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A Physics-informed Deep-learning Intensity Prediction Scheme for Tropical Cyclones over the Western North Pacific

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Advances in Atmospheric Sciences 2024年第7期41卷 1391-1402页

作者： Yitian ZHOU Ruifen ZHAN Yuqing WANG Peiyan CHEN zhemin tan Zhipeng XIE Xiuwen NIE Department of Atmospheric and Oceanic Sciences&Institute of Atmospheric Sciences Fudan UniversityShanghai 200438China Shanghai Typhoon Institute of China Meteorological Administration Shanghai 200030China Department of Atmospheric Sciences and International Pacific Research Center University of Hawaii at ManoaHonolulu 96822USA Key Laboratory of Mesoscale Severe Weather/MOE and School of the Atmospheric SciencesNanjing UniversityNanjing 210023China School of Computer Science Fudan UniversityShanghai 200438China

Accurate prediction of tropical cyclone(TC)intensity is challenging due to the complex physical processes involved.Here,we introduce a new TC intensity prediction scheme for the western North Pacific(WNP)based on a time-dependent theory of TC intensification,termed the energetically based dynamical system(EBDS)model,together with the use of a long short-term memory(LSTM)neural network.In time-dependent theory,TC intensity change is controlled by both the internal dynamics of the TC system and various environmental factors,expressed as environmental dynamical efficiency.The LSTM neural network is used to predict the environmental dynamical efficiency in the EBDS model trained using besttrack TC data and global reanalysis data during 1982–2017.The transfer learning and ensemble methods are used to retrain the scheme using the environmental factors predicted by the Global Forecast System(GFS)of the National Centers for Environmental Prediction during 2017–21.The predicted environmental dynamical efficiency is finally iterated into the EBDS equations to predict TC intensity.The new scheme is evaluated for TC intensity prediction using both reanalysis data and the GFS prediction data.The intensity prediction by the new scheme shows better skill than the official prediction from the China Meteorological Administration(CMA)and those by other state-of-art statistical and dynamical forecast systems,except for the 72-h forecast.Particularly at the longer lead times of 96 h and 120 h,the new scheme has smaller forecast errors,with a more than 30%improvement over the official forecasts.

关键词： tropical cyclones western North Pacific intensity prediction EBDS LSTM

Preface to the Special Issue on the 14th International Conference on Mesoscale Convective Systems and High-Impact Weather

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Advances in Atmospheric Sciences 2023年第5期40卷 745-746页

作者： zhemin tan Qinghong ZHANG Xudong LIANG Kun ZHAO Xin XU Lili LEI Key Laboratory of Mesoscale Severe Weather Ministry of Educationand School of Atmospheric SciencesNanjing UniversityNanjing 210063China Department of Atmospheric and Oceanic Sciences School of PhysicsPeking UniversityBeijing 100871China State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China

A mesoscale convective system(MCS)is an organized cluster of thunderstorms known to be the most important convective mode in causing disastrous high-impact weather,such as heavy rainfall,hail,damaging winds,and tornadoes.The small spatial scale and fast temporal evolution of MCSs make their observation and prediction very challenging.East Asia is home to the world’s most prominent monsoon,setting the stage for various severe convective weather events.MCSs and their associated high-impact weather have long been critical issues of concern;as such,their research efforts are valued by governments in East Asia.

关键词： weather convective winds

超强台风“舒力基”(2021)的尺度可预报性

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南京大学学报（自然科学版） 2024年第2期60卷 218-229页

作者：黄雨婧谈哲敏中尺度灾害性天气教育部重点实验室南京大学大气科学学院南京210023

台风尺度表征了台风低层风场特定风速半径大小,是台风灾害影响范围的重要度量.针对超强台风“舒力基”(2021),对其尺度可预报性进行初步探讨.结果表明,模式可以模拟出台风发展初期台风尺度(内核尺度RMW、外围尺度R17)的演变趋势.基于集... 详细信息

