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Diagnosis of deformation-derived ascending areas in a rainband

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Atmospheric and Oceanic Science Letters 2018年第4期11卷 300-306页

作者： LI Na RAN Ling-Kun gao shou-ting Key Laboratory of Cloud-Precipitation Physics and Severe Storms Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina Plateau Atmosphere and Environment Key Laboratory of Sichuan Province SichuanChina

This paper demonstrates that,for a moist baroclinic frontal system,the large-value deformation belt in the low-level atmosphere overlaps with *** precisely describe the relationship between deformation and heavy precipitation,deformation is introduced into the nongeostrophic Q^#-vector.Q^#is then decomposed into three parts:the divergence-related term,the vorticity-related term,and the deformation-related *** calculating the divergence of Q#and its components,it is found that in strong ascending areas within precipitation regions the nongeostrophic Q^#-vector divergence shows strong negative *** deformational component can contribute about 68%to these negative *** verifies that strong deformation in a precipitating atmosphere is favorable for the development of convection and *** addition,by calculating the correlation coefficients between the Q^#-vector(including its components)divergence and vertical motions,it is also found that the Q^#-vector divergence shows higher correlation with vertical motion within the precipitation belt and lower correlation in the non-precipitation areas,which indicates a larger contribution of Q^#to vertical motion when precipitation occurs and implies an effect of Q^#to the precipitation distribution or spatial *** the three components of the Q^#-vector,the correlation coefficients between the deformational component and vertical motion are the most similar in pattern to that of the correlation coefficients between the Q#-vector and vertical motion,which further reflects the important contribution of deformation to the large spatial variability of precipitation.

关键词： Deformation Q-vector precipitation ascending motion

Investigating the initiation and propagation processes of convection in heavy precipitation over the western Sichuan Basin

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Atmospheric and Oceanic Science Letters 2017年第3期10卷 235-242页

作者： LI Qin YANG Shuai CUI Xiao-Peng gao shou-ting Laboratory of Cloud-Precipitation Physics and Severe Storms (LACS) Institute of Atmospheric Physics Chinese Academy of Sciences College of Earth Science University of Chinese Academy of Sciences Plateau Atmosphere and Environment Key Laboratory of Sichuan Province (PAEKL) Chengdu University of Information Technology

Heavy precipitation events occur often over the western Sichuan Basin in summer, near the transition zone between the Sichuan Basin and the steep terrain of the Tibetan Plateau. One such event -- a heavy precipitation process that occurred on 18-20 August 2010, with clear nocturnal peaks -- is chosen as a case to tentatively explore how the convection associated with convectivescale precipitation is initiated and propagated. By utilizing the vertical momentum equation from the viewpoint of separating perturbation pressure into dynamic and thermal parts, it is demonstrated that the vertical momentum is induced by the imbalance of several forces, including the dynamic/buoyant part of the perturbation pressure gradient force and the buoyancy force, with the latter dominating during the nocturnal-peak period. Although a negative value of the dynamic perturbation pressure gradient force partly offsets the positive buoyant forcing inside the strong updraft, the pattern of vertical motion tendency is largely attributable to its buoyancy because of its larger magnitude. Relative to the buoyancy component, the dynamic part of the vertical perturbation pressure gradient is also examined, revealing a smaller order of magnitude. Thus, it is the thermal effect that should be responsible for the initiation and propagation of convection. As for the convective-scale precipitation, it always presents a trailing morphology relative to the strong leading-side updraft. Furthermore, overlapping strong signals of vertical motion and its tendency point towards strong precipitation in the future.

关键词： Heavy precipitation convection vertical momentum equation perturbation pressure equation

A Brief Report of Graphic Explanations for Generalized Potential Temperature in the Non-Uniformly Saturated Atmosphere

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Atmospheric and Oceanic Science Letters 2011年第3期4卷 162-167页

作者： CAO Jie ZHOU Yu-Shu gao shou-ting Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

Compared to potential temperature （θ） in the dry atmosphere and equivalent potential temperature （θc） in the saturated atmosphere, generalized potential tem- perature （θ＂） has already proven a better thermodynamic parameter in describing the non-uniformly saturated real atmosphere. To add otherwise absent graphic explanations, this paper first presents the physical definition of θ through a tephigram. Then, the utility of the measurement in identifying and forecasting the locations of precipita- tion maxima and heat wave areas with diagnostic com- parison studies and traditionally used thermodynamic parameters is shown.

