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Environmental Conditions Conducive to the Formation of Multiple Tropical Cyclones over the Western North Pacific

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Advances in Atmospheric Sciences 2024年第10期41卷 2027-2042页

作者： Yining GU Ruifen ZHAN Xiaomeng LI Department of Atmospheric and Oceanic Sciences/institute of Atmospheric Sciences Fudan University CMA-FDU Joint Laboratory of Marine meteorology institute of Desert and meteorology China Meteorological Administration

There is limited understanding regarding the formation of multiple tropical cyclones(MTCs). This study explores the environmental conditions conducive to MTC formation by objectively determining the atmospheric circulation patterns favorable for MTC formation over the western North Pacific. Based on 199 MTC events occurring from June to October 1980–2020, four distinct circulation patterns are identified: the monsoon trough(MT) pattern, accounting for 40.3% of occurrences, the confluence zone(CON) pattern at 26.2%, the easterly wave(EW) pattern at 17.8%, and the monsoon gyre(MG) pattern at 15.7%. The MT pattern mainly arises from the interaction between the subtropical high and the monsoon trough, with MTCs forming along the monsoon trough and its flanks. The CON pattern is affected by the subtropical high,the South Asian high, and the monsoon trough, with MTCs emerging at the confluence zone where the prevailing southwesterly and southeasterly flows converge. The EW pattern is dominated by easterly flows, with MTCs developing along the easterly wave train. MTCs in the MG pattern arise within a monsoon vortex characterized by strong southwesterly flows. A quantitative analysis further indicates that MTC formation in the MT pattern is primarily governed by mid-level vertical velocity and low-level vorticity, while mid-level humidity and vertical velocity are significantly important in the other patterns. The meridional shear and convergence of zonal winds are essential in converting barotropic energy from the basic flows to disturbance kinetic energy, acting as the primary source for eddy kinetic energy growth.

关键词： barotropic energy conversion circulation pattern monsoon trough multiple tropical cyclones western North Pacific

Assessment of Seasonal Rainfall Prediction in Ethiopia: Evaluating a Dynamic Recurrent Neural Network to Downscale ECMWF-SEAS5 Rainfall

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Advances in Atmospheric Sciences 2024年第11期41卷 2230-2244页

作者： Abebe KEBEDE Kirsten WARRACH-SAGI Thomas SCHWITALLA Volker WULFMEYER Tesfaye ABEBE Markos WARE Hawassa University College of Agriculture P.O.Box 05HawassaEthiopia institute of Physics and meteorology University of HohenheimP.O.Box 70599StuttgartGermany Arba Minch University water institute of Technology Faculty of Meteorology and HydrologyP.O.Box 21Arba MinchEthiopia

Seasonal rainfall plays a vital role in both environmental dynamics and decision-making for rainfed agriculture in Ethiopia, a country often impacted by extreme climate events such as drought and flooding. Predicting the onset of the rainy season and providing localized rainfall forecasts for Ethiopia is challenging due to the changing spatiotemporal patterns and the country's rugged topography. The Climate Hazards Group Infra Red Precipitation with Station Data(CHIRPS), ERA5-Land total precipitation and temperature data are used from 1981–2022 to predict spatial rainfall by applying an artificial neural network(ANN). The recurrent neural network(RNN) is a nonlinear autoregressive network with exogenous input(NARX), which includes feed-forward connections and multiple network layers, employing the Levenberg Marquart algorithm. This method is applied to downscale data from the European Centre for Medium-range Weather Forecasts fifth-generation seasonal forecast system(ECMWF-SEAS5) and the Euro-Mediterranean Centre for Climate Change(CMCC) to the specific locations of rainfall stations in Ethiopia for the period 1980–2020. Across the stations, the results of NARX exhibit strong associations and reduced errors. The statistical results indicate that, except for the southwestern Ethiopian highlands, the downscaled monthly precipitation data exhibits high skill scores compared to the station records, demonstrating the effectiveness of the NARX approach for predicting local seasonal rainfall in Ethiopia's complex terrain. In addition to this spatial ANN of the summer season precipitation, temperature, as well as the combination of these two variables, show promising results.