台风尺度表征了台风低层风场特定风速半径大小,是台风灾害影响范围的重要度量.针对超强台风“舒力基”(2021),对其尺度可预报性进行初步探讨.结果表明,模式可以模拟出台风发展初期台风尺度(内核尺度RMW、外围尺度R17)的演变趋势.基于集合预报的模拟试验,具体分析了内核尺度RMW、外围尺度R17演变及其误差增长特征.台风预报总体误差主要出现在对流层下层850 h Pa,距离台风中心50~150 km.从初始环境场看,初始相对湿度是影响台风尺度误差增长的重要因子,初始高湿环境有利于台风发展阶段的台风尺度高离散度,从而限制了台风尺度的可预报性.在一定程度上,外围风圈半径的可预报性要高于内核风圈半径.

关键词：台风内核尺度外围尺度可预报性环境湿度

Convective Initiation by Topographically Induced Convergence Forcing over the Dabie Mountains on 24 June 2010

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Advances in Atmospheric Sciences 2016年第10期33卷 1120-1136页

作者： Qiwei WANG Ming XUE zhemin tan Key Laboratory of Mesoscale Severe Weather and School of Atmospheric Sciences Nanjing University Center for Analysis and Prediction of Storms and School of Meteorology University of Oklahoma

The initiation of convective cells in the late morning of 24 June 2010 along the eastward extending ridge of the Dabie Mountains in the Anhui region, China, is studied through numerical simulations that include local data assimilation. A primary convergence line is found over the ridge of the Dabie Mountains, and along the ridge line several locally enhanced convergence centers preferentially initiate convection. Three processes responsible for creating the overall convergence pattern are identified. First, thermally-driven upslope winds induce convergence zones over the main mountain peaks along the ridge, which are shifted slightly downwind in location by the moderate low-level easterly flow found on the north side of a Mei-yu front. Second, flows around the main mountain peaks along the ridge create further convergence on the lee side of the peaks. Third, upslope winds develop along the roughly north-south oriented valleys on both sides of the ridge due to thermal and dynamic channeling effects, and create additional convergence between the peaks along the ridge. The superposition of the above convergence features creates the primary convergence line along the ridge line of the Dabie Mountains. Locally enhanced convergence centers on the primary line cause the initiation of the first convection cells along the ridge. These conclusions are supported by two sensitivity experiments in which the environmental wind （dynamic forcing） or radiative and land surface thermal forcing are removed, respectively. Overall, the thermal forcing effects are stronger than dynamic forcing given the relatively weak environmental flow.

关键词： Dabie Mountains convective initiation low-level convergence line thermal forcing dynamic forcing

An evaluation and improvement of tropical cyclone prediction in the western North Pacific basin from global ensemble forecasts

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Science China Earth Sciences 2020年第1期63卷 12-26页

作者： Lili LEI Yangjinxi GE zhemin tan Xuwei BAO Key Laboratory of Mesoscale Severe Weather/Ministry of Education School of Atmospheric SciencesNanjing UniversityNanjing 210023China Shanghai Typhoon Institute China Meteorological Administration School of Atmospheric SciencesNanjing UniversityNanjing 210023China

Forecasts of tropical cyclones(TCs) of the western North Pacific basin during the period of July to August 2018,especially of Rumbia(2018), Ampil(2018) and Jongdari(2018) that made landfall over Shanghai, have opposed great challenges for numerical models and forecasters. The predictive skill of these TCs are analyzed based on ensemble forecasts of ECMWF and NCEP. Results of the overall performance show that ensemble forecasts of ECMWF generally have higher predictive skill of track and intensity forecasts than those of NCEP. Specifically, ensemble forecasts of ECMWF have higher predictive skill of intensity forecasts for Rumbia(2018) and Ampil(2018) than those of NCEP, and both have low predictive skill of intensity forecasts for Jongdari(2018) at peak intensity. To improve the predictive skill of ensemble forecasts for TCs, a method that estimates adaptive weights for members of an ensemble forecast is proposed. The adaptive weights are estimated based on the fit of ensemble priors and posteriors to observations. The performances of ensemble forecasts of ECMWF and NCEP using the adaptive weights are generally improved for track and intensity forecasts. The advantages of the adaptive weights are more prominent for ensemble forecasts of ECMWF than for those of NCEP.

