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A Three-dimensional Wave Activity Flux of Inertia–Gravity Waves and Its Application to a Rainstorm Event

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Advances in atmospheric sciences 2019年第2期36卷 206-218页

作者： Lu LIU lingkun ran shouting gao state key laboratory of Severe Weather Chinese Academy of Meteorological Sciences institute of atmosphere physics Chinese Academy Sciences

A three-dimensional transformed Eulerian-mean(3D TEM) equation under a non-hydrostatic and non-geostrophic assumption is deduced in this study. The vertical component of the 3D wave activity flux deduced here is the primary difference from previous studies, which is suitable to mesoscale systems. Using the 3D TEM equation, the energy propagation of the inertia–gravity waves and how the generation and dissipation of the inertia–gravity waves drive the mean flow can be examined. During the mature stage of a heavy precipitation event, the maximum of the Eliassen–Palm(EP) flux divergence is primarily concentrated at the height of 10–14 km, where the energy of the inertia–gravity waves propagates forward(eastward) and upward. Examining the contribution of each term of the 3D TEM equation shows that the EP flux divergence is the primary contributor to the mean flow tendency. The EP flux divergence decelerates the zonal wind above and below the high-level jet at the height of 10 km and 15 km, and accelerates the high-level jet at the height of 12–14 km. This structure enhances the vertical wind shear of the environment and promotes the development of the rainstorm.

关键词： three-dimensional EP flux heavy precipitation inertia–gravity waves

The Impact of Deformation on Vortex Development in a Baroclinic Moist atmosphere

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Advances in atmospheric sciences 2016年第2期33卷 233-246页

作者： Na LI lingkun ran shouting gao key laboratory of Cloud-Precipitation physics and Severe Storms Institute of Atmospheric PhysicsChinese Academy of Sciences state key laboratory of Severe Weather Chinese Academy of Meteorological Sciences

A mathematical relation between deformation and vertical vorticity tendency is built by introducing the frontogenesis function and the complete vertical vorticity equation, which is derived by virtue of moist potential vorticity. From the mathematical relation, it is shown that properly configured atmospheric conditions can make deformation exert a positive contribution to vortex development at rates comparable to other favorable factors. The effect of deformation on vortex development is not only related to the deformation itself, but also depends on the current thermodynamic and dynamic structures of the atmosphere, such as the convective stability, moist baroclinicity and vertical wind shear （or horizontal vorticity）. A diagnostic study of a heavy-rainfall case that occurred during 20-22 July 2012 shows that deformation has the most remarkable effect on the increase in vertical vorticity during the rapid development stage of the low vortex during its whole life cycle. This feature is mainly due to the existence of an approximate neutral layer （about 700 hPa） in the atmosphere where the convective stability tends to be zero. The neutral layer makes the effect of deformation on the vertical vorticity increase significantly during the vortex development stage, and thus drives the vertical vorticity to increase.

关键词： deformation low vortex vorticity frontogenesis function

Analysis of the Characteristics of Inertia-Gravity Waves during an Orographic Precipitation Event

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Advances in atmospheric sciences 2018年第5期35卷 604-620页

作者： Lu LIU lingkun ran shouting gao state key laboratory of Severe Weather Chinese Academy of Meteorological Sciences Beijing 100081 China institute of atmosphere physics Chinese Academy Sciences Beijing 100029 China Heavy Rain and Drought-Flood Disasters in Plateau and Basin key laboratory of Sichuan Province Chengdu 610072 China Plateau atmosphere and Environment key laboratory of Sichuan Province Sichuan 610103 China