关键词： station prediction downscaling artificial neural networks rainfall

Sensitivity Simulations of the 30 March 2020 Xichang Wildfire in Southwest China Based on the WRF-Fire Model

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Journal of Meteorological Research 2024年第4期38卷 826-843页

作者： Yujue LIU Shiguang MIAO Hanbin ZHANG institute of Urban meteorology China Meteorological AdministrationBeijing 100089 Key Laboratory of Urban meteorology China Meteorological AdministrationBeijing 100089

This paper describes a fire forecast system—Weather Research and Forecasting-Fire(WRF-Fire)—that is employed to simulate a real wildfire case in Xichang,Sichuan Province,Southwest China on 30 March 2020 at a 100-m resolution over the fire area,in order to provide a fine representation of the terrain and fuel heterogeneities and explicitly resolve the atmospheric *** sensitivity experiments were conducted to analyze the impacts of atmospheric model grid spacing and fire–atmosphere interaction on simulated meteorological fields and fire *** results indicate that finer horizontal grid spacing in the atmospheric model improves the accuracy of wind,temperature,and moisture simulations in the near surface ***,it can better describe local wind field characteristics,capture microscale wind speed fluctuations,and produce more significant effect from fire–atmosphere *** mass and energy released by the fire model and its feedback to the atmospheric model exhibit enhanced heterogeneous *** simulated fire area aligns well with the observation,with KAPPA coefficient(KC)of 0.56–0.59 and spatial correlation coefficient(SC) of 0.52–*** this real case,the influence of heterogeneous land surface on the fire behavior is much greater than the atmosphere–fire *** study suggests that WRFFire holds high potential as a real wildfire simulation tool,offering a new and feasible approach for fire prediction.

关键词： Weather Research and Forecasting-Fire wildfire coupled fire–atmosphere modeling fire behavior large-eddy simulation(LES)

Changes of tropical cyclone size in three oceanic basins of the northern hemisphere from 2001 to 2021

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Frontiers of Earth Science 2024年第2期18卷 312-323页

作者： Banglin ZHANG Jeremy Cheuk-Hin LEUNG Shengyuan LIU Jianjun XU Guangzhou institute of Tropical and Marine meteorology/Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction CMAGuangzhou 510640China College of Atmospheric Science Lanzhou UniversityLanzhou 730020China College of Ocean and meteorology Guangdong Ocean UniversityZhanjiang 524088China CMA-GDOU Joint Laboratory for Marine meteorology&South China Sea institute of Marine meteorology Guangdong Ocean UniversityZhanjiang 524088China

In this study the changes of tropical cyclone(TC)size from 2001 to 2021 are analyzed based on linear and quadratic curve fittings of the National Hurricane Center(NHC)/Joint Typhoon Warning Center(JTWC)best track data,based on the radius of maximum wind(RMW)and the average radius of 34-kt wind(AR34),in three oceanic basins of the North Atlantic(NATL),the Western North Pacific(WPAC)and the Eastern North Pacific(EPAC).The computations are done separately for two categories of tropical cyclones:tropical storms(TS)and hurricanes(HT).Size changes of landfalling and non-landfalling TCs are also *** show that there is a great inter-basin variability among the changes in TC *** conclusions include:1)overall,the inner cores of TSs have become larger in all three basins,with the increasing tendencies being significant in the NATL and WAPC,while those of HTs mostly get smaller or remain similar;2)meanwhile,comparatively large inter-basin differences are observed for the TC outer core sizes,and the sizes of landfalling TCs;3)particularly,a significant decrease in landfalling HT outer core size is observed over the EPAC;4)in contrast,significant increases in landfalling TS inner core size are found over the NATL and *** presented analysis results could benefit future research about TC forecasts,storm surge studies,and the cyclone climate and its changes.

关键词： tropical cyclone storm size frequency intensity duration

Combinatorial Optimization of Physics Parameterization Schemes for Typhoon Simulation Based on a Simple Genetic Algorithm(SGA)

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Journal of Meteorological Research 2024年第1期38卷 10-26页

作者： Zebin LU Jianjun XU Zhiqiang CHEN Jinyi YANG Jeremy Cheuk-Hin LEUNG Daosheng XU Banglin ZHANG China Meteorological Administration–Guangdong Ocean University Joint Laboratory for Marine meteorology South China Sea Institute of Marine MeteorologyGuangdong Ocean UniversityZhanjiang 524088 College of Ocean and meteorology Guangdong Ocean UniversityZhanjiang 524088 Guangzhou institute of Tropical and Marine meteorology/Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction China Meteorological AdministrationGuangzhou 510640 Shenzhen institute of Guangdong Ocean University Shenzhen 518120 College of Atmospheric Science Lanzhou UniversityLanzhou 730000

