一次强冷空气影响广东海面8级强风的物理成因

对强冷空气影响下的一次广东省海面8级强风物理过程进行了分析,结果表明：低层冷平流的增强,使地面正变压场及变压梯度增强,是导致这次海面强风过程的重要原因。     

粤东海面冷空气强风的统计分析与预报

近年粤东海面强风日数比过去偏少,分析粤东海区不同季节强风天气形势,气压差与海面风的相关性表明,随着时间后延,相关系数极大值从东南沿海向西北方向延伸,6、12、24、48 h相关性最好地区分别位于福建沿海、浙江沿海、长江中下游、河套地区.确定强风预报指标,用统计方法建立了强风的回归预报方程.     

一次寒潮强风天气过程分析

１９９５年１１月７日出现的寒潮强风天气过程是由于冷空气不断堆积产生强的气压梯度风,地面迅速加压产生强变压风,冷高压脊前高空动量下传产生强的动量下传风所谓三风合一的所造成。影响范围之广,持续时间之长均为历史上所罕见。     

广东一次补充型冷空气过程分析

本文通过对2001年1月的一次强冷空气过程分析，总结出在500hPa南槽北脊高低纬反位相配置形势下，不利于冷空气南下越时南岭，低层冷空气只能在南岭北侧堆积，但当冷空气堆积到南岭两侧温差超过10℃以上，南岭以北的冷空气积聚已达临界值，一次不太强的冷空气补充也会使冷空气冲破南岭屏障，这时影响广东的冷空气已经是前几次叠加，强度明显加强。     

完全预报（PP）方法在广东冬半年海面强风业务预报中的应用

在进行大量普查分析和统计的基础上, 将最近10年历史天气图的地面气压和有关海面强风代表站的风场资料在日本数值预报模式输出报文的1.25°×1.25°格点分布上进行客观分析, 对比传统的以关键区域划分冷空气入侵路径与广东海面强风的关系, 提出了一套与广东冬季海面强风关系更密切、作用更直接的地面关键区气压场分布特征进行客观定量的分型;根据梯度风原理, 用经验加统计的因子挑选方法, 形成了一套应用日本数值预报模式输出、适用于广东海面强风预报的完全预报(PP)方法。检验和业务试用结果均表明:该方法对广东的海面强风具有较强的预报能力;用完全预报方法做沿海海面强风预报是可行的。     

环渤海区域强风过程的气候特征模拟分析

采用欧洲中期天气预报中心ERA-interim再分析资料驱动WRF模式,对环渤海区域1981—2012年123次强风过程进行了模拟,并对不同天气系统形势下环渤海区域强风过程的气候特征进行了分析,得到以下结论：1）WRF数值模式可以较好地模拟环渤海区域强风过程的发展演变特征。2）西北路冷锋过程引起的环渤海区域强风强度较其他过程偏强,强风集中在辽东半岛西部、渤海海峡和山东半岛东部。黄河气旋引起的强风过程与冷锋相比,分布特征有着明显的不同,强风主要集中在山东半岛东部及黄海海域,渤海海域的强风相对偏弱。3）强风过程存在明显的季节变化,秋冬季强风持续时间长,风速大,春季次之,夏季最弱。4）强风过程在渤海海域的最大风速呈增加趋势,而在渤海海峡以东海域和山东半岛南部呈减小趋势。     

北京地区一次特大强风过程边界层结构的研究

利用北京325 m气象塔资料对1993年4月9日北京地区出现的一次特大强风过程的边界层结构（风、温、风切变及阵风特征）进行了分析。随着该次大风的过境，边界层内风场出现数个风速高值中心，高度位于200～300 m，时间间隔1～3 h。伴随上层风速垂直切变和阵风特性。湍流能谱的计算结果表明了大尺度涡旋对边界层湍流微结构的影响。     

