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RELATIONSHIPS BETWEEN THE POSITION VARIATION OF THE WEST PACIFIC SUBTROPICAL HIGH AND THE DIABATIC HEATING DURING PERSISTENT INTENSE RAIN EVENTS IN YANGTZE-HUAIHE RIVERS BASIN

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Journal of Tropical Meteorology 2012年第4期18卷 528-536页

作者：王黎娟陈璇管兆勇曾明剑 Key Laboratory of meteorological Disaster of Ministry of Education Nanjing University of Information Science&Technology Wuhan Central meteorological observatory Jiangsu Institute of meteorological Sciences

By using NCEP/NCAR daily reanalysis data and daily precipitation data of 740 stations in China, relationships between the position variation of the West Pacific subtropical high (WPSH) and the diabatic heating during persistent and intense rains in the Yangtze-Huaihe Rivers basin are studied. The results show that the position variation of WPSH is closely associated with the diabatic heating. There are strong apparent heating sources and moisture sinks in both the basin (to the north of WPSH) and the north of Bay of Bengal (to the west of WPSH) during persistent and intense rain events. In the basin, Q 1z begins to increase 3 days ahead of intense rainfall, maximizes 2 days later and then reduces gradually, but it changes little after precipitation ends, thus preventing the WPSH from moving northward. In the north of Bay of Bengal, 2 days ahead of strong rainfall over the basin, Q 1z starts to increase and peaks 1 day after the rain occurs, leading to the westward extension of WPSH. Afterwards, Q 1z begins declining and the WPSH makes its eastward retreat accordingly. Based on the complete vertical vorticity equation, in mid-troposphere, the vertical variation of heating in the basin is favorable to the increase of cyclonic vorticity north of WPSH, which counteracts the northward movement of WPSH and favors the persistence of rainbands over the basin. The vertical variation of heating in the north of Bay of Bengal is in favor of the increase of anti-cyclonic vorticity to the west of WPSH, which induces the westward extension of WPSH.

关键词： west Pacific subtropical high complete vertical vorticity equation persistent heavy rain events overYangtze-Huaihe rivers basin diabatic heating

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Macro-and Micro-physical Characteristics of Different Parts of Mixed Convective-stratiform Clouds and Differences in Their Responses to Seeding

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Advances in Atmospheric Sciences 2022年第12期39卷 2040-2055页

作者： Dejun LI Chuanfeng ZHAO Peiren LI Cao Liu Dianli GONG Siyao LIU Zhengteng YUAN Yingying CHEN Hubei meteorological Service Center Wuhan 430205China College of Global Change and Earth System Science Beijing Normal UniversityBeijing 100875China Weather Modification Office of Shanxi province Taiyuan 030032China Wuhan Central meteorological observatory Wuhan 430074China Weather Modification Office of Shandong province Jinan 250031China

This study investigates the cloud macro-and micro-physical characteristics in the convective and stratiform regions and their different responses to the seeding for mixed convective-stratiform clouds that occurred in Shandong province on 21 May 2018,based on the observations from the aircraft,the Suomi National Polar-Orbiting Partnership(NPP)satellite,and the high-resolution Himawari-8(H8)*** aircraft observations show that convection was deeper and radar echoes were significantly enhanced with higher tops in response to seeding in the convective *** is linked with the conversion of supercooled liquid droplets to ice crystals with released latent heat,resulting in strengthened updrafts,enhanced radar echoes,higher cloud tops,and more and larger precipitation *** contrast,in the stratiform cloud region,after the Silver Iodide(AgI)seeding,the radar echoes become significantly weaker at heights close to the seeding layer,with the echo tops lowered by 1.4–1.7 *** addition,a hollow structure appears at the height of 6.2–7.8 km with a depth of about 1.6 km and a diameter of about 5.5 km,and features such as icing seeding tracks *** suggest that the transformation between droplets and ice particles was accelerated by the seeding in the stratiform *** NPP and H8 satellites also show that convective activity was stronger in the convective region after seeding;while in the stratiform region,a cloud seeding track with a width of 1–3 km appears 10 km downstream of the seeding layer 15 minutes after the AgI seeding,which moves along the wind direction as width increases.

