AN INTEGRATION METHOD WITH FITTING CUBIC SPLINE FUNCTIONS TO A NUMERICAL MODEL OF 2ND-ORDER SPACE-TIME DIFFERENTIAL REMAINDER——FOR AN IDEAL GLOBAL SIMULATION CASE WITH PRIMITIVE ATMOSPHERIC EQUATIONS

In this paper,the forecasting equations of a 2nd-order space-time differential remainder are deduced from the Navier-Stokes primitive equations and Eulerian operator by Taylor-series expansion.Here we introduce a cubic spline numerical model(Spline Model for short),which is with a quasi-Lagrangian time-split integration scheme of fitting cubic spline/bicubic surface to all physical variable fields in the atmospheric equations on spherical discrete latitude-longitude mesh.A new algorithm of"fitting cubic spline—time step integration—fitting cubic spline—……"is developed to determine their first-and2nd-order derivatives and their upstream points for time discrete integral to the governing equations in Spline Model.And the cubic spline function and its mathematical polarities are also discussed to understand the Spline Model’s mathematical foundation of numerical analysis.It is pointed out that the Spline Model has mathematical laws of"convergence"of the cubic spline functions contracting to the original functions as well as its 1st-order and 2nd-order derivatives.The"optimality"of the 2nd-order derivative of the cubic spline functions is optimal approximation to that of the original functions.In addition,a Hermite bicubic patch is equivalent to operate on a grid for a 2nd-order derivative variable field.Besides,the slopes and curvatures of a central difference are identified respectively,with a smoothing coefficient of 1/3,three-point smoothing of that of a cubic spline.Then the slopes and curvatures of a central difference are calculated from the smoothing coefficient 1/3 and three-point smoothing of that of a cubic spline,respectively.Furthermore,a global simulation case of adiabatic,non-frictional and"incompressible"model atmosphere is shown with the quasi-Lagrangian time integration by using a global Spline Model,whose initial condition comes from the NCEP reanalysis data,along with quasi-uniform latitude-longitude grids and the so-called"shallow atmosphere"Navier-Stokes primitive equations in the spherical coordinates.The Spline Model,which adopted the Navier-Stokes primitive equations and quasi-Lagrangian time-split integration scheme,provides an initial ideal case of global atmospheric circulation.In addition,considering the essentially non-linear atmospheric motions,the Spline Model could judge reasonably well simple points of any smoothed variable field according to its fitting spline curvatures that must conform to its physical interpretation.     

Classification of Northeast China Cold Vortex Activity Paths in Early Summer Based on K-means Clustering and Their Climate Impact

The classification of the Northeast China Cold Vortex(NCCV)activity paths is an important way to analyze its characteristics in detail.Based on the daily precipitation data of the northeastern China(NEC)region,and the atmospheric circulation field and temperature field data of ERA-Interim for every six hours,the NCCV processes during the early summer(June)seasons from 1979 to 2018 were objectively identified.Then,the NCCV processes were classified using a machine learning method(k-means)according to the characteristic parameters of the activity path information.The rationality of the classification results was verified from two aspects,as follows:(1)the atmospheric circulation configuration of the NCCV on various paths;and(2)its influences on the climate conditions in the NEC.The obtained results showed that the activity paths of the NCCV could be divided into four types according to such characteristics as the generation origin,movement direction,and movement velocity of the NCCV.These included the generation-eastward movement type in the east of the Mongolia Plateau(eastward movement type or type A);generation-southeast longdistance movement type in the upstream of the Lena River(southeast long-distance movement type or type B);generationeastward less-movement type near Lake Baikal(eastward less-movement type or type C);and the generation-southward less-movement type in eastern Siberia(southward less-movement type or type D).There were obvious differences observed in the atmospheric circulation configuration and the climate impact of the NCCV on the four above-mentioned types of paths,which indicated that the classification results were reasonable.     