基于测风塔实测台风威马逊登陆过程的强风特性分析

利用广东省徐闻县西连镇90 m测风塔在1409号超强台风威马逊登陆期间获取的具备完整的台风代表性的观测数据以及处于台风外围的广东省茂名市博贺镇100 m测风塔的观测数据,对台风威马逊的近地层强风特性进行了分析,西连测风塔结果表明:风速时程曲线呈明显的"M"型分布特征,台风中心经过测风塔前后,风向沿逆时针方向大幅偏转约170°。风速随高度增加而增大,风速廓线较好地符合对数和幂指数律;台风过境前后,各强风区的风速廓线幂指数和粗糙长度呈先减小后增大的特点;粗糙陆地下垫面的风速廓线幂指数和粗糙长度较大。湍流强度和阵风系数在前外围强风区或后外围强风区较大,在前眼壁强风区或后眼壁强风区较小,湍流强度和阵风系数随高度增加而减小,基本符合指数为负值的幂指数律;粗糙下垫面对湍流强度和阵风系数有增大的作用。外围强风区和眼壁强风区的10 min风向变率变化较为平稳,而在眼区变动较为剧烈,在眼区,当风速达到最低值或次低值时,10 min风向变率幅值达到最大值。博贺测风塔结果表明其总体上与西连测风塔台风前外围和前眼壁强风区的情形相似。     

广东一次强对流天气过程分析

利用常规探测资料和雷达等非常规资料,对2007年4月17日一次大范围强对流过程的天气背景、物理量诊断、雷达回波演变特征等进行了分析,结果表明:雷达反射率图上出现的三体散射回波以及对应的径向速度图上中等强度的中气旋预示着强冰雹的出现,局地剧烈天气(大冰雹和11级强风)出现在锋前,而大范围的强对流天气则出现在锋面附近;干冷...     

一次暴雪过程前后近地层物理量场特征分析

利用铁塔风梯度观测资料和超声风温仪观测资料,对2008年1月18—21日暴雪前后,湖北黄石长江岸边近地层风场和湍流作了计算分析,探索其异常变化特征,为认识黄石地区暴雪近地层发生发展的物理过程提供依据。结果表明,暴雪前,风向转变,水平风速和垂直风速明显增大,湍流通量的输送较活跃,湍流动能和湍流强度有显著峰值出现;降雪过程结束后,湍流动能再次增大后缓慢减弱。可见此次暴雪过程前后近地层物理量场有异常变化     

近40多年广东省的寒潮活动

利用广东省１１个代表站１９５１－１９９４年每日气温（包括日平均和日最低气温）资料,分析了广东省近４４年来寒潮活动的气候特征。首先,根据广东省气象局规定的寒潮标准,寻找出每个站所有的寒潮过程,在引基础上分析了广东寒潮的地区分布特征。其次,只要１１个代表站中１站或１站以上出现寒潮就认为是一次寒潮过程。在此条件下的统计表明,广东省在４４年中一共出现了１０３次寒潮过程,影响时间从１０月底至３月中旬,其中以     

一种台风海面非对称风场的构造方法

针对台风数值预报中由于采用对称模型而导致预报误差的现实，通过引入非对称分布的台风最大风速、最大风速半径等因子，在得到台风报告中7级风和10级风的半径的基础上，利用最佳权系数方案来得到非对称的台风外围风速分布因子，从而对Chan and Williams 1987年提出的切向风廓线方案进行改造，进而得到了台风海面非对称风场的计算式。检验表明，该方法能够描述台风海面风场的非对称分布，具有较好的应用前景。     

1949—2009年欧亚大陆强冷空气活动频次的变化特征

利用NCEP/NCAR提供的1949—2009年sig995层逐日平均温度资料,分析了近60 a欧亚大陆强冷空气活动频次年际变化的地区差异,并讨论了强冷空气活动的区域特征以及各区域强冷空气活动的变化特征。结果表明:欧亚大陆强冷空气活动可分为34个变化区,按照年代际变化及地理位置相邻可进一步归纳为9类地区。9类地区的强冷空气活动年频次存在共同变化特征,例如在20世纪60年代末至80年代中期普遍偏少;但也存在差异,例如80年代中期至90年代初高纬度地区偏多,而较低纬度的中国以及周边地区偏少。值得注意的是,新地岛周边地区以及西伯利亚中、南部地区强冷空气活动频次始于20世纪90年代中期的下降趋势延续至今,近几年欧亚大陆多数地区强冷空气活动频次偏少。     

