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Simulating Urban Flow and Dispersion in Beijing by Coupling a CFD model with the wrf model

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Advances in Atmospheric Sciences 2013年第6期30卷 1663-1678页

作者：缪育聪刘树华陈笔澄张碧辉王姝李书严 Department of Atmospheric and Oceanic Sciences School of Physics Peking University National Meteorological Center China Meteorological Administration Beijing Regional Climate Center Beijing Meteorological Bureau

The airflow and dispersion of a pollutant in a complex urban area of Beijing, China, were numerically examined by coupling a Computational Fluid Dynamics （CFD） model with a mesoscale weather model. The models used were Open Source Field Operation and Manipulation （OpenFOAM） software package and Weather Research and Forecasting （wrf） model. OpenFOAM was firstly validated against wind-tunnel experiment data. Then, the wrf model was integrated for 42 h starting from 0800 LST 08 September 2009, and the coupled model was used to compute the flow fields at 1000 LST and 1400 LST 09 September 2009. During the wrf-simulated period, a high pressure system was dominant over the Beijing area. The wrf-simulated local circulations were characterized by mountain valley winds, which matched well with observations. Results from the coupled model simulation demonstrated that the airflows around actual buildings were quite different from the ambient wind on the boundary provided by the wrf model, and the pollutant dispersion pattern was complicated under the influence of buildings. A higher concentration level of the pollutant near the surface was found in both the step-down and step-up notches, but the reason for this higher level in each configurations was different： in the former, it was caused by weaker vertical flow, while in the latter it was caused by a downward-shifted vortex. Overall, the results of this study suggest that the coupled wrf-OpenFOAM model is an important tool that can be used for studying and predicting urban flow and dispersions in densely built-up areas.

关键词： wrf model CFD model OpenFOAM dispersion.

Numerical Simulations of an Advection Fog Event over Shanghai Pudong International Airport with the wrf model

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Journal of Meteorological Research 2017年第5期31卷 874-889页

作者： Caiyan LIN Zhongfeng ZHANG Zhaoxia PU Fengyun WANG Aviation Meteorological Center Air Traffic Management Bureau Civil Aviation Administration of China Department of Atmospheric Sciences University of Utah Meteorological Center East China Air Traffic Management BureauCivil Aviation Administration of China

A series of numerical simulations is conducted to understand the formation, evolution, and dissipation of an advec- tion fog event over Shanghai Pudong International Airport （ZSPD） with the Weather Research and Forecasting （wrf） model. Using the current operational settings at the Meteorological Center of East China Air Traffic Manage- ment Bureau, the wrf model successfully predicts the fog event at ZSPD. Additional numerical experiments are per- formed to examine the physical processes associated with the fog event. The results indicate that prediction of this particular fog event is sensitive to microphysical schemes for the time of fog dissipation but not for the time of fog onset. The simulated timing of the arrival and dissipation of the fog, as well as the cloud distribution, is substantially sensitive to the planetary boundary layer and radiation （both longwave and shortwave） processes. Moreover, varying forecast lead times also produces different simulation results for the fog event regarding its onset and duration, sug- gesting a trade-off between more accurate initial conditions and a proper forecast lead time that allows model physi- cal processes to spin up adequately during the fog simulation. The overall outcomes from this study imply that the complexity of physical processes and their interactions within the wrf model during fog evolution and dissipation is a key area of future research.

关键词： advection fog physical parameterization numerical prediction forecast lead time wrf model

Simulation and Projection of Changes in Rainy Season Precipitation over China Using the wrf model

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Acta meteorologica Sinica 2013年第4期27卷 577-584页

作者：王树舟于恩涛 College of Atmospheric Sciences Nanjing University of Information Science & Technology Nansen-Zhu International Research Center Institute of Atmospheric Physics Chinese Academy of Sciences Climate Change Research Center Chinese Academy of Sciences

The Weather Research and Forecasting （wrf） model is used in a regional climate model configuration to simulate past precipitation climate of China during the rainy season （May-September） of 1981-2000, and to investigate potential future （2041-2060 and 2081-2100） changes in precipitation over China relative to the reference period 1981-2000. wrf is run with initial conditions from a coupled general circulation model, i.e., the high-resolution version of MIROC （model for Interdisciplinary Research on Climate）. wrf reproduces the observed distribution of rainy season precipitation in 1981-2000 and its interannual variations better than MIROC. MIROC projects increases in rainy season precipitation over most parts of China and decreases of more than 25 mm over parts of Taiwan and central Tibet by the mid-21st century. wrf projects decreases in rainfall over southern Tibetan Plateau, Southwest China, and northwestern part of Northeast China, and increases in rainfall by more than 100 mm along the southeastern margin of the Tibetan Plateau and over the lower reaches of the Yangtze River during 2041-2060. MIROC projects further increases in rainfall over most of China by the end of the 21st century, although simulated rainfall decreases by more than 25 mm over parts of Taiwan, Guangxi, Guizhou, and central Tibet. wrf projects increased rainfall of more than 100 mm along the southeastern margin of the Tibetan Plateau and over the lower reaches of the Yangtze River and decreased rainfall over Southwest China, and southern Tibetan Plateau by the end of the 21st century.