关键词： airborne Ka-band Precipitation Radar(KPR) mixed convective-stratiform clouds convective region stratiform region cloud seeding cloud microphysical properties

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THE DESIGN AND CORRECTION OF A QUANTITATIVE METHOD OF SNOW ESTIMATE BY RADAR

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Journal of Tropical Meteorology 2015年第1期21卷 92-100页

作者：蒋大凯闵锦忠才奎志 Nanjing University of Information Science & Technology Shenyang Central meteorological observatory

An optimization method is based to design a snowfall estimate method by radar for operational snow warning, and error estimation is analyzed through a case of heavy snow on March 4, 2007. Three modified schemes are developed for errors caused by temperature changes, snowflake terminal velocity, the distance from the radar and calculation methods. Due to the improvements, the correlation coefficient between the estimated snowfall and the observation is 0.66(exceeding the 99% confidence level), the average relative error is reduced to 48.74%, and the method is able to estimate weak snowfall of 0.3 mm/h and heavy snowfall above 5 mm/h. The correlation coefficient is0.82 between the estimated snowfall from the stations 50 to 100 km from the radar and the observation. The improved effect is weak when the influence of the snowflake terminal velocity is considered in those three improvement programs, which may be related to the uniform echo. The radar estimate of snow, which is classified by the distance between the sample and the radar, has the most obvious effect: it can not only increase the degree of similarity, but also reduce the overestimate and the undervaluation of the error caused by the distance between the sample and the *** improved algorithm further improves the accuracy of the estimate. The average relative errors are 31% and 27% for the heavy snowfall of 1.6 to 2.5 mm/h and above 2.6 mm/h, respectively, but the radar overestimates the snowfall under1.5 mm/h and underestimates the snowfall above 2.6 mm/h. Radar echo may not be sensitive to the intensity of snowfall, and the consistency shown by the error can be exploited to revise and improve the estimation accuracy of snow forecast in the operational work.

关键词： weather forecast radar-based snowfall estimate optimization technique correlation

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Characteristics of Spatiotemporal Distribution of Sea Surface Wind along the East Coast of Guangdong province

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Journal of meteorological Research 2018年第4期32卷 627-635页

作者： Fei LIAO Hua DENG Pak-wai CHAN Guangzhou meteorological observatory Guangzhou 511430 Guangzhou Institute of Tropical and Marine Meteorology China Meteorological AdministrationGuangzhou 510080 Guangdong Ecological Meteorology Center Guangzhou 510080 Hong Kong observatory Hong Kong 999077

We analyzed the frequency distribution characteristics of wind speeds occurring at different offshore sites within a range of 0-200 km based on the sea surface wind data captured via buoys and oil platforms located along the east coast of Guangdong province. The results of the analysis showed that average wind speed measured for each station reached a maximum in winter while minima occurred in summer, corresponding to obvious seasonal variation, and average wind speed increased with offshore distance. The prevailing wind direction at the nearshore site is the east-erly wind, and the frequency of winds within 6-10 m s^-1 is considerable with that of winds at 〉 10 m s^-1. With the in-crease of the offshore distance, the winds were less affected by the land, and the prevailing wind direction gradually became northerly winds, predominately those at 〉 10 m s^-1. For areas of shorter offshore distance （〈 100 km）, sur-face wind speeds fundamentally conformed to a two-parameter Weibull distribution, but there was a significant dif-ference between wind speed probability distributions and the Weibull distribution in areas more than 100 km off-shore. The mean wind speeds and wind speed standard deviations increased with the offshore distance, indicating that with the increase of the wind speed, the pulsation of the winds increased obviously, resulting in an increase in the ra-tio of the mean wind speed to the standard deviation of wind speed. When the ratio was large, the skewness became negative. When a relatively great degree of dispersion was noted between the observed skewness and the skewness corresponding to the theoretical Weibull curve, the wind speed probability distribution could not be adequately de-scribed by a Weibull distribution. This study provides a basis for the verification of the adaptability of Weibull distri-bution in different sea areas.