THE TEMPORAL AND SPATIAL DISTRIBUTION OF SEA SURFACE WIND ALONG THE COAST OF GUANGDONG PROVINCE IN CHINA

Temporal and spatial distribution characteristics of sea surface wind in Guangdong''s coastal areas were analyzed with data from four offshore observational stations between 2012 and 2015. The results are shown as follows: (1) The probability distribution of wind speed was basically consistent with Gaussian distribution characteristics; winds of Beaufort force 6 or higher were observed mainly in far offshore stations from October to March. (2) The probability distribution of wind direction was represented well by Weibull distribution. The deviation of wind direction of far station was relatively small for it was mainly controlled by monsoon over the South China Sea, while the near offshore station had a relatively large diurnal variation because of the influence of local synoptic systems such as sea-land breeze. (3) There were significant seasonal differences in wind speed and direction observed by different offshore observational stations. In strong wind seasons, the deviation of wind direction was relatively small while the deviation of wind speed was relatively large, and vice versa. In contrast with Class I station, the other three stations exhibited approximately normal distribution of wind direction and wind speed deviations. (4) Wind direction diurnal variation was moderate in windy periods, while it was obvious in relatively lower speed conditions. The deviation of wind speed in windy periods was generally greater because it was influenced by mesoscale weather systems for 10-20 h, and the influence was complicated, resulting in greater local differences in wind speed.     

NIM陆面过程模式的研究Ⅱ：青藏高原夏季陆面过程的数值模拟

采用南京气象学院（NIM）5层陆面过程模式，利用1979年5－8月“青藏高原气象科学实验”资料模拟和分析了夏季青藏高原不同地区的陆面特征和地表能量特征。并将模拟值与根据观测资料计算得到的感热和潜热以及观测得到的净辐射、土壤温度、土壤热通量进行了对比。结果表明，NIM5层陆面过程模式可以模拟青藏高原夏季不同下垫面情形下的能量交换过程。     

UNCERTAINTY IN THE SPECIFICATION OF SURFACE CHARACTERISTICS: A STUDY OF PREDICTION ERRORS IN THE BOUNDARY LAYER

The effects of uncertainty in the specification of surface characteristics on simulated atmospheric boundary layer (ABL) processes and structure were investigated using a one-dimensional soil-vegetation-boundary layer model. Observational data from the First International Satellite Land Surface Climatology Project Field Experiment were selected to quantify prediction errors in simulated boundary-layer parameters. Several numerical 12-hour simulations were performed to simulate the convective boundary-layer structure, starting at 0700 LT 6 June 1987.In the control simulation, measured surface parameters and atmospheric data were used to simulate observed boundary-layer processes. In the remaining simulations, five surface parameters – soil texture, initial soil moisture, minimum stomatal resistance, leaf area index, and vegetation cover – were varied systematically to study how uncertainty in the specification of these surface parameters affects simulated boundary-layer processes.The simulated uncertainty in the specification of these five surface parameters resulted in a wide range of errors in the prediction of turbulent fluxes, mean thermodynamic structure, and the depth of the ABL. Under certain conditions uncertainty in the specifications of soil texture and minimum stomatal resistance had the greatest influence on the boundary-layer structure. A lesser but still moderately strong effect on the simulated ABL resulted from (1) a small decrease (4%) in the observed initial soil moisture (although a large increase [40%] had only a marginal effect), and (2) a large reduction (66%) in the observed vegetation cover. High uncertainty in the specification of leaf area index had only a marginal impact on the simulated ABL. It was also found that the variations in these five surface parameters had a negligible effect on the simulated horizontal wind fields. On the other hand, these variations had a significant effect on the vertical distribution of turbulent heat fluxes, and on the predicted maximum boundary-layer depth, which varied from about 1400–2300 m across the 11 simulations. Thus, uncertainties in the specification of surface parameters can significantly affect the simulated boundary-layer structure in terms of meteorological and air quality model predictions.     

