利用多源气象数据资料,对2018年8月17-20日台风"温比亚"引发山东历史极端暴雨的环境场进行研究.结果表明:(1)台风"温比亚"影响山东,引起的前期强降水位于鲁南地区,主要为台风外围螺旋云系降水,19日白天至夜间是此次强降水主要时段,主要受台风和西风槽相互作用引起,落区主要集中于台风倒槽附近.(2)副高稳定少动、中低纬系统相互作用及低空急流的稳定维持是此次台风强降水的主要原因.(3)超低空急流相比低空急流对出现强降水更具指示意义,强度大小影响降水的强弱程度,且超低空(500 m以下)出现20 m·s-1以上的强风速对短时强降水有明显指示作用.低空急流指数对强降水特别是中小尺度强降水及雨强大小有一定预示作用.(4)特殊地形在此次台风暴雨中有较大作用,地形的迎风坡效应在山地产生的强迫抬升作用及山脉阻挡引起的水汽在山前积聚等动力和热力共同作用触发湿对流是此次台风出现短时强降水的重要触发机制.(5)此次台风暴雨过程Q矢量散度负值的强弱对于未来6 h雨强大小有较好的指示意义.另外,此次台风特大暴雨与冷空气密切相关.

利用常规气象资料、NCEP FNL 1°×1°再分析、风廓线雷达、云顶亮温(black-body temperature,TBB)及逐时自动气象站降雨量资料,对2019年8月10—13日由台风"利奇马"引起山东极端暴雨的多尺度特征进行分析.结果表明:(1)此次台风特大暴雨主要为中低纬系统相互作用及台风倒槽本体直接影响产生,其与冷空气密切相关.冷暖空气交汇有利于山东大部地区稳定性降水长时间持续发生.冷空气从低层侵入暖湿气流底部,形成冷垫,使得暖湿气流在冷垫上滑行,加大降水强度.(2)低空急流指数的变化提前1 h预示了降水的出现及未来小时雨量的增减,其峰值出现预示着未来3h的强降雨时段,即对强降雨时段的出现和雨强大小有一定的预示性,低空急流向低空的快速扩展对应着短时强降水的开始.可以用于强降水的短时临近预报.(3)Q矢量散度负值的强弱对于未来6 h的雨强大小有较好的指示意义.(4)淄博西河镇出现全省最大降雨量与其朝向东北的喇叭口地形和对流层低层东北风倒灌有关.(5)TBB场能较直观地反映强降水过程中降水的分布和强度.风廓线雷达超低空风场的变化对雨强大小和出现最大雨强的时段有着明显的指示意义.

利用3部风廓线雷达资料对2016年2月12—13日鲁中地区出现的一次雨雪天气过程进行分析.结果表明:(1)此次雨雪天气是由低涡和地面气旋共同作用造成的一次回流降水过程,强降水出现在气旋中心的北侧冷区中,925 hPa和近地面气温下降到0℃以下是雨转雪的重要标志.(2)1 km以下超低空风场变化是降水开始的信号,低层冷垫强度的变化决定降水相态的转变,降雪时雷达最大探测高度比降雨时有明显下降;低空切变指数在降水开始和结束时会出现较大幅度增大,降雨持续阶段低空切变指数的小幅增加与雨强增强相对应.(3)风廓线雷达垂直速度不仅能体现降水强度的变化,同时也能反映降水相态的变化,降雨转雨夹雪转降雪过程中近地面的垂直速度逐渐变小.(4)大气折射率结构常数和信噪比随高度均呈现逐渐减小趋势,两者的变化能够反映降水强度的变化,均具有零度层亮带特征,亮带的消失对应降雪的开始.

