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Journal of Environmental Sciences 2024年第6期140卷 319-330页

作者： Zhouxiang Cai Liting Hu Di Chen Ying Zhang Xuekun Fang College of Environmental&Resource Sciences Zhejiang UniversityHangzhou 310058China Center for Global Change Science Massachusetts Institute of TechnologyCambridgeMA 02139United States anji meteorological bureau Anji 313300China

To achieve carbon neutrality,the Chinese government needs to gain a comprehensive understanding of the sources and drivers of greenhouse gas(GHG)emissions,particularly at the county level.anji County in eastern China is a typical example of an industrial transformation from quarrying to a low-carbon economy.This study analyzed the decoupling types and structural characteristics of GHG emissions and the driving factors of carbon dioxide(CO_(2))emissions in the anji from 2006 to 2019,and explored the differences between countylevel and provincial-level or city-level results.It was observed that energy-related activities are the main source of GHG emissions in anji and that economic development is the driving factor behind the increasing CO_(2)emissions.However,industrial transformation and upgradation coupled with the alternative use of clean energy limit the growth of GHG emissions.This study details the GHG emissions of county during the industrial transformation stage and provides corresponding policy recommendations for county governments.

关键词： County GHG emissions Decoupling Driving factors Policy recommendations

Analysis on characteristics of extreme precipitation indices and atmospheric circulation in Northern Shanxi

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Research in Cold and Arid Regions 2024年第2期16卷 84-97页

作者： Xia Cai Yan Song Lin Cai Xin Su GuiHua Liang YanMing Xu Shuozhou meteorological bureau of Shanxi Province China meteorological Administration Training Center Heze University of Shandong Province Huafeng meteorological Media Group Shuocheng meteorological bureau

This article utilizes daily precipitation data from 28 national meteorological stations in northern Shanxi Province spanning from 1972 to 2020, and the US NCEP/NCAR monthly average reanalysis and ERA5 monthly average reanalysis data. The study employs techniques such as empirical orthogonal function(EOF) decomposition, MannKendall mutation and other methods to investigate the spatiotemporal distribution of extreme precipitation index in northern Shanxi and their correlation with atmospheric circulation. The research results show that: the absolute index, relative index, intensity index and sustained dry period index(CDD) in the continuous index appear from southwest to northeast. The spatial distribution characteristics of the central region decrease, while the continuous wet period(CWD) decreases from the central to the east and west. The three indices Rx1day, Rx5day, and CWD mutated in 1978, 1975, and 1983 respectively, and other extreme precipitation indices all appeared in a sudden change from a low-value period to a high-value period occurred around 2010. In the high-value years of the summer extreme precipitation index, there is a significant negative anomaly in the height field in the mid-high latitude regions of Eurasia. Northern Shanxi is controlled by a broad low-pressure trough in the Lake Baikal area.Water vapor transported via the east, west, and south routes converges in the northern Shanxi region and encounters cold air from the north. There is a strong upward motion anomaly at 500 hPa in the troposphere, and the dynamic conditions of upper-level divergence and lower-level convergence lead to more summer extreme precipitation in the northern Shanxi region. Conversely, in the low-value years of the summer extreme precipitation index, northern Shanxi is affected by a strong high-pressure ridge north of Lake Baikal. There is a downward motion anomaly at 500 hPa, and the northern Shanxi region lacks water vapor. The cold and warm air cannot converge, and both the water vapor conditions and dynamic cond

关键词： Northern Shanxi Extreme precipitation indices Spatio-temporal distribution and evolution Mutations Atmospheric circulation anomaly

Microphysical Insights into a Tornadic Supercell from Dual-Polarization Radar Observations in Jiangsu, China on 14 May 2021

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Journal of meteorological Research 2024年第2期38卷 303-320页

