvement in the future. The improved FLEXDUST and FLEXPART perform better than MERRA-2 and CAMS-F in capturing the observed particle size distribution of dust aerosols, highlighting the importance of using more dust size bins and size-dependent parameterization for dust emission, and dry and wet deposition schemes for modelling the Asian dust cycle and its climatic feedbacks.

Modern‐Type Eolian Regime and Global Cooling‐Modulated Dust Provenance in the Late Paleogene of Central‐East Asia

“…As the FLEXPART output consists of 3D fields of emission sensitivities, we took the emission sensitivity of the lowest 100 m and coupled it with dust emission fluxes from a FLEXDUST dust emission model (Groot Zwaaftink et al., 2017). We used a version of FLEXDUST that contains several changes to better represent the East Asian dust cycle (Tang et al., 2023). By coupling the dust flux with the emission sensitivity, we obtained source contribution maps, which can be spatially integrated to give the dust deposition rate at the site.…”

Spatial source contribution and interannual variation in deposition of dust aerosols over the Chinese Loess Plateau

“…The dust emitted in FLEXDUST is assumed to have a volume size distribution between 0.2 and 20 µm according to the brittle fragmentation theory described in . Tang et al (2023) identified several weaknesses in the way dust-emitting areas in East Asia were represented in the original FLEXDUST version. Therefore, we use the updated version of FLEX-DUST by Tang et al (2023), which includes several changes to better represent present day dust emission areas in East Asia.…”

“…Tang et al (2023) identified several weaknesses in the way dust-emitting areas in East Asia were represented in the original FLEXDUST version. Therefore, we use the updated version of FLEX-DUST by Tang et al (2023), which includes several changes to better represent present day dust emission areas in East Asia. To avoid confusion with the standard version of FLEXDUST, we refer to the updated Tang et al (2023) version of FLEXDUST as FLEXDUST-EA.…”

“…Therefore, we use the updated version of FLEX-DUST by Tang et al (2023), which includes several changes to better represent present day dust emission areas in East Asia. To avoid confusion with the standard version of FLEXDUST, we refer to the updated Tang et al (2023) version of FLEXDUST as FLEXDUST-EA. Changes in FLEXDUST-EA compared to FLEX-DUST include: (1) the parameterization of vertical dust flux described by with a modified parameter for the calculation of the threshold friction velocity according to , (2) the soil texture dataset in the ISRIC SoilGrids dataset described by de Sousa et al ( 2020), (3) new improved topographical erodibility scaling, and (4) herbaceous and crop land cover types in the GLC-NMO land cover dataset are considered to have a potential to emit dust in addition to bare ground and sparse vegetation.…”

“…Our setup using FLEXPART coupled with FLEXDUST-EA was developed to represent East Asian sources and Tang et al (2023) showed that it can realistically simulate the evolution of single dust events, compared to both observations and reanalysis. Here, we evaluated FLEXDUST-EA by comparing it with MERRA-2 over a longer time period.…”