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Title: Integrating Cloud Processes in the Community Atmosphere Model, Version 5.

Abstract

This paper provides a description on the parameterizations of global cloud system in CAM5. Compared to the previous versions, CAM5 cloud parameterization has the following unique characteristics: (1) a transparent cloud macrophysical structure that has horizontally non-overlapped deep cumulus, shallow cumulus and stratus in each grid layer, each of which has own cloud fraction, mass and number concentrations of cloud liquid droplets and ice crystals, (2) stratus-radiation-turbulence interaction that allows CAM5 to simulate marine stratocumulus solely from grid-mean RH without relying on the stability-based empirical empty stratus, (3) prognostic treatment of the number concentrations of stratus liquid droplets and ice crystals with activated aerosols and detrained in-cumulus condensates as the main sources and evaporation-sedimentation-precipitation of stratus condensate as the main sinks, and (4) radiatively active cumulus. By imposing consistency between diagnosed stratus fraction and prognosed stratus condensate, CAM5 is free from empty or highly-dense stratus at the end of stratus macrophysics. CAM5 also prognoses mass and number concentrations of various aerosol species. Thanks to the aerosol activation and the parameterizations of the radiation and stratiform precipitation production as a function of the droplet size, CAM5 simulates various aerosol indirect effects associated with stratus as well as direct effects, i.e., aerosolmore » controls both the radiative and hydrological budgets. Detailed analysis of various simulations revealed that CAM5 is much better than CAM3/4 in the global performance as well as the physical formulation. However, several problems were also identifed, which can be attributed to inappropriate regional tuning, inconsistency between various physics parameterizations, and incomplete model physics. Continuous efforts are going on to further improve CAM5.« less

Authors:
; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1168916
Report Number(s):
PNNL-SA-89206
KP1703020
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Journal of Climate, 27(18):6821-6856
Additional Journal Information:
Journal Name: Journal of Climate, 27(18):6821-6856
Country of Publication:
United States
Language:
English
Subject:
CAM5; Global Cloud Systems; parameterization; Global Cloud Simulation; Community Atmosphere

Citation Formats

Park, S., Bretherton, Christopher S., and Rasch, Philip J. Integrating Cloud Processes in the Community Atmosphere Model, Version 5.. United States: N. p., 2014. Web. doi:10.1175/JCLI-D-14-00087.1.
Park, S., Bretherton, Christopher S., & Rasch, Philip J. Integrating Cloud Processes in the Community Atmosphere Model, Version 5.. United States. doi:10.1175/JCLI-D-14-00087.1.
Park, S., Bretherton, Christopher S., and Rasch, Philip J. Mon . "Integrating Cloud Processes in the Community Atmosphere Model, Version 5.". United States. doi:10.1175/JCLI-D-14-00087.1.
@article{osti_1168916,
title = {Integrating Cloud Processes in the Community Atmosphere Model, Version 5.},
author = {Park, S. and Bretherton, Christopher S. and Rasch, Philip J.},
abstractNote = {This paper provides a description on the parameterizations of global cloud system in CAM5. Compared to the previous versions, CAM5 cloud parameterization has the following unique characteristics: (1) a transparent cloud macrophysical structure that has horizontally non-overlapped deep cumulus, shallow cumulus and stratus in each grid layer, each of which has own cloud fraction, mass and number concentrations of cloud liquid droplets and ice crystals, (2) stratus-radiation-turbulence interaction that allows CAM5 to simulate marine stratocumulus solely from grid-mean RH without relying on the stability-based empirical empty stratus, (3) prognostic treatment of the number concentrations of stratus liquid droplets and ice crystals with activated aerosols and detrained in-cumulus condensates as the main sources and evaporation-sedimentation-precipitation of stratus condensate as the main sinks, and (4) radiatively active cumulus. By imposing consistency between diagnosed stratus fraction and prognosed stratus condensate, CAM5 is free from empty or highly-dense stratus at the end of stratus macrophysics. CAM5 also prognoses mass and number concentrations of various aerosol species. Thanks to the aerosol activation and the parameterizations of the radiation and stratiform precipitation production as a function of the droplet size, CAM5 simulates various aerosol indirect effects associated with stratus as well as direct effects, i.e., aerosol controls both the radiative and hydrological budgets. Detailed analysis of various simulations revealed that CAM5 is much better than CAM3/4 in the global performance as well as the physical formulation. However, several problems were also identifed, which can be attributed to inappropriate regional tuning, inconsistency between various physics parameterizations, and incomplete model physics. Continuous efforts are going on to further improve CAM5.},
doi = {10.1175/JCLI-D-14-00087.1},
journal = {Journal of Climate, 27(18):6821-6856},
number = ,
volume = ,
place = {United States},
year = {2014},
month = {9}
}