Phase Two of the Integrative Monsoon Frontal Rainfall Experiment (IMFRE-II) over the Middle and Lower Reaches of the Yangtze River in 2020

Phase Two of the Integrative Monsoon Frontal Rainfall Experiment(IMFRE-II)was conducted over the middle and lower reaches of the Yangtze River during the period 16 June to 19 July 2020.This paper provides a brief overview of the IMFRE-II field campaign,including the multiple ground-based remote sensors,aircraft probes,and their corresponding measurements during the 2020 mei-yu period,as well as how to use these numerous datasets to answer scientific questions.The highlights of IMFRE-II are:(1)to the best of our knowledge,IMFRE-II is the first field campaign in China to use ground-based,airborne,and spaceborne platforms to conduct comprehensive observations over the middle and lower reaches of the Yangtze River;and(2)seven aircraft flights were successfully carried out,and the spectra of ice particles,cloud droplets,and raindrops at different altitudes were obtained.These in-situ measurements will provide a“cloud truth”to validate the ground-based and satellite-retrieved cloud and precipitation properties and quantitatively estimate their retrieval uncertainties.They are also crucial for the development of a warm(and/or cold)rain conceptual model in order to better understand the cloud-to-rain conversion and accretion processes in mei-yu precipitation events.Through an integrative analysis of ground-based,aircraft,and satellite observations and model simulations,we can significantly improve our cloud and precipitation retrieval algorithms,investigate the microphysical properties of cloud and precipitation,understand in-depth the formation and dissipation mechanisms of mei-yu frontal systems,and improve cloud microphysics parameterization schemes and model simulations.     

CHARACTERISTICS OF TROPICAL CYCLONES IMPACTING A NUCLEAR POWER PLANT IN SOUTHERN FUJIAN AND ESTIMATE OF MINIMUM CENTRAL PRESSURE

Based on tropical cyclone (TC) data for the period 1949 to 2008 and following the Gumbe-I method, Pearson-Ⅲ method and determinacy method, this article estimates the possible minimum central pressure of TCs affecting southern Fujian where a nuclear power will be located. Results show that the observed minimum central pressure of TCs agrees well with the results determined with the methods above and there is little difference between them (the minimum central pressure is 867.4 hPa and 868.1 hPa, respectively, in a 1,000-yr return period). Established with the theory of atmospheric dynamics, the determinacy method yields a result of 867.28 hPa/1000 years, only a little smaller than the result of the probability method. Because of randomicity in parameter adjustment with the Pearson-Ⅲ method whereas the determinacy method is theoretically solid and its estimates are the smallest of the three methods, it is therefore reasonable, for security and conservative concerns, to adopt the result determined with the determinacy method as the possible maximum intensity of TC (with the central pressure being 867.28 hPa in a 1,000-yr return period).     

A Comparison of Two Bulk Microphysics Parameterizations for the Study of Aerosol Impacts on an Idealized Supercell

Idealized supercell storms are simulated with two aerosol-aware bulk microphysics schemes(BMSs),the Thompson and the Chen-Liu-Reisner(CLR),using the Weather Research and Forecast(WRF)model.The objective of this study is to investigate the parameterizations of aerosol effects on cloud and precipitation characteristics and assess the necessity of introducing aerosols into a weather prediction model at fine grid resolution.The results show that aerosols play a decisive role in the composition of clouds in terms of the mixing ratios and number concentrations of liquid and ice hydrometeors in an intense supercell storm.The storm consists of a large amount of cloud water and snow in the polluted environment,but a large amount of rainwater and graupel instead in the clean environment.The total precipitation and rain intensity are suppressed in the CLR scheme more than in the Thompson scheme in the first three hours of storm simulations.The critical processes explaining the differences are the auto-conversion rate in the warm-rain process at the beginning of storm intensification and the low-level cooling induced by large ice hydrometeors.The cloud condensation nuclei(CCN)activation and auto-conversion processes of the two schemes exhibit considerable differences,indicating the inherent uncertainty of the parameterized aerosol effects among different BMSs.Beyond the aerosol effects,the fall speed characteristics of graupel in the two schemes play an important role in the storm dynamics and precipitation via low-level cooling.The rapid intensification of storms simulated with the Thompson scheme is attributed to the production of hail-like graupel.     

THE IMPACTS OF MADDEN-JULIAN OSCILLATION ON SPRING RAINFALL IN EAST CHINA

Phase composite analyses are conducted to investigate the possible effect of the Madden–Julian oscillation(MJO)on the spring rainfall anomalies in East China by using the Real-time Multivariate MJO(RMM)index from Australian Meteorological Bureau.The results show that the rainfall anomalies over the mid-and lower-valley of Yangtze River are positive when the MJO shifts eastward to the mid-and eastern-Indian Ocean,and anomalous precipitation over South China are positive when the MJO moves further eastward to the maritime continent,whereas spring rainfall anomalies over East China are negative in the other MJO episodes.The MJO impacts on the precipitation over East China result from the changes in large-scale atmospheric circulation as well as vorticity and water vapor transportation in the mid-and lower-troposphere.     