利用鲁中地区2001-2016年伴随瞬时风力不低于8级的所有强对流天气个例共106次进行分析,总结其气候特征,并通过箱须图的形式研究了分类强对流天气相关环境参数的分布特征和预报阈值.结果 表明:2001-2016年强对流天气分布呈山区多、平原少、中部多、北部和西南部少的特点;6月和6月中旬是主要月份和旬份;地面辐合线是最主要触发机制类型;雷暴大风型、冰雹雷暴大风型和强降水混合型对应的地面和850 hPa的平均温度露点差,0～1 km和0～3 km垂直风切变,SWEAT指数、LI指数、K指数、风暴相对螺旋度、高度指数等环境参数各有不同的最低阈值;鲁中地区易发生强对流天气的0℃层高度为4.1 km左右;对于伴随冰雹的强对流天气,其融化层高度比0℃层高度低0.6km左右.根据以上环境参数的分布特征、高低空垂直风切变的强弱变化可对3类强对流天气进行一定程度的区分.

利用常规气象观测资料、NCEP/NCAR再分析资料和多普勒天气雷达资料,对2016年8月6—8日潍坊一次强对流天气的成因和预报误差进行了分析,结果表明:1)500 hPa冷涡底部低槽、850 hPa低涡切变线和地面倒槽是主要影响天气系统,数值预报对此次天气过程的影响系统预报偏差大,而预报员对数值预报依赖程度高是此次预报失误的主要原因;2)850 hPa以下强的水汽辐合是强降水发生的重要条件,低层辐合和高层辐散配置导致的强垂直上升运动是暴雨产生的动力机制,位势不稳定因中高层的冷空气入侵下沉得以加强;3)列车效应和强回波维持少动是造成短时强降水的重要回波特征,逆风区的发展和移动对于判断强降水的落区有指示作用,多普勒雷达反演风场中的中尺度辐合线是导致局地强降水发生的直接原因;4)风廓线雷达水平风场可以连续地反映降水过程中风场垂直结构及其变化,降水发生前探测高度明显升高,中高层冷空气侵入时间与强降水的时段相对应.

In this paper,106 strong convective cases accompanied with instantaneous winds at or exceeding the scale 8 in the central region of Shandong Province in 16 years are classified into three types:Thunderstorm,hail thunderstorm and mixed type of heavy rainfall.Using conventional sounding data and ground observation data,distributions of several key environmental parameters and thresholds corresponding to the three types are discussed respectively by the form of box and whisker plots.Furthermore,significantly severe convection cases among the 106 cases,including significant thunderstorm and strong wind cases with instantaneous wind speed exceeding 25 m/s,significant hail cases with the diameter of hails equal to or larger than 20 mm,and significant short-term heavy rainfall cases with the intensity about 50 mm/h or above,are extracted to form a subset.Distributions and forecast thresholds for significantly severe convection cases mentioned above are discussed and compared with the corresponding key environmental parameters for the total cases.Finally,the triggering mechanism for the strong convective system is briefly described and discussed.Results suggest that the minimum threshold of temperature difference between 850 and 500 hPa is 25℃ for the development of thunderstorms,hail thunderstorms and mixed type of heavy rainfall,while their corresponding minimum thresholds of ground dew point temperature are 13,16 and 24℃,the atmospheric precipitation thresholds are 20,24 and 32 mm,the thresholds of CAPE are 300,900 and 1300 J/kg,thresholds of 0-6 km wind vector difference are 12,12.5 and 8 m/s,respectively.The distributions of ground dew point temperature,atmospheric precipitation and warm cloud thickness can be used to distinguish the above mentioned three types of strong convective weather,but it is difficult to distinguish thunderstorms and hail thunderstorms through the distributions of these key parameters.For the strong convective weather associated with hail,the appropriate melting layer height is 3.0-3.9 km.Compared with the three types of all strong convection cases,the conditional instability for significant thunderstorms,significant hail thunderstorms and significant mixed type of heavy rainfall significantly increases,which is reflected in the fact that the temperature difference between 850 and 500 hPa,the water vapor condition,and the CAPE all increase.Corresponding to the above mentioned three types,the minimum thresholds of CAPE are 1000,1100 and 2000 J/kg,and the 0-6 km wind vector shears are 16,12 and 11 m/s,respectively.The thresholds of vertical wind shear for significant thunderstorms and significant mixed type of heavy rainfall increase obviously.The above work forms a basis for the short-term forecast of strong convective weather.Combined with the climatological occurrence probability,a short-term forecasting system for classified strong convective weather can be established for regional meteorological stations by means of decision tree or fuzzy logic method.