关键词： wrf model dynamical downscaling rainy season precipitation interannual variation

Move a Tropical Cyclone with 4D-Var and Vortex Dynamical Initialization in wrf model

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Journal of Tropical Meteorology 2021年第3期27卷 191-200页

作者： WANG Ting PENG Yue-hua ZHANG Bang-lin LEUNG Jeremy Cheuk-Hin SHI Wei-lai Mail Box 5111 Beijing 100094 China Dalian Naval Academy DalianLiaoning 116018 China Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029 China Guangzhou Institute of Tropical and Marine Meteorology/Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction China Meteorological AdministrationGuangzhou 510000 China College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410073 China

Previous studies showed that 4 D-Var technique used for data assimilation could be modified for weather control. This study demonstrates the ability of 4 D-Var to influence the future path of a tropical cyclone by calculating perturbations in wrf simulation. Given the background error covariance matrix, the initial field is improved by the vortex dynamic initialization technique. Our results show that 4 D-Var can be applied to control the trajectory of simulated tropical cyclones by producing "optimal" perturbations. In the numerical simulation experiment of Typhoon Mitag in 2019, after this kind of weather control similar to data assimilation, the tropical cyclone moved obviously,and the damaging wind over the coastline weakened. The prediction results after the initial field modified by 4 D-Var have a great change, and the position of the tropical cyclone moved about 0.5° southeastward after assimilation,which misses the southeast coast of China. Moreover, the damaging wind is also weakened. Since the 4 D-Var is premised on the assumption that the model is perfect and does not consider the model error, then the research plan to consider model error and introduce new methods is discussed in the paper.

关键词： 4D-Var weather control Typhoon Mitag wrf model vortex dynamical initialization

A NUMERICAL STUDY OF TROPICAL DEEP CONVECTION USING wrf model

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Journal of Tropical Meteorology 2010年第3期16卷 247-254页

作者：李嘉鹏银燕金莲姬张成竹 CMA Key Laboratory for Atmospheric Physics and Environment Nanjing University of Information Science & Technology Zhejiang Meteorological Observatory

The Weather Research Forecast model (wrf) configured with high resolution and NCEP 1°×1° reanalysis data were used to simulate the development of a tropical deep convection over the Tiwi Islands,northern Australia,and to investigate the sensitivity of model results to model configuration and parameterization schemes of microphysical *** simulation results were compared with available *** results show that the model can reproduce most of the important characteristics of the observed diurnal evolution of the convection,including the initiation of convection along the sea-breeze front,which is then reinforced by downdraft outflows,merging of cells and the formation of a deep convective ***,further improvement is needed to simulate more accurately the location and the time for initiation of the deep convective *** tests show that double-nesting schemes are more accurate than the non-nesting schemes in predicting the distribution and intensity of precipitation as far as this particular case is ***,microphysical schemes also have an effect on the simulated amount of *** is shown that the best agreement is reached between the simulation results and observations when the Purdue Lin scheme is used.

关键词： tropical deep convection wrf model parameterization of microphysical processes nesting sensitivity experiment

Analysis of Wind Power Assessment Based on the wrf model

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Atmospheric and Oceanic Science Letters 2014年第2期7卷 126-131页

作者： LI Ji-Hang GUO Zhen-Hai WANG Hui-Jun LI Ji-Hang WANG Hui-Jun Nansen-Zhu International Research Centre (NZC) Institute of Atmospheric Physics the Chinese Academy of Sciences Beijing 100029 China State Key Laboratory of Numerical modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG) Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China University of the Chinese Academy of Sciences Beijing 100049 China

