Improving dust simulations in WRF-Chem v4.1.3 coupled with the GOCART aerosol module

Alexander Ukhov, Ravan Ahmadov, Georg Grell, Georgiy L. Stenchikov

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Abstract. In this paper, we rectify inconsistencies that emerge in the Weather Research and Forecasting model with chemistry (WRF-Chem) v3.2 code when using the Goddard Chemistry Aerosol Radiation and Transport (GOCART) aerosol module. These inconsistencies have been reported, and corrections have been implemented in WRF-Chem v4.1.3. Here, we use a WRF-Chem experimental setup configured over the Middle East (ME) to estimate the effects of these inconsistencies. Firstly, we show that the old version underestimates the PM2.5 diagnostic output by 7 % and overestimates PM10 by 5 % in comparison with the corrected one. Secondly, we demonstrate that submicron dust particles' contribution was incorrectly accounted for in the calculation of optical properties. Therefore, aerosol optical depth (AOD) in the old version was 25 %–30 % less than in the corrected one. Thirdly, we show that the gravitational settling procedure, in comparison with the corrected version, caused higher dust column loadings by 4 %–6 %, PM10 surface concentrations by 2 %–4 %, and mass of the gravitationally settled dust by 5 %–10 %. The cumulative effect of the found inconsistencies led to the significantly higher dust content in the atmosphere in comparison with the corrected WRF-Chem version. Our results explain why in many WRF-Chem simulations PM10 concentrations were exaggerated. We present the methodology for calculating diagnostics we used to estimate the impacts of introduced code modifications. We share the developed Merra2BC interpolator, which allows processing Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2) output for constructing initial and boundary conditions for chemical species and aerosols.
Original languageEnglish (US)
Pages (from-to)473-493
Number of pages21
JournalGeoscientific Model Development
Issue number1
StatePublished - Jan 25 2021

Bibliographical note

KAUST Repository Item: Exported on 2021-01-27
Acknowledged KAUST grant number(s): URF/1/2180-01-01
Acknowledgements: In this work, we used AERONET data from the KAUST Campus site that was maintained by Illia Shevchenko with the help of the NASA Goddard Space Flight Center AERONET team. We thank Brent Holben and Alexander Smirnov for the monitoring and regular calibrations of our instruments. We also used data from the Sede Boker and Mezaira sites and would like to thank their principal investigators (Arnon Karnieli and Brent Holben). For computer time, this research used the resources of the Supercomputing Laboratory at KAUST.
The authors also would like to thank the three anonymous reviewers for their helpful comments.


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