scholarly journals The Impact of Hybrid Usage of a Cumulus Parameterization Scheme on Tropical Convection and Large‐Scale Circulations in a Global Cloud‐System Resolving Model

2018 ◽  
Vol 10 (11) ◽  
pp. 2952-2970 ◽  
Author(s):  
Tomoki Miyakawa ◽  
Akira T. Noda ◽  
Chihiro Kodama
Keyword(s):  
Large Scale ◽  
Tropical Convection ◽  
Cumulus Parameterization ◽  
Parameterization Scheme ◽  
Cloud System ◽  
Cumulus Parameterization Scheme ◽  
The Impact

scholarly journals Sensitivities of Summertime Mesoscale Circulations in the Coastal Carolinas to Modifications of the Kain–Fritsch Cumulus Parameterization

2017 ◽  
Vol 145 (11) ◽  
pp. 4381-4399 ◽  
Author(s):  
Aaron P. Sims ◽  
Kiran Alapaty ◽  
Sethu Raman
Keyword(s):  
Numerical Models ◽  
Deep Convection ◽  
Coastal Region ◽  
Turnover Time ◽  
Cumulus Parameterization ◽  
Parameterization Scheme ◽  
Subgrid Scale ◽  
Mesoscale Circulations ◽  
Near Surface ◽  
The Impact

Two mesoscale circulations, the Sandhills circulation and the sea breeze, influence the initiation of deep convection over the Sandhills and the coast in the Carolinas during the summer months. The interaction of these two circulations causes additional convection in this coastal region. Accurate representation of mesoscale convection is difficult as numerical models have problems with the prediction of the timing, amount, and location of precipitation. To address this issue, the authors have incorporated modifications to the Kain–Fritsch (KF) convective parameterization scheme and evaluated these mesoscale interactions using a high-resolution numerical model. The modifications include changes to the subgrid-scale cloud formulation, the convective turnover time scale, and the formulation of the updraft entrainment rates. The use of a grid-scaling adjustment parameter modulates the impact of the KF scheme as a function of the horizontal grid spacing used in a simulation. Results indicate that the impact of this modified cumulus parameterization scheme is more effective on domains with coarser grid sizes. Other results include a decrease in surface and near-surface temperatures in areas of deep convection (due to the inclusion of the effects of subgrid-scale clouds on the radiation), improvement in the timing of convection, and an increase in the strength of deep convection.

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.

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