关键词： Tropical cyclone Ensemble forecast Adaptive weight

Preface to the Special Issue:Climate Change and Variability of Tropical Cyclone Activity

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Advances in Atmospheric Sciences 2022年第2期39卷 203-204页

作者： Liguang WU Bin WANG Johnny CLCHAN Kyung-Ja HA Il-Ju MOON Jun MATSUMOTO zhemin tan Ke FAN Department of Atmospheric and Oceanic Sciences Fudan UniversityShanghai 200438China International Pacific Research Center School of Ocean and Earth Science and TechnologyUniversity of HawaiiHonoluluHI 96822USA School of Energy and Environment City University of Hong KongHong KongChina Research Center for Climate Sciences Pusan National UniversityBusan 46241South Korea Typhoon Research Center Jeju National UniversityJeju 63243South Korea Research Center for Climatology Department of GeographyTokyo Metropolitan UniversityTokyo 192-0392Japan School of Atmospheric Sciences Nanjing UniversityNanjing 210023China School of Atmospheric Sciences Sun Yat-Sen UniversityZhuhai 519082China

Tropical cyclones(TCs) are one of the most destructive natural phenomena on Earth in terms of human-life and economic losses. It is currently a matter of prodigious public and scientific interest how TC activity has changed and will change in a warming climate. This special issue focuses on a challenging subject raised in the Intergovernmental Panel on Climate Change(IPCC) report and numerous research papers.

关键词： warming Earth raised

A Case Study of the Initiation of Parallel Convective Lines Back-Building from the South Side of a Mei-yu Front over Complex Terrain

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Advances in Atmospheric Sciences 2021年第5期38卷 717-736页

作者： Qiwei WANG Yi ZHANG Kefeng ZHU zhemin tan Ming XUE Key Laboratory of Mesoscale Severe Weather and School of Atmospheric Sciences Nanjing UniversityNanjing 210023China Center for Analysis and Prediction of Storms and School of Meteorology University of OklahomaNormanOK 73072USA

Parallel back-building convective lines are often observed extending to the southwest of some mesoscale convective systems(MCSs)embedded in the mei-yu front in China.The convective lines with echo training behavior can quickly develop into a stronger convective group of echoes,resulting in locally heavy rainfall within the mei-yu front rainband.The initiation mechanism of the back-building convective lines is still unclear and is studied based on high-resolution numerical simulation of a case that occurred during 27−28 June 2013.In the present case,the new convection along the convective lines was found to be forced by nonuniform interaction between the cold outflow associated with the mei-yu front MCSs and the warm southerly airflow on the south side of the mei-yu front,which both are modified by local terrain.The mei-yu front MCSs evolved from the western to the eastern side of a basin surrounded by several mesoscale mountains and induced cold outflow centered over the eastern part of the basin.The strong southwest airflow ahead of the mei-yu front passed the Nanling Mountains and impacted the cold outflow within the basin.The nonuniform interaction led to the first stage of parallel convective line formation,in which the low mountains along the boundary of the two airflows enhanced the heterogeneity of their interaction.Subsequently,the convective group quickly developed from the first stage convective lines resulted in apparent precipitation cooling that enhanced the cold outflow and made the cold outflow a sharp southward windshift.The enhanced cold outflow pushed the warm southerly airflow southward and impacted the mountains on the southeast side of the basin,where the roughly parallel mountain valleys or gaps play a controlling role in a second stage formation of parallel convective lines.

