Preprints
https://doi.org/10.5194/gmd-2022-95
https://doi.org/10.5194/gmd-2022-95
Submitted as: model evaluation paper
18 May 2022
Submitted as: model evaluation paper | 18 May 2022
Status: this preprint is currently under review for the journal GMD.

Impacts of Ice-Particle Size Distribution Shape Parameter on Climate Simulations with the Community Atmosphere Model Version 6 (CAM6)

Wentao Zhang1, Xiangjun Shi1, and Chunsong Lu2 Wentao Zhang et al.
  • 1School of Atmospheric Sciences, Nanjing University of Information Science and Technology, Nanjing 210044, China
  • 2Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China

Abstract. The impacts of the ice crystal size distribution shape parameter (μi) were considered in the two-moment bulk cloud microphysics scheme of the Community Atmosphere Model Version 6 (CAM6). The calculating formulas of statistical mean radii indicate that, under the same mass (qi) and number (Ni) of ice crystals, the ratios of the mass-weighted radius (Rqi, not related to μi) to other statistical mean radii (e.g., effective radiative radius) are completely determined by μi. Off-line tests show that μi has a significant impact on the cloud microphysical processes owing to the μi-induced changes in ice crystal size distribution and statistical mean radii (excluding Rqi). Climate simulations show that increasing μi would lead to higher qi and lower Ni in most regions, and these impacts can be explained by the changes in cloud microphysical processes. After increasing μi from 0 to 5, the longwave cloud radiative effect increases (stronger warming effect) by 5.58 W m−2 (25.11 %), and the convective precipitation rate decreases by −0.12 mm day−1 (7.64 %). In short, the impacts of μi on climate simulations are significant and the main influence mechanisms are also clear. This suggests that the μi-related processes deserve to be parameterized in a more realistic manner.

Wentao Zhang et al.

Status: open (until 27 Jul 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Wentao Zhang et al.

Wentao Zhang et al.

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Short summary
The two-moment bulk cloud microphysics scheme used in CAM6 was modified to consider the impacts of ice crystal size distribution shape parameter (μi). After that, how the μi impacts cloud microphysical processes and then climate simulations is clearly illustrated by off-line tests and CAM6 model experiments. Our results and findings are useful for the further development of μi-related parameterizations.