scholarly journals Why Are Tropical Cyclone Tracks over the Western North Pacific Sensitive to the Cumulus Parameterization Scheme in Regional Climate Modeling? A Case Study for Megi (2010)

2014 ◽  
Vol 142 (3) ◽  
pp. 1240-1249 ◽  
Author(s):  
Yuan Sun ◽  
Zhong Zhong ◽  
Wei Lu ◽  
Yijia Hu
Keyword(s):  
Tropical Cyclone ◽  
Climate Modeling ◽  
Deep Convection ◽  
Regional Climate ◽  
Lower Troposphere ◽  
Western Pacific Subtropical High ◽  
Regional Climate Modeling ◽  
Cumulus Parameterization ◽  
Parameterization Schemes ◽  
Cumulus Parameterization Schemes

Abstract The Weather Research and Forecasting Model is employed to simulate Tropical Cyclone (TC) Megi (2010) using the Grell–Devenyi (GD) and Betts–Miller–Janjić (BMJ) cumulus parameterization schemes, respectively. The TC track can be well reproduced with the GD scheme, whereas it turns earlier than observations with the BMJ scheme. The physical mechanism behind different performances of the two cumulus parameterization schemes in the TC simulation is revealed. The failure in the simulation of the TC track with the BMJ scheme is attributed to the overestimation of anvil clouds, which extend far away from the TC center and reach the area of the western Pacific subtropical high (WPSH). Such extensive anvil clouds, which result from the excessively deep convection in the eyewall, eventually lead to a large bias in microphysics latent heating. The warming of the upper troposphere due to the condensation in anvil clouds coupled with the cooling of the lower troposphere due to precipitation evaporation cause a weakening of the WPSH, which in turn is favorable for the early recurvature of Megi.

scholarly journals Evaluating the Performance of Cumulus Convection Parameterization Schemes in Regional Climate Modeling System

2021 ◽  
Author(s):  
Sridhara Nayak ◽  
Suman Maity
Keyword(s):  
Climate Modeling ◽  
Regional Climate ◽  
Regional Climate Modeling ◽  
Horizontal Resolution ◽  
Cumulus Convection ◽  
Convection Scheme ◽  
Parameterization Schemes ◽  
Global Precipitation Climatology Centre ◽  
Convection Schemes ◽  
Convection Parameterization

In this study, we explored the performance of the cumulus convection parameterization schemes of Regional Climate Modeling System (RegCM) towards the Indian summer monsoon (ISM) of a catastrophic year through various numerical experiments conducted with different convection schemes (Kuo, Grell amd MIT) in RegCM. The model is integrated at 60KM horizontal resolution over Indian region and forced with NCEP/NCAR reanalysis. The simulated temperature at 2m and the wind at 10m are validated against the forced data and the total precipitation is compared with the Global Precipitation Climatology Centre (GPCC) observations. We find that the simulation with MIT convection scheme is close to the GPCC data and NCEP/NCAR reanalysis. Our results with three convection schemes suggest that the RegCM with MIT convection scheme successfully simulated some characteristics of ISM of a catastrophic year and may be further examined with more number of convection schemes to customize which convection scheme is much better.

scholarly journals Sensitivity of Tropical Cyclone Track Simulation over the Western North Pacific to Different Heating/Drying Rates in the Betts–Miller–Janjić Scheme

2015 ◽  
Vol 143 (9) ◽  
pp. 3478-3494 ◽  
Author(s):  
Yuan Sun ◽  
Zhong Zhong ◽  
Hong Dong ◽  
Jian Shi ◽  
Yijia Hu
Keyword(s):  
Tropical Cyclone ◽  
Large Scale ◽  
Lower Troposphere ◽  
Western Pacific Subtropical High ◽  
Cumulus Parameterization ◽  
Weather Research And Forecasting ◽  
Upper Troposphere ◽  
Steering Flow ◽  
Correct Representation ◽  
Drying Rates

Abstract The Weather Research and Forecasting Model is employed to examine the sensitivity of simulated tropical cyclone (TC) motion and associated intensity of the western Pacific subtropical high (WSPH) to different heating and drying rates in the Betts–Miller–Janjić (BMJ) cumulus parameterization (CP) scheme. A case study of Tropical Cyclone Megi (2010) is performed. Results indicate that the simulated WPSH strengthens as the heating/drying effects of the BMJ decrease. A strong WPSH subsequently leads to changes in the large-scale steering flow in its southern edge and delays the northward turning of the simulated storm. The associated physical mechanism is revealed. As the heating/drying is overestimated in the BMJ, the model produces unrealistic drying below 500 hPa whereas the atmosphere becomes moist above 500 hPa. Drying in the lower troposphere hinders the activation of the microphysics while moistening in the upper troposphere facilitates the microphysics. As a result, the model generates extensive anvil clouds that extend far away from the TC center and reach the upper troposphere over the WPSH. This leads to a warming in the upper troposphere due to condensation in the anvil clouds, and a cooling in the lower troposphere due to precipitation evaporation below the anvil clouds. Subsequently, the WPSH weakens and the large-scale steering flow becomes anomalously northward, leading to an early recurvature of TC Megi. Results of this study emphasize the importance of a correct representation of anvil clouds in simulating the WPSH and TC track. This study also implies that correcting the heating/drying can be an effective way to reduce errors in simulating the WPSH and TC motion.

scholarly journals Urban Climates and Climate Change

2020 ◽  
Vol 45 (1) ◽  
pp. 411-444 ◽  
Author(s):  
Valéry Masson ◽  
Aude Lemonsu ◽  
Julia Hidalgo ◽  
James Voogt
Keyword(s):  
Climate Change ◽  
Climate Modeling ◽  
Regional Climate ◽  
Urban Climate ◽  
Regional Climate Modeling ◽  
Climate Impact ◽  
Local Climate ◽  
Urban Climatology ◽  
Recent Developments ◽  
Global Agenda

Cities are particularly vulnerable to extreme weather episodes, which are expected to increase with climate change. Cities also influence their own local climate, for example, through the relative warming known as the urban heat island (UHI) effect. This review discusses urban climate features (even in complex terrain) and processes. We then present state-of-the-art methodologies on the generalization of a common urban neighborhood classification for UHI studies, as well as recent developments in observation systems and crowdsourcing approaches. We discuss new modeling paradigms pertinent to climate impact studies, with a focus on building energetics and urban vegetation. In combination with regional climate modeling, new methods benefit the variety of climate scenarios and models to provide pertinent information at urban scale. Finally, this article presents how recent research in urban climatology contributes to the global agenda on cities and climate change.

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