关键词： back-building convective line convective initiation complex terrain mei-yu front

Review of Chinese atmospheric science research over the past 70 years: Synoptic meteorology

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Science China Earth Sciences 2019年第12期62卷 1946-1991页

作者： Zhiyong MENG Fuqing ZHANG Dehai LUO zhemin tan Juan FANG Jianhua SUN Xueshun SHEN Yunji ZHANG Shuguang WANG Wei HAN Kun ZHAO Lei ZHU Yongyun HU Huiwen XUE Yaping MA Lijuan ZHANG Ji NIE Ruilin ZHOU Sa LI Hongjun LIU Yuning ZHU Department of Atmospheric and Oceanic Sciences Peking UniversityBeijing 100871China Department of Meteorology and Atmospheric Science The Pennsylvania State UniversityUniversity ParkPA 16802USA Institute of Atmospheric Physics Chinese Academy of SciencesBeijing 100029China School of Atmospheric Science Nanjing UniversityNanjing 210093China National Meteorological Center Beijing 100081China School of Atmospheric Sciences Nanjing University of Information Science and TechnologyNanjing 210044China

Synoptic meteorology is a branch of meteorology that uses synoptic weather observations and charts for the diagnosis,study,and forecasting of weather.Weather refers to the specific state of the atmosphere near the Earth’s surface during a short period of time.The spatial distribution of meteorological elements in the atmosphere can be represented by a variety of transient weather phenomena,which are caused by weather systems of different spatial and temporal scales.Weather is closely related to people’s life,and its development and evolution have always been the focus of atmospheric scientific research and operation.The development of synoptic meteorology is closely related to the development of observation systems,dynamical theories and numerical models.In China,observation networks have been built since the early 1950 s.Up to now,a comprehensive meteorological observation systembased on ground,air and space has been established.In particular,the development of a new generation of dense radar networks,the development of the Fengyun satellite series and the implementation of a series of large field experiments have brought our understanding of weather from large-scale environment to thermal dynamics,cloud microphysical structure and evolution characteristics of meso and micro-scale weather systems.The development of observation has also promoted the development of theory,numerical model and simulation.In the early days,China mainly used foreign numerical models.Lately,China has developed numerical model systems with independent intellectual property rights.Based on the results of high-resolution numerical simulations,in-depth understanding of the initiation and evolution mechanism and predictability of weather at different scales has been obtained.Synoptic meteorology has gradually changed from an initially independent development to a multidisciplinary approach,and the interaction between weather and the change of climate and environment has become a hot and frontier topic in atmospheric science.This paper revie

关键词： Atmospheric sciences Synoptic meteorology Weather 70-year progresses

Effects of Vertical Wind Shear on Intensity and Rainfall Asymmetries of Strong Tropical Storm Bilis (2006)

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Advances in Atmospheric Sciences 2010年第3期27卷 552-561页

作者：余锦华谈哲敏 Key Laboratory of Mesoscale Severe Weather/Ministry of Education and School of Atmospheric SciencesNanjing University School of Atmospheric Sciences Nanjing University of Information Science and Technology

The effects of environmental vertical wind shear （VWS） on the intensity and rainfall asymmetries in Tropical Storm （TS） Bilis （2006） have been analyzed based on TRMM/TMI-estimated surface rainfall data, QuikSCAT wind fields, 850- and 200-hPa winds of the NCEP-NCAR reanalysis, precipitation data at 5-min intervals from automatic weather stations over China's Mainland, and the best track data of TS Bilis （2006）. The results show that the simultaneous and 6-hour-lagged correlation coefficients between VWS and storm intensity （the minimum central sea level pressure） are 0.59145 and 0.57438 （P 〈0.01）, respectively. The averaged VWS was found to be about 11 m s-1 and thus suppressed the intensification of Bilis （2006）. Distribution of precipitation in Bilis （2006） was highly asymmetric. The azimuthally-averaged rainfall rate in the partial eyewall, however, was smaller than that in a major outer rainband. As the storm intensified, the major rainband showed an unusual outward propagation. The VWS had a great impact on the asymmetric distribution of precipitation. Consistent with previous modeling studies, heavy rainfall generally occurred downshear to downshear-left of the VWS vector both near and outside the eyewall, showing a strong wavenumber-one asymmetry, which was amplified as the VWS increased.

关键词： vertical wind shear tropical storm rainfall distribution