Each physical process in a numerical weather prediction(NWP)system may have many different parameterization *** studies have shown that the performance of different physical parameterization schemes varies with the weather situation to be ***,it is necessary to select a suitable combination of physical parameterization schemes according to the variation of weather ***,it is rather difficult to identify an optimal combination among millions of possible parameterization scheme *** study applied a simple genetic algorithm(SGA)to optimizing the combination of parameterization schemes in NWP models for typhoon *** feasibility of SGA was verified with the simulation of Typhoon Mujigae(2015)by using the Weather Research and Forecasting(WRF)model and Typhoon Higos(2020)by using the Coupled Ocean–Atmosphere–Wave–Sediment Transport(COAWST)modeling *** results show that SGA can efficiently obtain the optimal combination of *** Typhoon Mujigae(2015),the optimal combination can be found from the 1,304,576 possible combinations by running only 488 *** results can be obtained for Typhoon Higos(2020).Compared to the default combination proposed by the COAWST model system,the optimal combination scheme significantly improves the simulation of typhoon track and *** study provides a feasible way to search for the optimal combinations of physical parameterization schemes in WRF and COAWST for more accurate typhoon *** can help provide references for future development of NWP models,and for analyzing the coordination and adaptability of different physical process parameterization schemes under specific weather backgrounds.

关键词： simple genetic algorithm(SGA) combinatorial optimization typhoon forecast numerical weather prediction(NWP)

Community-Level Practice Checklists for Health Protection During Cold Spells in China

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China CDC weekly 2024年第5期6卷 83-87页

作者： Jing Shang Mengzhen Zhao Zhao Liu Xiya Zhang Shiguang Miao Ishaq D.Sulaymon Wenjia Cai institute of Urban meteorology CMABeijingChina School of management and Economics Beijing Institute of TechnologyBeijingChina School of Airport Economics and management Beijing Institute of Economics and ManagementBeijingChina Department of Earth System Science Tsinghua UniversityBeijingChina Sand and Dust Storm Warning Regional Center National Center for MeteorologyJeddahSaudi Arabia Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control Collaborative Innovation Center of Atmospheric Environment and Equipment TechnologySchool of Environmental Science and EngineeringNanjing University of Information Science and TechnologyNanjing CityJiangsu ProvinceChina

Communities play a crucial role in protecting the health of vulnerable populations such as the elderly,low-income groups,and high-risk individuals during cold ***,current strategies for responding to cold spells primarily consist of programmatic policies that lack practicality,specificity,and detailed implementation guidelines for community ***,this study aims to identify and analyze the challenges faced by communities in responding to cold spells,review international experiences,and develop a set of practical checklists for community-level health *** checklists will assist community workers and volunteers in effectively preparing for,responding to,and recovering from cold spells.

关键词： preparing income primarily

Impact of the Complex Terrain in Beijing on Formation of Low-Level Jets

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Journal of Meteorological Research 2024年第1期38卷 138-150页

作者： Li’ao ZHOU Chenggang WANG Shiguang MIAO Ju LI School of Atmospheric Physics Nanjing University of Information Science&TechnologyNanjing 210044 institute of Urban meteorology China Meteorological AdministrationBeijing 100089 Key Laboratory of Urban meteorology China Meteorological AdministrationBeijing 100089

This study investigated how the Taihang Mountains and the Yanshan Mountains affect low-level jets(LLJs)in the Beijing area,based on conventional radiosonde observations from Nanjiao Observatory(2016–2017)and high-resolution Weather Research and Forecasting–Advanced Research WRF(WRF-ARW)model *** of radiosonde observations indicated that LLJs in the study area are mainly from the southwest and northwest directions,with occurrence frequency of 44.6%and 33.0%,***(northwest)LLJs are aligned parallel(perpendicular)to the orientation of the Taihang Mountain *** sensitivity experiments using the WRF-ARW model were then conducted to examine the effects of terrain forcing on the northwest and southwest LLJs,with adopted terrain heights of 100%and 50%.The results showed that for northwest LLJs,reduction in the elevation of the Taihang Mountain Range led to weakening of jet intensity by approximately 20%and reduction in jet maximum height by approximately 250 m;lowering the Yanshan Mountain Range had minor influence on the northwest LLJs,with only a 5.2%reduction in intensity and no substantial change in jet maximum *** southwest LLJs,reduction in the elevation of both the Taihang and Yanshan Mountain ranges resulted in minor changes in the intensity and height of the *** analysis revealed that the topography in the Beijing area could modulate the height and intensity of the stable layer by altering the inversion structure within the boundary *** LLJs can develop rapidly within the stable layer,and both the location and the scale of the jet core exhibited reasonable agreement with the extent of the stable layer.