作者： Chao YUAN Yang BAI Pengfei SUN Hua BAI Lu XIA China meteorological Administration Tornado Key Laboratory Foshan 528315 Institute of Atmospheric Environment China Meteorological AdministrationShenyang 110166 Panjin National Climate Observatory Panjin 124010 Yangzhou meteorological bureau of Jiangsu Province Yangzhou 225100 Yichun meteorological bureau of Heilongjiang Province Yichun 153000

Tornadoes are incredibly powerful and destructive natural events,yet the microphysical characteristics of the parent storm and its effects on tornadogenesis remain unclear.This study analyzed polarization radar data of a tornadic supercell that occurred in Jiangsu Province of China on 14 May 2021,in comparison with another tornadic supercell and two non-tornadic supercells that occurred in the same region in 2023.The two tornadic supercells exhibited lower differential reflectivity(ZDR)in the hook echo region compared with the non-tornadic supercells,indicating smaller median drop sizes.A distinct increase in ZDR from the melting of frozen hydrometeors,observed between2.5-and 4.0-km altitude in the non-tornadic storms,was absent in the tornadic cases.The non-tornadic supercells also displayed substantially higher specific differential phase(KDP)below the melting level,likely aroused from enhanced melting and cooling.These findings suggest fundamental microphysical contrasts between tornadic and nontornadic supercells.Specifically,tornadic supercells have smaller droplets and may reduce melting in hook echoes.Moreover,greater separation between the ZDR arc and the KDP foot was observed during tornadogenesis.The vertical gradient of KDP related to the cooling pool strength of the hook echo,regulating rear-flank downdraft thermodynamics.Despite the limited number of cases investigated,the findings of this study indicate that monitoring ZDR,KDP,and drop size distribution trends could assist with tornado prediction and warnings.

关键词： tornado polarimetric radar supercell hook echo drop size distribution

An Analysis of the Low Moving Speed of Landfalling Typhoon In-Fa in 2021

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Journal of Tropical Meteorology 2024年第1期30卷 51-60页

作者：郑丽娜吕新刚李瑞 Jinan meteorological bureau of Shandong Province Jinan 250102 China

The movement speed of Typhoon In-Fa(2021)was notably slow,at 10 km h-1or less,for over 20 hours following its landfall in Zhejiang,China,in contrast to other typhoons that have made landfall.This study examines the factors contributing to the slow movement of Typhoon In-Fa,including the steering flow,diabatic heating,vertical wind shear(VWS),and surface synoptic situation,by comparing it with Typhoons Yagi(2018)and Rumbia(2018)which followed similar tracks.The findings reveal that the movement speed of Typhoons Yagi and Rumbia is most closely associated with their respective 500 h Pa environmental winds,with a steering flow of 10^(-12)m s^(-1).In contrast,Typhoon InFa’s movement speed is most strongly correlated with the 850 h Pa environmental wind field,with a steering flow speed of only 2 m s^(-1).Furthermore,as Typhoon In-Fa moves northwest after landfall,its intensity is slightly greater than that of Typhoons Yagi and Rumbia,and the pressure gradient in front of Typhoon In-Fa is notably smaller,leading to its slow movement.Additionally,the precipitation distribution of Typhoon In-Fa differs from that of the other two typhoons,resulting in a weak asymmetry of wavenumber-1 diabatic heating,which indirectly affects its movement speed.Further analysis indicates that VWS can alter the typhoon’s structure,weaken its intensity,and ultimately impact its movement.

关键词： landfalling typhoon steering flow diabatic heating VWS

Comparative Analysis of Energy Characteristics of Two Southwest Vortices in Sichuan Under Similar Circulation Backgrounds

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Journal of Tropical Meteorology 2024年第2期30卷 168-179页

作者：周春花张驹肖红茹 Sichuan meteorological Disaster Prevention Technology Center Chengdu 610072 China Chengdu meteorological bureau Chengdu 610072 China Sichuan meteorological Observatory Chengdu 610072 China