关键词： sea surface wind probability distribution observation buoy oil platform

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Typhoon Vortex Self-Organization in a Baroclinic Environment

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Acta meteorologica Sinica 2009年第5期23卷 539-549页

作者：滕代高罗哲贤余晖李春虎代刊 Zhejiang meteorological observatory Key Laboratory of meteorological Disaters NUIST Laboratory of Typhoon Forecast Technique Shanghai Typhoon Institute of CMA Shandong Provincial meteorological Bureau National meteorological Center

Self-organization of typhoon vortex in a baroclinic environment is studied based on eight numerical experiments with the fifth-generation Pennsylvania State University/National Center for Atmospheric Research （PSU/NCAR） Mesoscale Model （MM5）. The results show that, when there are only two 400-km-away mesoscale axisymmetric vortices with a radius of 500 km in the initial field, the two vortices move away from each other during co-rotating till the distance between them greater than a critical distance named co-rotating critical distance. Then, they stop co-rotating. The situation is changed when a small vortex with a radius of 80 kin is introduced in between the two vortices in the initial field, with the two initially separated vortices approaching each other during their co-rotation, and finally self-organizing into a typhoon-like vortex consisting of an inner core and spiral bands. This result supports both Zhou Xiuji＇s view in 1994 and the studies in the barotropic framework concerning the interactions between the same and different scales of vortices. Six other experiments are carried out to study the effects of the initial vortex parameters, including the initial position of the small-scale vortex, the distance and intensity of the initially axisymmetric binary mesoscale vortices. It is found that the distance between the initial axisymmetrie mesoscale vortices is the most important parameter that influences the self-organizing process of the final typhoon-like vortex. This conclusion is similar to that obtained from barotropical model experiments.

关键词： self-organization small-scale vortex mesoscale vortex typhoon vortex three-dimensional vortex

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STUDY ON THE MAIN CLIMATE MODES OF SHANDONG PRECIPITATION AND THEIR RELATIONS WITH THE EAST ASIAN WESTERLY JET

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Journal of Tropical Meteorology 2012年第1期18卷 72-80页

作者：于群吴炜周发琇王启刘彦 Laboratory of Ocean-Atmosphere Interaction and Climate(OAC) Ocean University of China Shandong meteorological Information Center Shandong meteorological observatory Shandong meteorological Service Center

Summer precipitation patterns of Shandong province are relatively independent with regard to the whole eastern China *** study the rules and causes of precipitation variations,three main climate modes-on the annual,seasonal,and climatic intra-seasonal oscillation(CISO) scales-are extracted using a harmonic analysis method based on daily precipitation of Shandong during 1965-2009 and multi-year averaged pentad precipitation at 722 stations in China during *** the three precipitation climate modes,the annual mode is closely related to the annual cycle of Earth-Atmosphere thermal system,which is characterized by the periodic dry and wet *** seasonal mode reflects the monsoon effect on precipitation and the main flood season's contribution to annual precipitation *** an important climatic signal,the CISO mode is more evident during summer *** gradual modulations of the CISO mode,seasonal mode,and annual mode control the annual variation of *** study the relationship between precipitation climate modes and atmospheric circulations,an East Asian Westerly Jet Index(EAWJI) is defined in this *** is revealed that precipitation of Shandong is closely related to EAWJI in all climate modes.A wet or dry phase of each climate mode corresponds to a specific atmospheric circulation *** phase of the annual mode is reverse to that of *** the wet phase of the seasonal mode(weak phase of EAWJI),the atmospheric circulation in and around Shandong is characterized by upper-level divergence and low-level convergence.A reversed atmospheric circulation exists for the dry phase(strong phase for EAWJI).In the summer wet phase of CISO mode(strong phase of EAWJI),Shandong is controlled by upper-level divergence and low-level ***,the dry phase is corresponding to a reversed circulation *** methodology employed in this research,*** the precipitation climatic variations in terms of indepe

关键词： precipitation of Shandong climate mode East Asian westerly jet

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Comparison of Microphysical Characteristics of Warm-sector,Frontal and Shear-line Heavy Rainfall During the Pre-summer Rainy Season in South China

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Journal of Tropical Meteorology 2023年第2期29卷 204-215页

