Submitted as: model evaluation paper
13 Jun 2023
Submitted as: model evaluation paper |  | 13 Jun 2023
Status: a revised version of this preprint is currently under review for the journal GMD.

Impacts of a double-moment bulk cloud microphysics scheme (NDW6-G23) on aerosol fields in NICAM.19 with a global 14-km grid resolution

Daisuke Goto, Tatsuya Seiki, Kentaroh Suzuki, Hisashi Yashiro, and Toshihiko Takemura

Abstract. In accordance with progression in current capabilities towards high-resolution approaches, applying a convective-permitting resolution to global aerosol models helps comprehend how complex cloud-precipitation systems interact with aerosols. This study investigates the impacts of a double-moment bulk cloud microphysics scheme, i.e., NICAM Double-moment bulk Water 6 developed in this study (NDW6-G23), on the spatiotemporal distribution of aerosols in the Non-hydrostatic ICosahedral Atmospheric Model as part of the version 19 series (NICAM.19) with 14 km grid spacing. The mass concentrations and optical thickness of the NICAM-simulated aerosols are generally comparable to those obtained from in situ measurements, but some aerosol species, especially dust and sulfate, have larger differences among the experiments with NDW6 and NSW6 compared to those among the experiments with different horizontal resolutions, i.e., 14 km and 56 km grid spacing, as shown in a previous study. The simulated aerosol burdens using NDW6 are generally lower than those using NSW6; the instantaneous radiative forcing due to aerosol-radiation interaction (IRFari) is estimated to be -1.57 Wm-2 (NDW6) and -1.86 Wm-2 (NSW6) in the global annual mean values of shortwave all-aerosol radiative forcing at the top of the atmosphere (TOA). This difference among the experiments using different cloud microphysics modules, e.g., 0.29 Wm-2 or 16 % difference in IRFari values, is attributed to a different ratio of column precipitation to the sum of the column precipitation and column liquid cloud water, which strongly determines the magnitude of wet deposition in the simulated aerosols. Since the simulated ratios in the NDW6 experiment are larger than those of the NSW6 result, the scavenging effect of the simulated aerosols in the NDW6 experiment is larger than that in the NSW6 experiment. A large difference between the experiments is also found in the aerosol indirect effect (AIE), i.e., the shortwave effective radiative forcing due to aerosol-cloud interaction (ERFaci) from the present to preindustrial days, which is estimated to be -1.34 Wm-2 (NDW6) and -0.63 Wm-2 (NSW6) in global annual mean values. The magnitude of the ERFaci value in the NDW6 experiment is larger than that in the NSW6 result, probably due to the differences in the susceptibility of the simulated cloud water to the simulated aerosols and partly due to the nonlinear relationship between the ERFaci and AOT under different AOTs. Therefore, this study shows the importance of the impacts of the cloud microphysics module on aerosol distributions through both aerosol wet deposition and AIE.

Daisuke Goto et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gmd-2023-82', Anonymous Referee #1, 24 Jul 2023
    • AC1: 'Reply on RC1', Daisuke Goto, 05 Sep 2023
  • RC2: 'Comment on Goto et al. (2023GMDD)', Anonymous Referee #2, 30 Jul 2023
    • AC2: 'Reply on RC2', Daisuke Goto, 05 Sep 2023
  • RC3: 'Comments on gmd-2023-82', Anonymous Referee #3, 05 Aug 2023
    • AC3: 'Reply on RC3', Daisuke Goto, 05 Sep 2023

Daisuke Goto et al.

Daisuke Goto et al.


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Short summary
Global climate models with coarse grid sizes include uncertainties about the processes in aerosol-cloud-precipitation interactions. To reduce this uncertainty, in this study we performed numerical simulations using a new version of our global aerosol transport model with a finer grid size over a longer period than our previous study. As a result, we found that the cloud microphysics module influences the aerosol distributions through both aerosol wet deposition and aerosol-cloud interactions.