Based on ERA5 reanalysis data,the present study analyzed the thermal energy development mechanism and kinetic energy conversion characteristics of two extreme rainstorm processes in relation to the shallow southwest vortex in the warm-sector during a“rain-generated vortex”process and the deep southwest vortex in a“vortex-generated rain”process.The findings were as follows:(1)During the extreme rainstorm on August 11,2020(hereinafter referred to as the“8·11”process),intense surface heating and a high-energy unstable environment were observed.The mesoscale convergence system triggered convection to produce heavy rainfall,and the release of latent condensation heat generated by the rainfall promoted the formation of a southwest vortex.The significant increase(decrease)in atmospheric diabatic heating and kinetic energy preceded the increase(decrease)in vorticity.By contrast,the extreme rainstorm on August 16,2020(hereinafter referred to as the“8·16”process)involved the generation of southwest vortex in a low-energy and highhumidity environment.The dynamic uplift of the southwest vortex triggered rainfall,and the release of condensation latent heat from rainfall further strengthened the development of the southwest vortex.The significant increase(decrease)in atmospheric diabatic heating and kinetic energy exhibited a delayed progression compared to the increase(decrease)in vorticity.(2)The heating effect around the southwest vortex region was non-uniform,and the heating intensity varied in different stages.In the“8·11”process,the heating effect was the strongest in the initial stage,but weakened during the vortex's development.On the contrary,the heating effect was initially weak in the“8·16”process,and intensified during the development stage.(3)The available potential energy of the“8·11”process significantly increased in kinetic energy converted from rotational and divergent winds through baroclinic action,and the divergent wind energy continued to convert into rotational wind energy.By contrast,the“8·16”process inv

关键词： southwest vortex similar circulation background diabatic heating kinetic energy spatial non-uniform heating effect

Influence of sea-land breeze on the formation and dissipation of severe dense fog and its burst reinforcement in the Yellow Sea coastal area,China

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Science China Earth Sciences 2024年第2期67卷 432-449页

作者： Ya GAO Duanyang LIU Shuqi YAN Wenjun ZHOU Hongbin WANG Fan ZU Qin MEI Chuanxiang YI Ye SHENG Key Laboratory of Transportation Meteorology of China meteorological Administration Nanjing210041China Yancheng meteorological bureau Yancheng224000China Nanjing Joint Institute for Atmospheric Sciences Nanjing210041China Key Laboratory of Disaster Weather Chinese Academy of Meteorological SciencesBeijing100086China

Based on the global reanalysis data of the National Centers for Environmental Prediction(NCEP)/National Center for Atmospheric Research,the surface meteorological observation data,sounding data and satellite observation data,this paper comprehensively analyzes the evolution process and formation mechanism of a persistent severe dense fog process occurred on February 15–17,2015 in Yancheng,eastern China.Through the numerical simulation experiment of Weather Research and Forecast(WRF)model,we further analyze the impact of sea-land breeze on the formation and burst reinforcement of fog.Results show that the precipitation caused by the southwesterly airflow in front of the upper-level trough and the low-pressure inverted trough are conducive to the formation of early rain fog,while the nighttime clear radiance under the control of surface cold high and the infiltration of weak cold advection are conducive to the formation and development of later radiation-advection fog.The WRF model simulates the fog evolution process,which is basically consistent with the actual fog area,and the simulation results are credible to a certain extent.The simulation results show that the establishment of sea breeze has an advection cooling effect on the near surface layer,which is conducive to the formation and development of the inversion layer on the near surface,providing stable stratification conditions for the formation and burst reinforcement of fog.On one hand,the strengthening of sea breeze circulation can continuously transport water vapor to the study area.On the other,the occurrence of ultra-low level jet is favorable for the accumulation of low-level water vapor.At the same time,the inversion intensity further strengthens,which is in favor of the burst reinforcement and long-term maintenance of fog.