关键词： generalized potential temperature physicalgraph thermodynamic parameters

The Seasonal and Interannual Variation of Diurnal Precipitation over the Tibetan Plateau and Its Downstream Regions Observed by the Tropical Rainfall Measuring Mission

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Atmospheric and Oceanic Science Letters 2015年第6期8卷 365-370页

作者： HU Liang DENG Di-Fei gao shou-ting LI Yao-Dong State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences Institute of Atmospheric Physics Chinese Academy of Sciences Beijing Aviation Meteorological Institute

Using nine years of Tropical Rainfall Measuring Mission(TRMM)2A25 data,based on the probability density function of rainfall,a comparative analysis of the diurnal cycle and its seasonal and interannual variation for convective rain,stratiform rain,and total rain is made between the Tibetan Plateau and the downstream Yangtze River basin and East China *** diurnal convective rain is stronger than the diurnal stratiform rain over the Yangtze River basin,and the convective rain peaks in the afternoon when the stratiform rain maximum happens in the early *** rain and stratiform rain both peak in the early morning over the East China *** diurnal total rain over the Tibetan Plateau is stronger than its downstream *** diurnal cycle appears quite different among the four seasons over the Yangtze River basin,and the seasonal variation of diurnal convective rain is more apparent than diurnal stratiform *** seasonal variation of the diurnal cycle is weak over the East China Sea and Tibetan *** maximum of total rain happens in the afternoon during1998–2002 over the Yangtze River basin,while it peaks in the early morning during 2003–2006,but no obvious phase differences can be found among years in the diurnal rain over the East China Sea and over the Tibetan Plateau.

关键词： diurnal cycle convective rain stratiform rain Tibe

A Numerical Study of the Urban Intensity Effect on Fog Evolution in the Beijing-Tianjin-Hebei Region

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Atmospheric and Oceanic Science Letters 2012年第3期5卷 240-245页

作者： LIANG Zhao-Ming gao shou-ting SUN Ji-Song Laboratory of Cloud-Precipitation Physics and Severe Storms （LACS） Institute of Atmospheric Physics Chinese Academy of Sci- ences Beijing 100029 China Graduate University of Chinese Academy of Sciences Beijing 100049 China Beijing Meteorological Bureau Beijing 100089 China

The influence of urban intensity on fog evolution in the Beijing-Tianjin-Hebei (BTH) region (China) is investigated numerically with the the Weather Research and Forecasting (WRF) model coupled with the urban canopy parameterization-building energy model (UCP- BEM) urban physics scheme. The experiments were designed with a focus on the influence of different urban intensities, which are represented by a different fractional coverage of natural land, buildings, and energy consumption inside buildings in an urban environment. The results of this study indicate that urban areas notably influence fog evolution when natural land is reduced to a small fraction (e.g., less than 10%). Developed land changes fog evolution through urban effects. Higher urban intensity (HUI) generally results in warmer temperatures and lower wind speeds throughout the day, while inhibiting morning specific humidity loss and afternoon specific humidity gain because of the HUI effect on surface heat flux, surface roughness, and surface moisture flux. HUI leads to later and weaker liquid water content formation, with a higher liquid water content base, primarily due to its effect on near surface temperatures. This finding implies that HUI may inhibit the conditions for fog formation. In addition, urban areas with equal natural and developed land coverage seem to greatly enhance the upward surface moisture flux, which is attributed to the combination of a relatively large potential evaporation on developed land and an ample moisture supply from natural land. As a result, the specific humidity increases in the afternoon.

关键词： numerical study urban intensity effect fog the Beijing-Tianjin-Hebei region

Kinetic Energy Budget Equations of Rotational and Divergent Flow in Terrain-following Coordinates

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Atmospheric and Oceanic Science Letters 2013年第3期6卷 149-153页

作者： CAO Jie SUN Ji-Song gao shou-ting CUI Xiao-Peng Institute of Atmospheric Physics Chinese Academy of Sciences Beijing Meteorological Bureau

In this study, kinetic energy budget equations of rotational and divergent flow in pressure coordinates are derived on terrain-following coordinates. The new formulation explicitly shows the terrain effects and can be applied directly to model-simulated dynamic and thermodynamic fields on the model's original vertical grid. Such application eliminates interpolation error and avoids errors in virtual weather systems in mountainous areas. These advantages and their significance are demonstrated by a numerical study in terrain-following coordinates of a developing vortex after it moves over the Tibetan Plateau in China.

