Development and Implementation of a Physics‐Based Convective Mixing Scheme in the Community Multiscale Air Quality Modeling Framework. (16th June 2021)

• Record Type: Journal Article
• Authors: Pouyaei, Arman; Sadeghi, Bavand; Choi, Yunsoo; Jung, Jia; Souri, Amir H.; Zhao, Chun; Song, Chul Han
• Is Part Of: Journal of advances in modeling earth systems. Volume 13:Number 6(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-06-16
• Subjects: updraft -- CMAQ -- KF‐convection -- KORUS‐AQ -- downdraft -- CO; Geological modeling -- Periodicals; Climatology -- Periodicals; Geochemical modeling -- Periodicals; 551.5011
• DOI: 10.1029/2021MS002475
• Languages: English
• ISSNs: 1942-2466

Abstract

Abstract: To improve the representation of convective mixing of atmospheric pollutants in the presence of clouds, we developed a convection module based on Kain and Fritsch (KF) method and implemented it in the Community Multiscale Air Quality model. The KF‐convection method is a mass‐flux‐based model that accounts for updraft flux, downdraft flux, entrainment, detrainment, and the subsidence effect. The method is consistent with the convection parametrization of the meteorology model. We apply the KF‐convection model to an idealized case and to a reference setup prepared for East Asia during the KORUS‐AQ campaign period to investigate its impact on carbon monoxide (CO) concentration at various atmospheric altitudes. We investigate the impact of KF‐convection on the horizontal distribution of CO concentrations by comparing it to aircraft measurements and the MOPITT CO column. We further discuss two types of impacts of KF‐convection: the direct impact caused by vertical movement of CO concentrations by updraft or downdraft and the indirect impact caused by transport of lifted CO concentrations to another region. May 12 saw a high indirect impact originating from the Shanghai region at higher altitudes and a high direct impact of updraft fluxes at 1 km altitude. However, May 26 revealed an immense updraft increasing higher altitude concentrations (up to 40 ppbv) and diverse indirect impacts over the region of the study (±50 ppbv). The overall comparison shows a strong connection between differences in the amount of concentration caused by the direct impact at each altitude with the presence of an updraft at that altitude. The developed model can be employed in large domains (i.e., East Asia, Europe, North America, and Northern Hemisphere) with sub‐grid scale cloud modeling to include the impacts of convection. Plain Language Summary: We developed a more physically accurate convective mixing model based on the Kain and Fritsch scheme for a chemical transport model. We verified the physical processes involved in the developed scheme for an idealized case and then implemented it into the Community Multiscale Air Quality modeling platform. We also investigated the developed convection model on the vertical and spatial distribution of carbon monoxide over East Asia during the KORUS‐AQ aircraft campaign. We investigated the impact by comparing the results of these models to aircraft measurements and satellite retrievals. Furthermore, we separated the impact of convective transport over the study region into two types: the direct impact caused by vertical convective fluxes, which changed the vertical distribution of concentrations, and the indirect impact originating from vertical fluxes in neighboring regions and leading to spatial differences on vertical layers in the region of study. The developed model can be employed in large domains (i.e., East Asia, Europe, North America, and Northern Hemisphere) with sub‐grid scale cloud modeling to include the convection impacts. Key Points: Implemented a more physically accurate convection mixing model based on Kain and Fritsch scheme into Community Multiscale Air Quality (CMAQ) modeling Investigated the convection model on the vertical and spatial distribution of air pollutants over East Asia using CMAQ modeling Two convective transport impacts: (a) direct impact by vertical convective fluxes and (b) indirect impact originating from vertical fluxes