关键词： Radiation-advection fog Sea-land breeze Atmospheric boundary layer Fog burst reinforcement WRF model

Evolution Mechanism of a Severe Squall Line Triggered by the Coupling of a Sea Breeze Front and a Gust Front

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Journal of Tropical Meteorology 2024年第2期30卷 200-210页

作者：万夫敬孙敏庞华基赵海军赵传湖 Qingdao meteorological bureau QingdaoShandong 266003 China Shanghai Central meteorological Observatory Shanghai 200030 China Linyi meteorological bureau LinyiShandong 276037 China Frontier Science Center for Deep Ocean Multispheres and Earth System(FDOMES)and Physical Oceanography Laboratory Ocean University of ChinaQingdaoShandong 266101 China

In the present study, a severe squall line(SL) was analyzed by using intensive observational surface data and radar monitoring products. In this process, mesoscale convergence lines, such as the sea breeze front(SBF), gust front and dry line, served as the main triggering and strengthening factors. The transition from convection triggering to the formation of the initial shape was mainly affected by the convergence line of the SBF, which combined with thermal convection to form the main parts of the SL. In the later stage, the convergence line of the gust front merged with other convergence lines to form a series of strong convective cells. The SBF had good indicative significance in terms of severe convective weather warnings. The suitable conditions of heat, water vapor and vertical wind shear on the Shandong Peninsula were beneficial to the maintenance of the SL. Before SL occurrence, tropopause folding strengthened, which consequently enhanced the baroclinic property in the middle and upper troposphere. The high sensible heat flux at the surface easily produced a positive potential vorticity anomaly in the low layer, resulting in convective instability, which was conducive to the maintenance of these processes. In the system, when precipitation particles passed through the unsaturated air layer, they underwent strong evaporation, melting or sublimation, and the cooling effect formed negative buoyancy, which accelerated the sinking of the air and promoted the sustained development of the surface gale. Together with the development of lowlevel mesocyclones, the air pressure decreased rapidly, which was conducive to gale initiation.

关键词： squall line sea breeze front gust front cold pool thunderstorm gale

Improving the Forecasts of Coastal Wind Speeds in Tianjin, China Based on the WRF Model with Machine Learning Algorithms

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Journal of meteorological Research 2024年第3期38卷 570-585页

作者： Weihang ZHANG Meng TIAN Shangfei HAI Fei WANG Xiadong AN Wanju LI Xiaodong LI Lifang SHENG College of Oceanic and Atmospheric Sciences Ocean University of China Tianjin Key Laboratory for Oceanic Meteorology Tianjin Institute of Meteorological Science CMA Earth System Modeling and Prediction Centre China Meteorological Administration (CMA) Qingdao meteorological bureau

Characterized by sudden changes in strength, complex influencing factors, and significant impacts, the wind speed in the circum-Bohai Sea area is relatively challenging to forecast. On the western side of Bohai Bay, as the economic center of the circum-Bohai Sea, Tianjin exhibits a high demand for accurate wind forecasting. In this study, three machine learning algorithms were employed and compared as post-processing methods to correct wind speed forecasts by the Weather Research and Forecast（WRF） model for Tianjin. The results showed that the random forest（RF）achieved better performance in improving the forecasts because it substantially reduced the model bias at a lower computing cost, while the support vector machine（SVM） performed slightly worse（especially for stronger winds）,but it required an approximately 15 times longer computing time. The back propagation（BP） neural network produced an average forecast significantly closer to the observed forecast but insufficiently reduced the RMSE. In regard to wind speed frequency forecasting, the RF method commendably corrected the forecasts of the frequency of moderate（force 3） wind speeds, while the BP method showed a desirable capability for correcting the forecasts of stronger（force > 6） winds. In addition, the 10-m u and v components of wind(u10and v10), 2-m relative humidity（RH2） and temperature（T2）, 925-hPa u(u925), sea level pressure（SLP）, and 500-hPa temperature(T500) were identified as the main factors leading to bias in wind speed forecasting by the WRF model in Tianjin, indicating the importance of local dynamical/thermodynamic processes in regulating the wind speed. This study demonstrates that the combination of numerical models and machine learning techniques has important implications for refined local wind forecasting.