Assessing wind energy is a key step in selecting a site for a wind farm. The accuracy of the assessment is essential for the future operation of the wind farm. There are two main methods for assessing wind power: one is based on observational data and the other relies on mesoscale numerical weather prediction(NWP). In this study, the wind power of the Liaoning coastal wind farm was evaluated using observations from an anemometer tower and simulations by the Weather Research and Forecasting(wrf) model, to see whether the wrf model can produce a valid assessment of the wind power and whether the downscaling process can provide a better evaluation. The paper presents long-term wind data analysis in terms of annual, seasonal, and diurnal variations at the wind farm, which is located on the east coast of Liaoning Province. The results showed that, in spring and summer, the wind speed, wind direction, wind power density, and other main indicators were consistent between the two methods. However, the values of these parameters from the wrf model were significantly higher than the observations from the anemometer tower. Therefore, the causes of the differences between the two methods were further analyzed. There was much more deviation in the original material, National Centers for Environmental Prediction(NCEP) final(FNL) Operational Global Analysis data, in autumn and winter than in spring and summer. As the region is vulnerable to cold-air outbreaks and windy weather in autumn and winter, and the model usually forecasted stronger high or low systems with a longer duration, the predicted wind speed from the wrf model was too large.

关键词： wind power assessment anemometer tower data wrf model variance analysis

Intercomparison of different physics schemes in the wrf model over the Asian summer monsoon region

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Atmospheric and Oceanic Science Letters 2016年第3期9卷 169-177页

作者： QUE Lin-Jing QUE Wei-Lun FENG Jin-Ming College of Global Change and Earth System Science (GCESS) Beijing Normal University Longjiang County Meteorological Bureau Heilongjiang Meteorological Bureau Key Laboratory of Regional Climate–Environment for Temperate East Asia (RCETEA) Institute of Atmospheric Physics Chinese Academy of Sciences

Enhancing the ability of the wrf model in simulating a large area covering the West Pacific Ocean, China's Mainland, and the East Indian Ocean is very important to improve prediction of the East Asian monsoon climate. The objective of this study is to identify a reasonable configuration of physical parameterization schemes to simulate the precipitation and temperature in this large area. The Mellor-Yamada-Janjic （MYJ） and Yonsei University （YSU） PBL schemes, the WSM3 and WSM5 microphysics schemes, and the Betts-Miller-Janjic （BMJ） and Tiedtke cumulus schemes are compared through simulation of the regional climate of summer 2008. All cases exhibit a similar spatial distribution of temperature as observed, and the spatial correlation coefficients are all higher than 0.95. The cases combining MY J, WSM3/WSM5, and BMJ have the smallest biases of temperature. The choice of PBL scheme has a significant effect on precipitation in such a large area. The cases with MYJ reproduce a better distribution of rain belts, while YSU strongly overestimates the precipitation intensity. The precipitation simulated using WSM3 is similar to that using WSM5. The BMJ cumulus scheme combined with the MYJ PBL scheme has a smaller bias of precipitation. However, the Tiedtke scheme reproduces the precipitation pattern better, especially over the ITCZ.

关键词： wrf model precipitation temperature PBL scheme microphysics scheme cumulus parameterizationscheme

The Impacts of Topography on Spatial and Temporal Rainfall Distribution over Rwanda Based on wrf model

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Atmospheric and Climate Sciences 2016年第2期6卷 145-157页

作者： Didier Ntwali Bob Alex Ogwang Victor Ongoma Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China University of Chinese Academy of Sciences Beijing China Rwanda Meteorology Agency Ministry of Natural Resources (MINIRENA) Kigali Rwanda Nanjing University of Information Science and Technology Nanjing China Uganda National Meteorological Authority Kampala Uganda

The impact of topography on heavy rainfall during two rain seasons was investigated in order to explain their mechanisms on rainfall distribution over Rwanda. Weather Research and Forecasting (wrf-ARW) model was used to study two historical cases of heavy rainfall which took place over Rwanda during two rain seasons, March to May (MAM) and September to December (SOND), from April 7 to 9, 2012 (for MAM) and from October 29 to 31, 2012 (during SOND). The control experiment was done with actual topography, whereas sensitivity experiment was carried out with topography reduced by half. Results show that rainfall distribution over Rwanda significantly changes when topography is reduced. The reduction in topography leads to a decrease in rainfall amounts in both MAM and SOND seasons, with varying magnitudes. This reveals the importance of orography in determining rainfall amounts and distribution over the region. The accumulated rainfall amount from wrf underestimate or overestimate rain gauge stations data by region and by season, but there is good agreement especially in altitude below 1490 m and above 1554 m during April and October respectively. The results may motivate modelling carters to further improve parameterization schemes in the mountainous regions.

关键词： Topography Seasonal Rainfall Rwanda wrf model

Wind Power Assessment Based on the wrf model

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Wind Power Assessment Based on the WRF Model