作者：夏丰刘显通胡胜黎慧琦饶晓娜林青肖辉冯璐赖睿泽 Guangzhou Institute of Tropical and Marine Meteorology China Meteorological AdministrationGuangzhou 510641 China Guangdong meteorological observatory China Meteorological AdministrationGuangzhou 510641 China

Warm-sector heavy rainfall(WR),shear-line heavy rainfall(SR),and frontal heavy rainfall(FR)are three types of rainfall that frequently occur during the pre-summer rainy season in south *** this research,we investigated the differences in microphysical characteristics of heavy rainfall events during the period of 10-15 May 2022 based on the combined observations from 11 S-band polarimetric radars in south *** conclusions are as follows:(1)WR has the highest radar echo top height,the strongest radar echo at all altitudes,the highest lightning density,and the most active ice-phase process,which suggests that the convection is the most vigorous in the WR,moderate in the FR,and the weakest in the SR.(2)Three types of rainfall are all marine-type precipitation,the massweighted mean diameter(Dm,mm)and the intercept parameter(Nw,mm^(-1) m^(-3))of the raindrops in the WR are the largest.(3)The WR possesses the highest proportion of graupel compared with the FR and SR,and stronger updrafts and more abundant water vapor supply may lead to larger raindrops during the melting and collision-coalescence processes.(4)Over all the heights,liquid and ice water content in the WR are higher than those in the SR and FR,the ratio of ice to liquid water content in the WR is as high as 27%when ZH exceeds 50 dBZ,definitely higher than that in the SR and FR,indicating that the active ice-phase process existing in the WR is conducive to the formation of heavy rainfall.

关键词： microphysical characteristic S-band polarimetric radar warm-sector heavy rainfall frontal heavy rainfall shear-line heavy rainfall

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The Influences of Macro- and Microphysical Characteristics of Sea-Fog on Fog-Water Chemical Composition

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Advances in Atmospheric Sciences 2014年第3期31卷 624-636页

作者： YUE Yanyu NIU Shengjie ZHAO Lijuan ZHANG Yu XU Feng Collaborative Innovation Center on Forecast and Evaluation of meteorological Disasters Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological AdministrationNanjing University of Information Science & Technology Wuhan Central meteorological observatory Zhanjiang meteorological Bureau Guangdong Ocean University

ABSTRACT During a sea-fog field observation campaign on Donghai Island in the spring of 2011, fog-water, visibility, meteorological elements, and fog droplet spectra were measured. The main cations and anions in 191 fog-water samples were Na＋, NH2, H＋, NO3, C1- and SO] , and the average concentrations of cations and anions were 2630 and 2970 p-eq L 1, respectively. The concentrations of Na＋ and C1- originated from the ocean were high. The enhancement of anthropogenic pollution might have contributed to the high concentration of NH＋, H＋, and NO^-3. The average values ofpH and electrical conductivity （EC） were 3.34 and 505 uS cm-1, respectively, with a negative correlation between them. Cold fronts associated with cyclonic circulations promoted the decline of ion loadings. Air masses from coastal areas had the highest ion loadings, contrary to those from the sea. The ranges of wind speed, wind direction and temperature corresponding to the maximum total ion concentration （TIC） were 3.5-4 m s-1, 79°-90° and 21°C-22°C, respectively. In view of the low correlation coefficients, a new parameter Lr was proposed as a predictive parameter for TIC and the correlation coefficient increased to 0.74. Based on aerosol concentrations during the sea-fog cases in 2010, we confirmed that fog-water chemical composition also depended on the species and sizes of aerosol particles. When a dust storm passed through Donghai Island, the number concentration of large aerosol particles （with diameter 〉 1 p-m） increased. This caused the ratio of CaZ＋/Na＋ in fog-water to increase significantly.