Hydro-climatic Characteristics of Yarlung Zangbo River Basin since the Last Glacial Maximum

Global climate changes significantly impact the water condition of big rivers in glacierized high mountains. However,there is a lack of studies on hydrological changes within river basins caused by climate changes over a geological timescale due to the impossibility of direct observations. In this study, we examine the hydro-climatic variation of the Yarlung Zangbo River Basin in the Tibet Plateau since the Last Glacial Maximum(LGM) by combining δ18 O proxy records in Indian and Omani caves with the simulated Indian summer monsoon, surface temperature, precipitation, evapotranspiration and runoff via the Community Climate System Model and the reconstructed glacier coverage via the Parallel Ice Sheet Model. The mean river runoff was kept at a low level of 145 billion cubic meters per year until an abrupt increase at a rate of 8.7 million cubic meters per year in the B?lling-Aller?d interval(BA). The annual runoff reached a maximum of 250 billion cubic meters in the early Holocene and then reduced to the current value of 180 billion cubic meters at a rate of 6.4 million cubic meters per year. The low runoff in the LGM and Heinrich Stadial 1(HS1) is likely attributed to such a small contribution of precipitation to runoff and the large glacier cover. The percentage of precipitation to runoff was only 20%during the LGM and HS1. Comparison of glacier area among different periods indicates that the fastest deglaciation occurred during the late HS1, when nearly 60% of glacier area disappeared in the middle reach, 50% in the upper reach,and 30% in the lower reach. The rapid deglaciation and increasing runoff between the late HS1 and BA may have accelerated widespread ice-dam breaches and led to extreme outburst flood events. Combining local geological proxy records and regional simulations could be a useful approach for the study of paleo-hydrologic variations in big river basins.     

Verification of Subseasonal-to-Seasonal Forecasts for Major Stratospheric Sudden Warmings in Northern Winter from 1998/99 to 2012/13

This study reports verification results of hindcast data of four systems in the subseasonal-to-seasonal(S2 S) prediction project for major stratospheric sudden warmings(MSSWs) in northern winter from 1998/99 to 2012/13. This report deals with average features across all MSSWs, and possible differences between two MSSW types(vortex displacement and split types). Results for the average features show that stratospheric forecast verifications, when further averaged among the four systems, are judge...     

南京三千公尺高空之风向与天气之预测

晚近日本籐原笑平(Fujiwhora)博士于地球物理杂志发表「根据三千公尺高空等压线,以预测天气之一例证」一文,谓日本最近用三千公尺高空之等压线,作每日天气之预测,已得相当成就。氏之经验法则谓自九月以迄五月,日本太平洋沿岸,三千公尺高空之等压线,来自西南者,可形去致雨,而来自西北者,则可期晴明。此种倾向颇为显著。     

Causes of the Extreme Hot Midsummer in Central and South China during 2017:Role of the Western Tropical Pacific Warming

This study investigates why an extreme hot midsummer occurred in Central and South China(CSC) during 2017. It is shown that the western North Pacific subtropical high(WNPSH) was abnormally intensified and westward-extending,resulting in anomalous high pressure and consequent extreme heat over CSC. The abnormal WNPSH was favored by the warming of the western tropical Pacific(WTP), which was unrelated to ENSO and manifested its own individual effect.The WTP warming enhanced the convection in-situ and led to anomalous high pressure over CSC via a local meridional circulation. The influence of the WTP was confirmed by CAM4 model experiments. A comparison between the 2017 midsummer and 2010 midsummer(with a stronger WNPSH but weaker extreme heat) indicated that the influence of the WNPSH on extreme heat can be modulated by the associated precipitation in the northwestern flank.The role of the WTP was verified by regression analyses on the interannual variation of the WTP sea surface temperature anomaly(SSTA). On the other hand, the WTP has undergone prominent warming during the past few decades, resulting from decadal to long-term changes and favoring extreme warm conditions. Through a mechanism similar to the interannual variation, the decadal to long-term changes have reinforced the influence of WTP warming on the temperature over CSC,contributing to the more frequent hot midsummers recently. It is estimated that more than 50% of the temperature anomaly over CSC in the 2017 midsummer was due to the WTP warming, and 40% was related to the decadal to long-term changes of the WTP SSTA.     