BASIC CHARACTERISTICS OF SURFACE WIND. PRESSURE AND TEMPERATURE IN PLATEAU OF MONGOLIA

After analyzing the mean pressure, dominant wind and temperature data of 40 observation sta-tions in Mongolia from 1961 to 1990, we reach some conclusions as below: (a) The warm advec-tion in the free atmosphere hardly reaches the ground in the west in winter. Because of thermody-namic differences of various meso- and micro-topography, there are "multi-centers" in the pressurefield, and the dominant wind field is "disordered": the temperatures on the convexi-concave orog-raphy and sun-shady slope are different significantly. There is cold advection in the east side,which can reaches the ground and the air pressure field is a "unity". The wind field is dominated bythe west wind. The temperature differences of various slope directions are small, and becomesmaller with height. (b) In summer, the upper control flow (planetary west wind) becomes weak-er, and the orographic air pressure centers in the east develop. Over the windward side of themountain high pressure prevails, and over the lee side low pressure does. These areas becomedeserts for dryness and lack of rainfall. Air temperature in summer can be expressed by latitude,longitude and elevation.     

偏北大风的数值预报释用方法研究

本文利用欧洲中心中期数值预报结果，从不同侧面选取因子，建立了日最大平均风速的四种统计预报方程，在此基础上设计了几种集成方法对预报结果进行集成，结果表明，我们设计的最大值－阀值综合集成法取得了很好的效果，特别是2－3天的大风预报准确度较高。     

STUDY OF PHYSICAL PROCESSES AFFECTING THE TRANSFORMATION OF COLD AIR OVER LAND AFTER OUTBREAK OF COLD WAVES IN EAST ASIA

Authors have studied the transformation processes of cold air over land in East Asia for eight cases which occurredin different months of 1981.First,the surface eddy sensible and latent heat fluxes,and drag coefficient were estimatedaccording to the approach of similarity theory.Then,the apparent heat source,the apparent moisture sink,and solarand long-wave radiative heating(or cooling)were further calculated through the budget method and physicalparameterization algorithm.It has been found that the cold air immediately starts the transformation process over landonce it moves away from its region of origin.In winter,the degree of transformation of cold air mass gradually intensi-fied as it travelled southeastward;while arriving in the ocean,the cold air mass underwent the most significant transfor-mation process.In summer,the most vigorous transformation of thermal and moisture fields was observed in NorthChina and Mongolian region,with much greater intensity than that in winter.     

BASIC CHARACTERISTICS OF SURFACE WIND. PRESSURE AND TEMPERATURE IN PLATEAU OF MONGOLIA*

After analyzing the mean pressure, dominant wind and temperature data of 40 observation stations in Mongolia from 1961 to 1990, we reach some conclusions as below: (a) The warm advection in the free atmosphere hardly reaches the ground in the west in winter. Because of thermodynamic differences of various meso- and micro-topography, there are "multi-centers" in the pressure field, and the dominant wind field is "disordered": the temperatures on the convexi-concave orography and sun-shady slope are different significantly. There is cold advection in the east side,which can reaches the ground and the air pressure field is a "unity". The wind field is dominated by the west wind. The temperature differences of various slope directions are small, and become smaller with height. (b) In summer, the upper control flow (planetary west wind) becomes weaker, and the orographic air pressure centers in the east develop. Over the windward side of the mountain high pressure prevails, and over the lee side low pressure does. These areas become deserts for dryness and lack of rainfall. Air temperature in summer can be expressed by latitude,longitude and elevation.