A numerical experiment was performed using the Weather Research and Forecasting（WRF） model to analyze the generation and propagation of inertia-gravity waves during an orographic rainstorm that occurred in the Sichuan area on 17 August 2014. To examine the spatial and temporal structures of the inertia-gravity waves and identify the wave types, three wavenumber-frequency spectral analysis methods（Fourier analysis, cross-spectral analysis, and wavelet cross-spectrum analysis）were applied. During the storm, inertia-gravity waves appeared at heights of 10-14 km, with periods of 80-100 min and wavelengths of 40-50 km. These waves were generated over a mountain and propagated eastward at an average speed of 15-20 m s^（-1）. Meanwhile, comparison between the reconstructed inertia-gravity waves and accumulated precipitation showed there was a mutual promotion process between them. The Richardson number and Scorer parameter were used to demonstrate that the eastward-moving inertia-gravity waves were trapped in an effective atmospheric ducting zone with favorable reflector and critical level conditions, which were the primary causes of the long lives of the waves. Finally, numerical experiments to test the sensitivity to terrain and diabatic heating were conducted, and the results suggested a cooperative effect of terrain and diabatic heating contributed to the propagation and enhancement of the waves.

关键词： inertia-gravity waves orographic precipitation Fourier analysis wavelet cross-spectrum analysis

Evolution of Instability before and during a Torrential Rainstorm in North china

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Advances in atmospheric sciences 2016年第1期33卷 110-120页

作者： Lu LIU lingkun ran shouting gao institute of atmospheric physics Chinese Academy Sciences Beijing 100029 Graduate University of chinese academy of sciences Beijing 100040 state key laboratory of Severe Weather Chinese Academy of Meteorological Sciences Beijing 100081

NCEP-NCAR reanalysis data were used to analyze the characteristics and evolution mechanism of convective and symmetric instability before and during a heavy rainfall event that occurred in beijing on 21 July *** twelve hours before the rainstorm,the atmosphere was mainly dominated by convective instability in the lower level of 900-800 *** strong southwesterly low-level jet conveyed the moist and warm airflow continuously to the area of torrential rain,maintaining and enhancing the unstable *** the precipitation occurred,unstable energy was released and the convective instability ***,due to the baroclinicity enhancement in the atmosphere,the symmetric instability strengthened,maintaining and promoting the subsequent torrential *** the convective instability tendency equation demonstrated that the barotropic component of potential divergence and the advection term played a major role in enhancing the convective instability before the *** of the tendency equation of moist potential vorticity showed that the coupled term of vertical vorticity and the baroclinic component of potential divergence was the primary factor influencing the development of symmetric instability during the *** the effects of these factors on convective instability and symmetric instability showed some correlation.

关键词： convective instability symmetric instability torrential rain potential divergence

Potential Deformation and Its Application to the Diagnosis of Heavy Precipitation in Mesoscale Convective Systems

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Advances in atmospheric sciences 2017年第7期34卷 894-908页

作者： Na LI lingkun ran Linna ZHANG shouting gao key laboratory of Cloud-Precipitation physics and Severe Storms Institute of Atmospheric Physics Chinese Academy of Sciences BeOing 100029 China state key laboratory of Severe Weather Chinese Academy of Meteorological Sciences Beijing 100081 China beijing Meteorological Bureau Beijing 100089 China

Many observational studies have shown that deformation, like vertical vorticity and divergence, is closely related to the occurrence and distribution of strong precipitation. In this paper, to involve deformation in precipitation diagnosis, a new parameter called potential deformation（PD） is derived and then applied to precipitation detection within a simulated mesoscale convective system（MCS）. It is shown that PD includes both stretching deformation and shearing deformation and shares similar characteristics with deformation insofar as it does not change with the rotating coordinate. Diagnosis of the simulated MCS reveals that PD performs well in tracing the MCS＇ precipitation. In terms of their distributional pattern, the large-value areas of PD are similar to the precipitation in the different development stages of the MCS. A detailed analysis of the physical processes contained within the PD shows that it can reflect the three-dimensional moisture variation,vertical wind shear and wind deformation within the MCS. These structures are usually a comprehensive reflection of the characteristics of the surface cold pool, rear inflow jet, downward cold air flow and upward warm moist flow within the precipitating convective cells. For this reason, the PD shows much stronger anomalies in the precipitating atmosphere than the non-precipitating atmosphere, which implies considerable potential for its application in detecting heavy precipitation within MCSs.