利用常规观测资料、地面加密自动站资料、多普勒天气雷达资料以及NCEP/NCAR再分析资料,对2016年6月14日山东一次强对流天气的环境条件、风暴特征进行了分析.结果表明:(1)6月14日强对流天气主要发生在横槽转竖引导冷空气南下和低层暖湿气流交汇的环流形势下,地面辐合线是抬升机制.上千下湿的不稳定层结、低层水汽充沛及湿层厚是出现短时强降水的重要原因.假相当位温差(△θse)和风暴相对螺旋度(SRH)对强对流天气有较好的指示意义;(2)较低的融化层高度、适宜的0℃层和-20℃层高度是大冰雹的发生指标.抬升凝结高度低、PWV较大等对短时强降水具有指示作用;(3)垂直风切变较大,风暴承载层平均风远大于风暴移动速度,致使超级单体持续时间长,并具有高悬强回波、有界弱回波区、回波悬垂、风暴顶辐散、倒“V”型缺口、中层径向辐合、中气旋、“钩”状回波和三体散射等回波特征;(4)降雹发生在Zmax大值期、VIL和DvIi最大时段、HGT增高期.中气旋厚度、最大切变和持续时间与天气的强烈程度密切相关.

利用常规观测、区域自动气象站、NCEP/NCAR再分析和雷达回波资料,对2016年6月30日山东一次阵风锋触发的强对流天气进行了分析.结果表明,此次强对流主要发生在高空槽与副热带高压相互作用、山东高低层受一致西南气流影响的环流形势下,阵风锋、地面辐合线和负变压中心所产生的抬升作用及近地面层冷空气的侵入使气温骤降是触发对流的关键因素.低层水汽充沛、湿层厚,属于上干下湿的不稳定层结.强对流发生区域处在假相当位温差(Δθse)和风暴相对螺旋度(storm relative helicity,SRH)的大值中心及其右侧位置.对流有效位能(convective available potential energy,CAPE)、850 hPa与500 hPa之间温差、大风指数、强天气威胁指数等都对此次强对流有较好的指示作用.0℃层高度和融化层高度较高是此次过程未出现大冰雹的原因.较强的0～3 km垂直风切变在强对流预报业务中需要注意.此次强对流过程是线状回波带前侧风暴内出现了阵风锋,阵风锋又不断触发雷暴使个别强单体风暴发展加强成为超级单体风暴,具有持续时间较短的中气旋、高悬的强回波、有界弱回波区、风暴顶辐散、窄带回波、径向速度大值区等回波特征.风暴移动速度比风暴承载层平均风速大,缩短了超级单体存在时间.此外,风暴参数与天气的强烈程度密切相关.