关键词： terrain-following coordinates kinetic energy southwest vortex streamfunction velocity potential

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非均匀饱和大气中的广义位温

地球物理学报 2008年第6期51卷 1651-1656页

作者：曹洁高守亭中国科学院大气物理研究所云降水物理与强风暴实验室LACS 北京100029 中国科学院研究生院北京100049

从热力学第一定律出发证明了广义位温的物理基础及其守恒性,完善了gao等在2004年提出的非均匀饱和大气动力学的理论基础.探讨了广义湿位涡理论及其倾向方程在地面气旋追踪、雾区预报等方面的可应用性,为湿空气动力学的理论研究和业务应... 详细信息

从热力学第一定律出发证明了广义位温的物理基础及其守恒性,完善了gao等在2004年提出的非均匀饱和大气动力学的理论基础.探讨了广义湿位涡理论及其倾向方程在地面气旋追踪、雾区预报等方面的可应用性,为湿空气动力学的理论研究和业务应用提供了新思路.结果表明,非均匀饱和大气中的广义位温和位温、相当位温一样,具有守恒性;但由于其体现了实际大气的非均匀饱和特性,比位温、相当位温具有更广泛的应用前景.

关键词：广义位温非均匀饱和湿空气动力学

水汽螺旋度和热力螺旋度在华北强“桑拿天”过程中的分析及应用

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地球物理学报 2013年第7期56卷 2185-2194页

作者：杨帅陈斌高守亭中国科学院大气物理研究所云降水物理与强风暴实验室北京100029 中国气象科学研究院灾害天气国家重点实验室北京100081

"桑拿天"是发生在夏季高温、高湿环境之下的重要天气现象.而过去单靠温度这一变量来诊断预报"桑拿天",有较大难度.而且从已有的研究中,"桑拿天"多发生在下沉运动或相对稳定的环流背景下.因此,寻找一个简单有效、且使用方便的物理变量来... 详细信息

"桑拿天"是发生在夏季高温、高湿环境之下的重要天气现象.而过去单靠温度这一变量来诊断预报"桑拿天",有较大难度.而且从已有的研究中,"桑拿天"多发生在下沉运动或相对稳定的环流背景下.因此,寻找一个简单有效、且使用方便的物理变量来揭示"桑拿天"高湿、高湿的综合特征,显得特别重要.本文在前人研究的基础上,将以往暴雨研究中的IM(Ingredients-based Methodology)理论方法拓展至"桑拿天"的研究,将过去表征桑拿天高温、高湿、下沉运动环流特点的这些单个物理量综合进IM方法,尝试性地引入热力螺旋度(TH)、水汽螺旋度(MH)、以及湿热力螺旋度(MTH)等,对发生在2002年7月30日—8月4日和2009年7月7—9日的两次华北地区高温高湿的强"桑拿天"过程进行动力识别和诊断,并与广义湿位涡(GMPV)进行对比分析.分析结果表明,MH的异常大值区相对集中在北京及其周边的华北地区的对流层低层,并维持.而TH的异常大值区涵盖的范围远大于我们要研究的华北地区"桑拿天"的爆发范围.即使结合了温、湿效应的MTH和GMPV的异常大值区,其涵盖的范围亦逊于MH对"桑拿天"的动力识别.可见,在夏季普遍高温的大环境下,湿度是华北闷热的"桑拿天"爆发的一个决定性因素.结合了环流特征与湿度效应的MH,是对"桑拿天"进行动力识别的一个优化因子,具有较大的实际应用价值.

关键词： “桑拿天” 水汽螺旋度热力螺旋度

一次北京大暴雨过程低空东南风气流形成机制的数值研究

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地球物理学报 2010年第6期53卷 1284-1294页

作者：盛春岩高守亭山东省气象科学研究所济南250031 中国科学院大气物理研究所云降水物理与强风暴实验室北京100029

2002年6月24～25日,北京门头沟附近发生了一次大暴雨过程.观测资料和数值模拟均发现,在暴雨发生前和发生过程中,北京地区边界层内出现了一支强盛的东南风气流.东南风气流沿太行山东坡爬升,触发了对流.为探讨这支低空东南风气流的形成原... 详细信息

2002年6月24～25日,北京门头沟附近发生了一次大暴雨过程.观测资料和数值模拟均发现,在暴雨发生前和发生过程中,北京地区边界层内出现了一支强盛的东南风气流.东南风气流沿太行山东坡爬升,触发了对流.为探讨这支低空东南风气流的形成原因,本文通过数值模拟和敏感性试验,对这支东南风气流的形成机制进行了研究.结果表明,这支低层东南风气流是一支冷湿的、伴有较强风速辐合的气流,主要是在天气尺度系统作用下生成的.东南风气流形成过程中,地表感热加热作用对其强度有加强作用.大暴雨开始后的潜热加热作用对这支东南风气流有正反馈作用,使气流的强度大大增强,因此,在降水开始后气流强度也增强,降水最强时低空急流的强度达最强.暴雨开始后,由于夜间地表降温造成山风效应,导致在北京西部山脚下出现偏北风.

关键词：北京大暴雨低空东南风形成原因数值模拟