关键词： Precipitation convective vorticity moisture divergence mesoscale observational stretching downward coordinate

Proof of the Monotonicity of Grid Size and Its Application in Grid-Size Selection for Mesoscale Models

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Advances in atmospheric sciences 2015年第7期32卷 1005-1015页

作者： WANG Chengxin gao shouting ran lingkun LIANG Li laboratory of Cloud-Precipitation physics and Severe Storms Institute of Atmospheric PhysicsChinese Academy of Sciences University of chinese academy of sciences state key laboratory of Severe Weather Chinese Academy of Meteorological Sciences Public Weather Service Center China Meteorological Administration National Meteorological Center China Meteorological Administration

Terrain characteristics can be accurately represented in spectrum space. Terrain spectra can quantitatively reflect the effect of topographic dynamic forcing on the atmosphere. In wavelength space, topographic spectral energy decreases with decreasing wavelength, in spite of several departures. This relationship is approximated by an exponential function. A power law relationship between the terrain height spectra and wavelength is fitted by the least-squares method, and the fitting slope is associated with grid-size selection for mesoscale models. The monotonicity of grid size is investigated, and it is strictly proved that grid size increases with increasing fitting exponent, indicating that the universal grid size is determined by the minimum fitting exponent. An example of landslide-prone areas in western Sichuan is given, and the universal grid spacing of 4.1 km is shown to be a requirement to resolve 90% of terrain height variance for mesoscale models, without resorting to the parameterization of subgrid-scale terrain variance. Comparison among results of different simulations shows that the simulations estimate the observed precipitation well when using a resolution of 4.1 km or finer. Although the main flow patterns are similar, finer grids produce more complex patterns that show divergence zones, convergence zones and vortices. Horizontal grid size significantly affects the vertical structure of the convective boundary layer. Stronger vertical wind components are simulated for finer grid resolutions. In particular, noticeable sinking airflows over mountains are captured for those model configurations.

关键词： terrain spectra monotonically increasing function fitting exponent the universal grid size model sensitivity

Organized Warm-Sector Rainfall in the Coastal Region of South china in an Anticyclone Synoptic Situation:Observational Analysis

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Journal of Meteorological Research 2021年第3期35卷 460-477页

作者： Zhaoming LIANG shouting gao state key laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081 Southern Marine Science and Engineering Guangdong laboratory(Zhuhai) Zhuhai 519082 institute of atmospheric physics Chinese Academy of SciencesBeijing 100029 University of chinese academy of sciences Beijing 100049

Organized warm-sector rainfall(OWSR)near the coast of South china tends to occur in certain synoptic situations characterized with either a low-level jet or an anticyclone,with the latter being less *** paper fills the gap by analyzing 15 OWSR events that occurred in an anticyclone synoptic situation during the pre-summer rainy season of 2011-2016,based on high-resolution observational and reanalysis *** results show that the anticyclone synoptic situation produces marked northerly boundary-layer winds inland and obvious northeasterly,easterly/southwesterly,and southeasterly boundary-layer winds near the coasts of eastern Guangdong,western Guangdong,and Guangxi,*** coastal boundary-layer winds promote favorable environmental conditions and strong convergence for convection initiation;consequently,OWSR is prone to occur near the coasts of western Guangdong and Guangxi,but exhibits different formation and propagation features in the following two subareas.(1)The southeasterly boundary-layer winds tend to converge near the border area between Guangxi and Guangdong(BGG),promoting the formation of a stable convective line along the *** convective line persists with support of upper-level southwesterly winds that facilitate convective cells to propagate along the convective line,producing heavy OWSR along the mountains near BGG.(2)In contrast,a west-east convective line tends to form and maintain near the coast of Yangjiang(YJ)area,about 200 km east of BGG,owing to stable convergence between the easterly(or southwesterly)and the northerly boundary-layer winds reinforced by the mountains near ***,the coupling of upper-level westerly winds with the easterly(southwesterly)boundary-layer winds facilitates expansion(eastward propagation)of the convective line,causing west-east-oriented heavy OWSR near the coast of *** a word,this study reveals refined properties of OWSR initiation and development in the anticyclone synoptic s