关键词： ion concentration synoptic weather system meteorological element fog microphysics aerosol

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LOW-DEFORMATION VORTICITY AREAS IN SYNOPTIC-SCALE DISTURBANCES FOR TROPICAL CYCLOGENESIS：AN OBSERVATIONAL ANALYSIS

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Journal of Tropical Meteorology 2017年第2期23卷 121-132页

作者：段晶晶吴立广 Pacific Typhoon Research Center and Key Laboratory of meteorological Disaster of Ministry of Education University of Information Science and Technology Nanjing 210044 China Ningbo meteorological observatory of Zhejiang province Ningbo 315012 China State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences Beijing 100029 China

It has long been known that incipient tropical cyclones(TCs) always occur in synoptic-scale disturbances or tropical cyclogenesis precursors, and the disturbances can intensify only within a limited area during tropical cyclogenesis. An observational analysis of five tropical cyclogenesis events over the western North Pacific during 11 August to 10 September 2004 is conducted to demonstrate the role of synoptic-scale disturbances in establishing a limited area of low-deformation vorticity for tropical *** analysis of the five tropical cyclogenesis events shows that synoptic-scale tropical cyclogenesis precursors provide a region of low-deformation vorticity, which is measured with large positive values of the Okubo-Weiss(OW) *** OW concentrated areas are within the tropical cyclogenesis precursors with a radius of about 400-500 km and can be found as early as 72 hours prior to the formation of the tropical depression. When the TCs reached the tropical storm intensity, the concentrated OW is confined to an area of 200-300 radius and the storm centers are coincident with the centers of the maximum OW. This study indicates that the tropical cyclogenesis occurs in the low-deformation 18-72 hours prior to the formation of tropical depressions, suggesting the importance of low-deformation vorticity in pre-existent synoptic-scale disturbances. Although the Rossby radius of deformation is reduced in TC genesis precedes,the reduction does not sufficiently make effective conversion of convective heating into kinetic energy within the low-deformation area. Further analysis indicates that the initial development of four of the five disturbances is coupled with the counterclockwise circulation of the mixed Rossby-Gravity(MRG) wave.

关键词： synoptic-scale disturbances low-deformation vorticity Okubo-Weiss parameter Rossby radius of deformation

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Precipitation seesaw phenomenon and its formation mechanism in the eastern and western parts of Northwest China during the flood season

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Science China Earth Sciences 2019年第12期62卷 2083-2098页

作者： Qiang ZHANG Jingjing LIN Weicheng LIU Lanying HAN Institute of Arid Meteorology China Meteorological AdministrationKey Laboratory of Arid Climatic Change and Reducing Disaster of Gansu ProvinceKey Open Laboratory of Arid Climatic Change and Disaster Reduction of CMALanzhou 730020China Gansu Provincial meteorological Bureau Lanzhou 730020China Lanzhou Regional Climate Center Lanzhou 730020China Lanzhou Central meteorological observatory Lanzhou 730020China

Extending across three major plateaus,namely the Qinghai-Tibetan Plateau,the Inner Mongolia-Xinjiang Plateau and the Loess Plateau,Northwest China has the complex terrain and spatio-temporal climate variations,and is affected by the interactions among different circulation systems,such as the summer monsoon,the westerlies and the plateau *** understanding of the climate variability,as well as its characteristics and evolution mechanisms in this area has been limited so *** this paper,the precipitation characteristics and mechanisms in the eastern and western parts of Northwest China during the flood season are compared and analyzed based on the data from 192 national meteorological observational sites in Northwest China in *** results show that,divided by the northern boundary of the East Asian summer monsoon,there are huge differences in the precipitation variation characteristics between the eastern and western *** inter-annual variations,interdecadal variations and total trends in the two parts all show a significant seesaw ***,it is found that the seesaw phenomenon of precipitation variation is closely related to the opposite variation between the East Asian summer monsoon index(MI)and the westerly circulation index(WI).In addition,the inverse variations on different time scales are only related to the contributions of precipitation at specific ***,in the two matching patterns of precipitation in the seesaw phenomenon,the middle and high latitudes are occupied by the"high-low-high"wave trains in the precipitation increases in the east of Northwest China(ENWC)and decreases in the west of Northwest China(WNWC)pattern,meaning precipitation increases in ENWC and decreases in *** the opposite"low-high-low"wave trains at 500 hPa height are observed in the middle and high latitudes in the WH-EA pattern at 500 hPa height,meaning precipitation increases in WNWC and decreases in ***,the atmosphere circul

关键词： Northwest China Precipitation changes Seesaw phenomenon Summer monsoon system Westerly circulation system South Asian High

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