Using surface and high conventional observations,radar echo data and automatic weather station data of Yantai and Qingdao,two strong convections triggered by sea-breeze front in Shandong Peninsula on 14 July 2014 and 29 June 2009 are analyzed.The convection on 14 July 2014 occurs under circulation patterns of forward-tilting trough in the back of cold vortex,where dry and cold air at middle and upper layer is strong,warm and humid air at low layer is weak,leading to obvious static instability stratification and moderate convective available potential energy.The vertical wind shear is from weak to moderate,therefore the duration of supercell is short,and the range of hail is small.The convection on 29 June 2009 appears under circulation patterns of a typical northeast cold vortex,and strong vertical wind shear is a principal factor in the maintenance of supercell.Sea-breeze front,gust front and convergence line of surface are triggering systems.The high convective available potential energy,temperature and pseudo equivalent potential temperature difference between 850 hPa and 500 hPa,average wind speed of storm bearing layer,wind indices,and potential downside indices are indicative to the intensity of convection.Both processes have supercell storms,showing similar echo characteristics,such as hanging strong echoes,weak echoes regions,echo pendency,hook echoes and mesocyclones.The difference is that there is a strong mesocyclone on 29 June 2009,while the mesocyclone on 14 July 2014 is much weaker,so the former has a larger convection range and stronger intensity.The collision process between sea breeze front and gust front enhances the mesocyclone,and when one factor weakens the mesocyclone weakens too.Two hail processes appear in the decline phase of cell top and echo top,maximum period of a storm with maximum reflectivity.The strong radar echoes over 50 dBZ in both processes extend to much higher than the height of -20℃.Lower melting level,suitable height of 0℃,thick depth of negative temperature layer are important to large hails.In addition,the formation period of large hails are in the period of low base height,deep thickness,severe rotation intensity of mesocyclone and is simultaneous with the strong period of mesocyclone.Therefore,the size of hail is related to base height,thickness,and rotation intensity of mesocyclone.Supercell storms of two processes occur to storms of the sea-breeze front which is close to the mountains.The stronger uplift triggering caused by combination of terrain and sea-breeze front is critical to strengthen original convective storms and evolve into supercell storms.

利用常规地面和高空观测资料、加密自动站资料和多普勒雷达资料,对2016年6月山东两次强对流天气的雷达特征、环境条件等进行了对比分析,结果表明:6月14日强对流天气主要是横槽转竖引导冷空气南下引起,6月30日强对流天气发生在高空槽前、山东高低层受一致西南气流影响的环流形势下,地面辐合线是两次过程的触发机制.6月14日垂直风切变和风暴承载层平均风均比30日大很多,致使14日的超级单体风暴持续时间更长、强度更强.风暴相对螺旋度的大小对强对流天气强弱程度有指示意义.两次过程都在地面辐合线附近生成,都具有中气旋、高悬的强回波、有界弱回波区、回波悬垂、风暴顶辐散等雷达特征,不同的是14日具有倒V形缺口、中层径向辐合、冰雹散射和钩状回波等特征,30日具有窄带回波、径向速度大值区等特征.两次过程都出现了弱旋转对应地面都带来小冰雹天气,这在预报业务中值得注意.两次降雹与风暴单体高度及强度、垂直累积液态水含量及密度、中气旋厚度、最大切变和持续时间密切相关.

Using the data of climatic resources of precipitation in nine counties (cities and districts) in Weifang City from 1961 to 2016,the change characteristics of precipitation in Weifang City in recent 56 years were analyzed by linear trend statistical analysis method.The results showed that the precipitation of Weifang City in the past 56 years mainly concentrated in summer,and the proportion of precipitation in spring and winter accounted for a very small proportion in the whole year.Precipitation decreased overall with a rate of 24.05 mm/10 a,and the interdecadal variation was significant.Precipitation in the 1960s and 1970s was at a high level,and precipitation in the 1980s and 1990s was obviously less.

Using daily precipitation data,conventional data,sea surface temperature data,and NCEP/ NCAR reanalysis data from 2000 to 2013,the characteristics and causality of cold airflow snowfall in the Laizhou Bay are analyzed.The results show that the snowfall intensity is small,and the moderate and heavy snow are mainly concentrated in the eastern region of the Laizhou Bay.Duration of snowfall is short within 12 hours.Cold-airflow snowfall happens more frequently in the east and less in the west of the Laizhou Bay and their inter-annual variation are obvious.Marked periodic variation of 6 to 7 years is found.Cold-airflow snowfall often occurs in January,especially from the last ten-day of December to the first ten-day of January and mainly around 08:00 in the morning.There is a positive correlation between the annual cold air activity index and the number of cold airflow snowfall events.There are obvious temperature thresholds at ＜ 850 hPa levels during cold-airflow snowfall events.Cold-airflow snowfall happens less at too high or too low sea surface temperature and air-sea temperature difference over the Laizhou Bay,and the ground temperature threshold (at 2 m) is below 5 ℃,which is higher than the inland snowfall threshold.Cold-airflow snowfall often happens in the northwest airflow behind a trough (including behind eddy) at 500 hPa and the northwest winds at 700 hPa and 850 hPa,and there exist three circumfluence situations:northwest,north,and northeast winds at 925 hPa and 1000 hPa.