改进气象服务手段提高公众服务效益──纪念1995年世界气象日

公众气象服务是国家中心的重点工作，中期数值预报业务先进的计算机自动化通信系统的建立国家气象中心初步形成了以数值天气预报为基础，以人机交互工作站为主要手段，综合应用多种气象信息的业务服务系统，使天气预报服务水平不断提高，取得显著社会经济效益，气象服务的总体经济效益已达到国家对气象事业投资的４０倍。     

山东决策气象服务的Web服务系统

山东决策气象服务中的Web服务系统，采用多种网络技术将气象综合信息及决策建议，以快捷、通谷易懂的方式向领导部门提供决策服务。本文主要介绍其工作环境、主页的设计风格、框架结构、主要特点及功能等。     

综合信息服务平台在内蒙古气象业务中的应用

构建气象业务信息服务平台,形成内蒙古气象行业内部统一的数据共享服务平台,是内蒙古自治区气象信息化建设的重要任务之一。文章首先描述了平台总体设计、软件配置项架构设计以及功能模块设计;然后对大用户并发访问、数据可视化、大数据应用等关键技术作了阐述;最后,基于上述关键技术对内蒙古气象业务综合信息服务平台进行了实现。目前,该平台已投入运行,效果良好,有效支撑了自治区、盟市、旗县三级用户的业务工作。     

乌海市气象服务系统

文章采用ArcGis地图引擎、VS2010、SQL Server2008软件、B/S+C/S的模式设计开发,在windows xp,2003server,windows 7等环境下可安装运行。该系统以决策服务工作流程为基础,集资料查询、统计、分析、服务产品制作于一体,实现了方便、快捷地查询气象资料、制作各类决策气象服务产品,解决了人工统计资料耗时费力、服务产品制作不规范的问题,大大提高了工作效率,在实际业务服务工作中发挥了很大的作用,具有推广使用价值。     

宁夏旅游气象服务效益评估和服务需求调查

利用专家评估法对2010年宁夏旅游气象服务效益和需求进行评估调查,结果表明:宁夏旅游气象服务效益贡献率为0.203％,效益值为1075.9万元;高敏感气象条件有降雨、降雪、风力、道路结冰、沙尘天气、雾霾、积雪深度、闪电雷暴等;高影响气象要素临界值和有效预报时段因要素和典型服务环节的不同而有所差异;旅游气象服务产品类型包括灾害防御措施科普产品和以基本天气预报和灾害天气预警为主的精细化旅游气象专题服务产品两类,形式仍主要以文字为主,达到74％,发布途经呈手机短信、网络、专用系统、电子邮件等渠道的多元化格局.     

国家气象业务内网WebGIS数据服务系统设计与应用

气象数据服务应当以用户需求为导向,从"我们有什么数据"向"用户需要什么数据"的现代服务方式转变。文章分析了气象数据服务过程中存在的服务效率有待提高、服务方式有待转变等问题,从当前气象数据服务的发展和WebGIS的功能特点入手,提出了WebGIS技术与MUSIC接口相结合的气象数据服务方式。在气象数据服务的过程中,用户不必在多种工具软件间进行复杂的操作,WebGIS技术与气象数据统一服务接口(MUSIC)的结合,实现了集空间位置查找、地理空间分析、浏览器端作图、数据检索、数据下载一站式气象数据服务,该方式简化了气象数据服务过程的复杂度,极大地提高了气象数据服务效率,真正实现了气象数据的"所见即所得,所见可分析"效能,有效提升了国家气象业务内网的用户体验。     

用Web Service收发气象服务小区广播信息应用系统

介绍了气象部门收发小区广播信息的信息交换模式以及Web Service的原理功能.通过分析使用WebService在指定行政区域内和单元网格内发布小区广播信息的详细流程,以及接收网格内当前人口分布数据的方法,证明了使用Web Service的方式收发广播信息的可行性和有效性.采用这种方法后,提高了信息收发的成功率,避免...     

漯河市专业气象服务系统

介绍了漯河市专业气象服务系统的结构及功能.     

对搞好农用气象服务的思考

搞好农用气象服务工作,要做到熟悉和掌握当地的基本情况、基本气候特征、气象灾害和病虫害发生情况、作物生理生态特点、作物气候生态适应性等5个方面的内容。要做到服务形式灵活多样,服务产品针对性强。同时要加强4个基本建设和4个体系建设工作。     

从优秀气象短信存在的问题看当前的气象短信服务

以近几年广西优秀气象短信为例进行分析,找出部分被评为优秀等级的气象短信仍存在不足。并提出相应的解决措施。