关键词： low-level jets(LLJs) mesoscale numerical simulation terrain forcing

Impact of Local Climate Zones on the Urban Heat and Dry Islands in Beijing:Spatial Heterogeneity and Relative Contributions

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Journal of Meteorological Research 2024年第1期38卷 126-137页

作者： Zuofang ZHENG Fu LUO Nana LI Hua GAO Yuanjian YANG institute of Urban meteorology China Meteorological AdministrationBeijing 100089 School of Atmospheric Physics Nanjing University of Information Science&TechnologyNanjing 210044 Key Laboratory of Urban meteorology China Meteorological AdministrationBeijing 100089

Based on the building height and density data on a 100-m resolution,hourly 2-m temperature and humidity data at83 automatic weather stations,and gridded local climate zone(LCZ)data on a 120-m resolution in urban Beijing in2020,this study first employs the semivariogram combined with building parameters to calculate spatial correlations and has identified an LCZ grid resolution of 500 m suitable for best usage of the available observation ***,how the spatially heterogeneous LCZs affect and contribute to the canopy urban heat island intensity(UHII)and urban dry island intensity(UDII)are quantitatively *** is found that UHII is high in winter and low in summer with a unimodal diurnal variation while UDI is low in winter but high in summer with a bimodal diurnal *** LCZ with compact mid-rise(open high-rise)buildings exhibits the highest UHII(UDII),followed by the compact high-rise(compact low-rise),while the LCZ of scattered trees presents both the lowest UHII and the lowest *** most significant difference in the UHII(UDII)among the nine LCZ types in the urban area of Beijing is2.62℃(1.1 g kg^(-1)).Area-weighted averaging analysis reveals that the open mid-rise LCZ is the most significant contributor to the UHII(UDII),immediately followed by compact mid-rise(open low-rise),with the least contribution from bare rock or paved(scattered trees).The results also indicate that beyond the intrinsic physical properties of the LCZs of a city,their area proportions cannot be overlooked in evaluating their impact on the UHI and *** quantitatively findings could help urban planners to create a livable urban climate and environment by adjusting the relevant land use.

关键词： local climate zone(LCZ) urban heat island(UHI) urban dry island(UDI) distribution pattern contribution rate Beijing

Multimodel Ensemble Forecast of Global Horizontal Irradiance at PV Power Stations Based on Dynamic Variable Weight

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Journal of Tropical meteorology 2024年第3期30卷 327-336页

作者： YUAN Bin SHEN Yan-bo DENG Hua YANG Yang CHEN Qi-ying YE Dong MO Jing-yue YAO Jin-feng LIU Zong-hui Public Meteorological Service Center China Meteorological AdministrationBeijing 100081 China Key Laboratory of Energy meteorology China Meteorological AdministrationBeijing 100081 China Guangzhou institute of Tropical and Marine meteorology China Meteorological AdministrationGuangzhou 510641 China institute of Urban meteorology China Meteorological AdministrationBeijing 100089 China Center for Earth System Modeling and Prediction China Meteorological AdministrationBeijing 100081 China institute of Desert meteorology China Meteorological AdministrationUrumqi 830002 China

In the present study,multimodel ensemble forecast experiments of the global horizontal irradiance(GHI)were conducted using the dynamic variable weight *** study was based on the forecasts of four numerical models,namely,the China Meteorological Administration Wind Energy and Solar Energy Prediction System,the Mesoscale Weather Numerical Prediction System of China Meteorological Administration,the China Meteorological Administration Regional Mesoscale Numerical Prediction System-Guangdong,and the Weather Research and Forecasting Model-Solar,and observational data from four photovoltaic(PV)power stations in Yangjiang City,Guangdong *** results show that compared with those of the monthly optimal numerical model forecasts,the dynamic variable weight-based ensemble forecasts exhibited 0.97%-15.96%smaller values of the mean absolute error and 3.31%-18.40%lower values of the root mean square error(RMSE).However,the increase in the correlation coefficient was not ***,the multimodel ensemble mainly improved the performance of GHI forecasts below 700 W m-2,particularly below 400 W m-2,with RMSE reductions as high as 7.56%-28.28%.In contrast,the RMSE increased at GHI levels above 700 W *** for the key period of PV power station output(02:00-07:00),the accuracy of GHI forecasts could be improved by the multimodel ensemble:the multimodel ensemble could effectively decrease the daily maximum absolute error(AE max)of GHI ***,with increasing forecasting difficulty under cloudy conditions,the multimodel ensemble,which yields data closer to the actual observations,could simulate GHI fluctuations more accurately.

关键词： GHI forecast multimodel ensemble dynamic variable weight PV power station