关键词： organized warm-sector rainfall(OWSR) anticyclone synoptic situation formation South china

Reinvestigation of potential deformation during a heavy rainfall event in North china

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atmospheric and Oceanic Science Letters 2020年第5期13卷 407-416页

作者： LI Na ran lingkun HU Jianhua gao shouting key laboratory of Cloud-Precipitation physics and Severe Storms Institute of Atmospheric PhysicsChinese Academy of SciencesBeijingChina Meteorological Disaster Prevention Technology Center of Jilin Province Jilin Meteorological ServiceJilinChina Guizhou key Lab of Mountounious Climate&Resources Guizhou Institute of Mountain Environment and ClimateGuizhou Meteorological BureauGuiyangChina

In this study,the physical meaning and generation mechanism of potential deformation(PD)are reinvestigated.A main trait of PD is that it contains deformation,which is an important factor to precipitation but not well applied in precipitation *** paper shows PD shares similar features to deformation,but contains much more physical information than *** can be understood as a type of deformation of a thermodynamic-coupled vector(u*,v*).For convenient application,squared PD(SPD)is used instead for *** deriving the tendency equation of SPD,it is found that whether SPD is produced or reduced in the atmosphere is associated with the angle between the dilatation axes of PD and geostrophic *** the angle is less thanπ2,SPD is *** diagnostic results during a heavy rainfall event in North china on 20 July 2016 show that the process of rapid increase in precipitation can be well revealed by *** distribution of SPD becomes more organized and concentrated with increasing precipitation intensity.A diagnostic analysis of the SPD tendency equation shows that concentrated SPD is associated with the generation of SPD in the boundary layer followed by upward transport of the *** concentration of SPD indicates a confluence of precipitation-favorable factors—namely,vertical wind shear and moist baroclinity,which can enhance vertical motions and thus cause an increase in *** diagnostic results further verify PD as a useful physical parameter for heavy precipitation diagnosis.

关键词： Deformation potential deformation heavy precipitation

Meteorological impacts on evapotranspiration in different climatic zones of Pakistan

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Journal of Arid Land 2017年第6期9卷 938-952页

作者： Shahzada ADNAN Kalim ULLAH Azmat H KHAN gao shouting Department of Meteorology COMSATS Institute of Information Technology Islamabad 44000 Pakistan Pakistan Meteorological Department Islamabad 44000 Pakistan state key laboratory of Cloud-Precipitation physics and SevereStorms Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

Arid regions are highly vulnerable and sensitive to drought. The crops cultivated in arid zones are at high risk due to the high evapotranspiration and water demands. This study analyzed the changes in seasonal and annual evapotranspiration（ET） during 1951–2016 at 50 meteorological stations located in the extremely arid, arid, and semi-arid zones of Pakistan using the Penman Monteith（PM） method. The results show that ET is highly sensitive and positively correlated to temperature, solar radiation, and wind speed whereas vapor pressure is negatively correlated to ET. The study also identifies the relationship of ET with the meteorological parameters in different climatic zones of Pakistan. The significant trend analysis of precipitation and temperature（maximum and minimum） are conducted at 95% confidence level to determine the behaviors of these parameters in the extremely arid, arid, and semi-arid zones. The mean annual precipitation and annual mean maximum temperature significantly increased by 0.828 mm/a and 0.014℃/a in the arid and extremely arid zones, respectively. The annual mean minimum temperature increased by 0.017℃/a in the extremely arid zone and 0.019℃/a in the arid zone, whereas a significant decrease of 0.007℃/a was observed in the semi-arid zone. This study provides probabilistic future scenarios that would be helpful for policy-makers, agriculturists to plan effective irrigation measures towards the sustainable development in Pakistan.

关键词： evapotranspiration meteorological parameters climatic zone Penman Monteith method Pakistan