关键词： machine learning Weather Research and Forecast (WRF) model wind speed forecasting coastal region

Character of Convective Systems Producing Short-Term Heavy Precipitation in Central China Revealed by Kilometer and Minute Interval Observations

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Journal of meteorological Research 2024年第3期38卷 530-541页

作者： Zitong CHEN Yunying LI Zhiwei ZHANG Jing SUN Chengzhi YE Anyuan XIONG College of Meteorology and Oceanography National University of Defense Technology High Impact Weather Key Laboratory of China meteorological Administration Unit No.92192 of Chinese People's Liberation Army Hubei Key Research Laboratory for Heavy Rain Monitoring and Warning Institute of Heavy RainChina Meteorological Administration Institute of meteorological Sciences of Hunan Province Hunan Meteorological Bureau National meteorological Information Centre China Meteorological Administration

Accurate forecasting of heavy precipitation in central China is still a challenge, within which a key issue is our still incomplete understanding of the convective systems（CSs） responsible for such events. In this study, through use of an iterative rain-cell tracking algorithm, the macroscale characteristics（scale, intensity, duration, etc.） of the CSs that produced 595 short-term heavy precipitation events in Hunan Province, central China, are quantitatively analyzed,based on radar reflectivity, echo top, and rainfall observations at 1-km and 6-min intervals in April–September of2016–2018. The results show that CSs present significant seasonal and diurnal features. Spring CSs usually cover a larger echo area with stronger convective cores and thus generate more precipitation than summer CSs, though summer CSs develop more vigorously and frequently. CSs initiated at 1400–1600 local time are characterized by the strongest convection and a smaller spatiotemporal scale, causing violent and transient showers with typical areal precipitation of 0.5–1mm km-2, but less total precipitation. Further analyses of the relationships among the scale, intensity, duration, and total precipitation of CSs reveal that the convective intensity is linearly correlated to the spatiotemporal scale of CSs, with the duration increasing on average by 0.0372 h dBZ-1; the echo area is significantly correlated to the total precipitation, and the duration and rainfall amount are connected with the area expansion rate（AER）of CSs: when the AER exceeds 50%, CSs expand rapidly with increasing total precipitation, but the duration is shorter.These findings provide a helpful reference for the forecasting of short-term heavy precipitation induced by CSs in central China.

关键词： convective system radar reflectivity factor total precipitation iterative rain-cell tracking

Characteristics and Mechanisms of Persistent Wet–Cold Events with Different Cold-air Paths in South China

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Advances in Atmospheric Sciences 2024年第6期41卷 1171-1183页

作者： Xiaojuan SUN Li CHEN Chuhan LU Panxing WANG Key Laboratory of meteorological Disaster Ministry of Education/Collaborative Innovation Center on Forecast and Evaluation of Meteorological DisastersNanjing University of Information Science and TechnologyNanjing 210044China School of Atmospheric Sciences Nanjing University of Information Science and TechnologyNanjing 210044China Qianxinan Bouyei and Miao Autonomous Prefecture meteorological bureau of Guizhou Province Xingyi 562400China

We investigate the characteristics and mechanisms of persistent wet–cold events(PWCEs)with different types of coldair paths.Results show that the cumulative single-station frequency of the PWCEs in the western part of South China is higher than that in the eastern part.The pattern of single-station frequency of the PWCEs are“Yangtze River(YR)uniform”and“east–west inverse”.The YR uniform pattern is the dominant mode,so we focus on this pattern.The cold-air paths for PWCEs of the YR uniform pattern are divided into three types—namely,the west,northwest and north types—among which the west type accounts for the largest proportion.The differences in atmospheric circulation of the PWCEs under the three types of paths are obvious.The thermal inversion layer in the lower troposphere is favorable for precipitation during the PWCEs.The positive water vapor budget for the three types of PWCEs mainly appears at the southern boundary.

关键词： persistent wet–cold events cold-air paths circulation characteristics water vapor