利用1952-2012年潍坊地区9个气象站的冰雹观测资料和冰雹气象灾害资料,对潍坊地区冰雹的时空变化特征进行统计分析.结果表明:1952-2012年潍坊地区大冰雹出现较多,降雹持续时间大于20min以上的冰雹所占比例最大,灾害相对较重.潍坊发生冰雹天气的局地性较强,地形及地理位置对潍坊地区的局地降雹起很重要的作用.冰雹日数的地理分布与地形相关,呈山区多、平原少的特点.6月是潍坊地区降雹的主要月份,其中6月中旬冰雹出现频率最高.冰雹日数的月变化呈先增后减的趋势.午后14-16时潍坊市降雹概率最大.潍坊市冰雹日教具有明显的年代际变化,并存在显著的16 a和2a左右的周期变化.1970年是冰雹日数的气候突变年份,自1970年后冰雹发生频率呈上升的趋势,特别是1974年后尤其显著.潍坊地区冰雹日数与同年份的冷空气活动指数呈显著的负相关,说明冷空气活动指数对潍坊地区的冰雹日数影响较大.

利用高空观测资料、地面观测资料、加密自动站资料、NCEP/NCAR全球再分析资料、FY-2E卫星云图等资料对2012年第10号台风“达维”影响山东的暴雨落区分布及路径特征进行了分析.结果表明:暴雨落区主要出现在台风移动路径的右侧及台风中心附近,而且台风中心的右侧降水明显大于左侧.冷空气对台风引起的降水落区影响较大.水汽通量大值区和辐合区分布、中层的强上升运动对暴雨落区有一定作用.温度梯度大值区和假相当位温的分布与暴雨落区较一致.台风“达维”是在300 hPa引导气流的作用下移动的,其移动路径与500hPa总温度线的走向及高空500hPa正涡度带的走向一致.此外,台风的移动路径与副热带高压、双台风效应、低层弱冷空气和下垫面等关系较大.

利用常规观测资料、地面加密区域自动站观测资料、NCEP/NCAR资料、FY-2E卫星云图等资料对2012年7月4-5日潍坊地区出现的首场局地大暴雨天气过程进行了分析.分析表明:此次局地大暴雨的主要影响系统为高空低槽、低涡切变线、低空急流和气旋.局地大暴雨区域与水汽通量大值区和辐合中心比较对应.超低空急流出现的时间和位置对降水强度的增加和出现的区域具有重要作用.地面中小尺度辐合中心的持续时间对此次局地大暴雨的贡献较大.临朐区域站出现大暴雨与特殊地形有关.此次暴雨是出现在等θe线陡立密集区内、对流层低层MPV1＜0的对流不稳定条件下且MPV2绝对值得到较大增长的区域.中尺度对流云团范围和强度的不断变化对判断暴雨的发生发展有重要的指示意义.

为了避免冰雹灾害给社会造成不必要的损失,达到防灾减灾的目的,更好地做好冰雹天气预报,利用常规观测资料、雷达和FY-2E卫星TBB资料,对2012年6月初潍坊市出现的一次典型冰雹天气过程进行了成因分析.结果表明:此次冰雹天气过程发生在东北冷涡和前倾槽的环流背景下,强烈的上升运动为此次天气提供了动力条件,地面中小尺度辐合线是此次冰雹天气的触发机制.适宜的0℃层和-20℃层高度及大的环境风垂直切变有利于雹粒的增长.另外,此次天气发生在对流云团发展最旺盛的时段,位置位于大于232 K的冷云盖移动方向的前端到等温线梯度大值区附近,这对冰雹天气落区的预报有较好的指示意义.

