A Convective Cloud Model for Use in a Cumulus Parameterization Scheme

1994 ◽  
Vol 122 (1) ◽  
pp. 165-182 ◽  
Author(s):  
Patrick A. Haines ◽  
Wen-Yih Sun
Keyword(s):  
Cloud Model ◽  
Convective Cloud ◽  
Cumulus Parameterization ◽  
Parameterization Scheme ◽  
Cumulus Parameterization Scheme

scholarly journals A Mass-Flux Cumulus Parameterization Scheme across Gray-Zone Resolutions

2017 ◽  
Vol 145 (2) ◽  
pp. 583-598 ◽  
Author(s):  
Young Cheol Kwon ◽  
Song-You Hong
Keyword(s):  
South Korea ◽  
Mass Flux ◽  
Convective Cloud ◽  
Cumulus Parameterization ◽  
Parameterization Scheme ◽  
Cloud Base ◽  
Gray Zone ◽  
Cumulus Parameterization Scheme ◽  
Simulated Precipitation ◽  
Convective Inhibition

A method that enables a mass-flux cumulus parameterization scheme (CPS) to work seamlessly in various model grids across CPS gray-zone resolutions is proposed. The convective cloud-base mass flux, convective inhibition, and convective detrainment in the simplified Arakawa–Schubert (SAS) scheme are modified to be functions of the convective updraft fraction. The combination of two updraft fractions is used to modulate the cloud-base mass flux; the first one depends on the horizontal grid space and the other is a function of the grid-scale and convective vertical velocity. The convective inhibition and detrainment of hydrometeors are also modified to be a function of the grid-size-dependent convective updraft fraction. A set of sensitivity experiments with the Weather Research and Forecasting (WRF) Model is conducted for a heavy rainfall case over South Korea. The results show that the revised SAS CPS outperforms the original SAS. At 3 and 1 km, the precipitation core over South Korea is well reproduced by the experiments with the revised SAS scheme. On the contrary, the simulated precipitation is widespread in the case of the original SAS experiment and there are multiple spurious cores when the CPS is removed at those resolutions. The modified mass flux at the cloud base is found to play a major role in organizing the grid-scale precipitation at the convective core. A 1-month simulation at 3 km confirms that the revised scheme produces slightly better summer monsoonal precipitation results as compared to the typical model setup without CPS.

Parameter Tuning and Calibration of RegCM3 with MIT–Emanuel Cumulus Parameterization Scheme over CORDEX East Asia Domain

2014 ◽  
Vol 27 (20) ◽  
pp. 7687-7701 ◽  
Author(s):  
Liwei Zou ◽  
Yun Qian ◽  
Tianjun Zhou ◽  
Ben Yang
Keyword(s):  
East Asia ◽  
Regional Climate ◽  
Cumulus Parameterization ◽  
Parameterization Scheme ◽  
Cumulus Parameterization Scheme ◽  
Convection Scheme ◽  
Total Rainfall ◽  
Low Level ◽  
Positive Effects ◽  
Cordex East Asia

Abstract In this study, the authors calibrated the performance of the Regional Climate Model, version 3 (RegCM3), with the Massachusetts Institute of Technology (MIT)–Emanuel cumulus parameterization scheme over the Coordinated Regional Climate Downscaling Experiment (CORDEX) East Asia domain by tuning seven selected parameters based on the multiple very fast simulated annealing (MVFSA) approach. The seven parameters were selected based on previous studies using RegCM3 with the MIT–Emanuel convection scheme. The results show the simulated spatial pattern of rainfall, and the probability density function distribution of daily rainfall rates is significantly improved in the optimal simulation. Sensitivity analysis suggests that the parameter relative humidity criteria (RHC) has the largest effect on the model results. Followed by an increase of RHC, an increase of total rainfall is found over the northern equatorial western Pacific, mainly contributed by the increase of explicit rainfall. The increases of the convergence of low-level water vapor transport and the associated increases in cloud water favor the increase of explicit rainfall. The identified optimal parameters constrained by total rainfall have positive effects on the low-level circulation and surface air temperature. Furthermore, the optimized parameters based on the chosen extreme case are transferable to a normal case and the model’s new version with a mixed convection scheme.

scholarly journals A Spectral Cumulus Parameterization Scheme Interpolating between Two Convective Updrafts with Semi-Lagrangian Calculation of Transport by Compensatory Subsidence

2015 ◽  
Vol 143 (2) ◽  
pp. 597-621 ◽  
Author(s):  
Hiromasa Yoshimura ◽  
Ryo Mizuta ◽  
Hiroyuki Murakami
Keyword(s):  
Atmospheric Model ◽  
Cumulus Parameterization ◽  
Parameterization Scheme ◽  
Natural Material ◽  
Layer By Layer ◽  
Cumulus Parameterization Scheme ◽  
Material Transport ◽  
Cumulus Scheme ◽  
Global Atmospheric Model ◽  
Lagrangian Scheme

Abstract The authors have developed a new spectral cumulus parameterization scheme that explicitly considers an ensemble of multiple convective updrafts by interpolating in-cloud variables between two convective updrafts with large and small entrainment rates. This cumulus scheme has the advantages that the variables in entraining and detraining convective updrafts are calculated in detail layer by layer as in the Tiedtke scheme, and that a spectrum of convective updrafts with different heights due to the difference in entrainment rates is explicitly represented, as in the Arakawa–Schubert scheme. A conservative and monotonic semi-Lagrangian scheme is used for calculation of transport by convection-induced compensatory subsidence. Use of the semi-Lagrangian scheme relaxes the mass-flux limit due to the Courant–Friedrichs–Lewy (CFL) condition, and moreover ensures nonnegative natural material transport. A global atmospheric model using this cumulus scheme gives an atmospheric simulation that agrees well with the observational climatology.

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