In order to strengthen the understanding of the causes of the rainy weather,so as to improve the forecast accurate rate of this kind weather,thereby reducing the economic loss caused,the author analyzed the continuous autumn rain process in September 11-19,Shandong by using NCEP,satellite cloud pictures and MICAPS conventional observation data and so on.The results showed that:the autumn rainy periods lasted for a long time,range,high strength;the circulation background happened autumn rainy periods of subtropical high withdraw south late and north by position,ridge line in 30° N near;the reason of process was the subtropical high of west southwest air and cold air phytoseiid interchanged in Shandong;during the autumn rainy periods,and large circulation over relatively stable,high pressure forces blocked the ural strong and stable,and there was a Lengguo near Lake Baikal,at the same time,the subtropical high and the south Asia high pressure and subtropical west breeze rushing abnormal partial strong,north and stable maintain the autumn rainy periods for providing favorable conditions of large scale circulation background;during the rainfall,northeast to southwest toward cloud belt had remained above in Shandong Province,and the band ' s northern and 700 hPa shear line ' s position was consistent.

Based on conventional observation data, the surface observation of automatic weather station, wind profile data from Doppler ra-dar, satellite images and NCEP 1°×1° reanalysis data, the contrast analysis for two successive torrential rain processes occurred in Shandong province on 8 July and 10 July 2012 is made. The results indicate that the former process occurs against the circulation background of the subtropical high pressure continuously strengthened and unstable energy increased, and the later process takes place against the circulation background of the subtropical high pressure weakened and withdraw towards south as well as unstable energy released. The common large scale environmental conditions of the two processes include that the vertical motion and the low-level jet developed intensely over the torren-tial rain area and it has divergence at the upper-level, convergence at the middle and lower level. There are differences between the two pro-cesses. In the former process, intensity and distribution of severe precipitation is consistent with strong vertical upward movement, strong con-vergence in the low-level, strong divergence in the upper-level and water vapor flux convergence center. But in the latter process, the consis-tence mentioned above is poorer than that in the former one. Strong development of southwest jet is corresponding to the periods of severe pre-cipitation in the two processes. Development height of southwest jet is lower, the wind is much stronger, and when severe precipitation ended the downward dissemination speed of cold air is faster and the height of cold air is lower in the latter process than that in the former one. It has a certain prediction significance for severe precipitation nowcast that with lower cloud top temperature, higher development level of convec-tion system, longer continuance of cloud top temperature center below-70℃, severe precipitation emergences in the low value center and in the great gradient zone of cloud top temperature in the latter process.

利用高空、地面实况观测和MICAPS再分析资料，对2007年8号台风蝴蝶和2008年7号台风海鸥影响山东的两次暴雨过程进行了诊断分析，其中主要从环流背景、海平面气压场、水汽输送和流场、湿位涡四个方面对两次降水过程进行对比分析。结果表明：两次台风影响山东的共同特点为在降水初始阶段台风低压倒槽或外围环流与冷空气结合产生远距离对流性暴雨；两次过程不同之处在于2007年8号台风蝴蝶的低压倒槽北上过程中在地面低压倒槽北侧形成明显的正MPV1柱，且该地区上空正MPV2明显加强，导致温带气旋发展，2008年7号台风海鸥北上过程中没有形成正MPV1柱，没有明显的正MPV2区域，故低压环流没有继续加强。这对今后预报台风暴雨落区具有重要的指示意义。

利用潍坊市气象局1961～2011年气温观测资料,分析了近51年来潍坊市冬季数九期间的气温变化情况。结果表明:近51年来潍坊市数九期间气温整体呈上升趋势,极端最低气温、平均最低气温增幅大于平均最低气温、平均最高气温增幅,导致日较差减小;平均气温为～1.35℃,平均每年上升0.047℃,67、68年气温异常偏低,01、06年气温异常偏高;潍坊市数九期间最冷的时间段80年代以前是5九,后期是4九。