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.     

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(S2S)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 judged to be successful for lead times around 10 d or shorter.All systems are skillful for lead times around 5 d,whereas the results vary among the systems for longer lead times.A comparison between the MSSW types overall suggests larger forecast errors or lower skill for MSSWs of the vortex split type,although the differences do not have strong statistical significance for almost all cases.This limitation is likely to at least partly reflect the small sample size of the MSSWs available.     

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.     

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.     

加强业务管理提高测报质量

我局从1999～2003年,测报工作连续4年未出现错情,在此期间共有1个250个班,9个百班无错通过上级业务部门验收.在仪器保管、使用、维护上符合要求,对外报送的各种表、簿都能做好出门合格.     

Addressing the necessity of the registration of the effects of causal mechanics in the example of a simple barotropic model of the atmosphere

Summary Considering the effects of causal mechanics on geophysical problems enables us to explain a number of phenomena, which cannot be explained from conventional positions. This paper shows that the introduction of the force of causality in a simple barotropic hydrodynamic model of weather forecasts results in the outcomes, which, on the one hand, can not be described from the positions of classical hydro-thermodynamics, whilst on the other hand, exist in nature.     

Modeling the evolution of the family of Mediterranean cyclones using the regional model of the atmosphere

Due to the complex orography and the presence of the moisture-saturated air, the Mediterranean region is characterized by the increased baroclinic and convective instability, that leads to the sudden cyclogenesis and the formation of dangerous weather phenomena. The results are given of the investigation of formation mechanisms of Mediterranean cyclones, peculiarities of stages of their evolution and dynamical processes, which occur throughout the atmosphere, using the regional numerical ETA model of the atmosphere by the example of individual cases of the cyclogenesis over the Mediterranean Sea. It is revealed that the cold Arctic air outbreak (the intrusion of the cold Arctic air) to the south of the Western Europe, leading to the formation of the areas of the baroclinic instability and the increased moisture content of the air in the area of the vortex origin, favors the cyclogenesis. The use of the vertical coordinate η in the model enabled to compute more precisely the vertical wind speed, therefore, the influence of the orography on the moisture content and precipitation increase became pronounced. The transformation of the structure of meteorological fields in the course of the development of vortexes is considered. The computation of the helicity is made, and it is shown that this characteristic can be one of the earliest predictors of cyclogenesis.     

流场配置及地形对西南低涡形成的动力作用

本文采用定常二层模式讨论较小地形及高、低层流场配置对西南低涡形成的动力作用。指出了西南低涡的形成是与盆地、河谷以及其上气流分层有关的一种定常态.在上、下为西风分层时期,低层的浅薄暖湿西风有利于西南低涡的形成.在上、下为东、西风分层时期,上层浅薄东风亦有利于西南低涡的形成.小型的凸起山脉对西南低涡的形成没有作用.     

Analysis of the Characteristics of the Low-level Jets in the Middle Reaches of the Yangtze River during the Mei-yu Season

Here, we analyze the characteristics and the formation mechanisms of low-level jets(LLJs) in the middle reaches of the Yangtze River during the 2010 mei-yu season using Wuhan station radiosonde data and the fifth generation of the European Centre for Medium-Range Weather Forecasts(ERA5) reanalysis dataset. Our results show that the vertical structure of LLJs is characterized by a predominance of boundary layer jets(BLJs) concentrated at heights of 900–1200 m.The BLJs occur most frequently at 230...     

On the determination of the height of the Ekman boundary layer

The heighth of the Ekman turbulent boundary layer determined by the momentum flux profile is estimated with the aid of considerations of similarity and an analysis of the dynamic equations. Asymptotic formulae have been obtained showing that, with increasing instability,h increases as ¦¦^1/2 (where is the non-dimensional stratification parameter); with increasing stability, on the other hand,h decreases as ^–1/2. For comparison, a simple estimate of the boundary-layer heighth _u determined by the velocity profile is given. As is shown, in unstable stratification,h _u behaves asymptotically as ¦¦^–1, i.e., in a manner entirely different from that ofh .     

接地降阻剂的PH值的探讨

1引言我国执行接地降阻剂测试的技术标准是全国电力系统起草的:“接地降阻剂暂行技术条件修改稿”。在技术要求中要求接地降阻剂的酸碱值应在7￣12范围内。在实际使用中发现该技术要求对接地降阻剂的酸碱值要求范围并不合理,需要分析和讨论。2接地降阻剂的PH值接地降阻剂的酸碱性对地网的使用寿命至关重要,为了不让接地降阻剂腐蚀接地体或者减弱接地降阻剂对接地体的腐蚀,在接地降阻剂测试的技术要求中,对接地降阻剂的酸碱度有一定的限制。国内各厂家用于生产接地降阻剂的偏弱酸的盐类进行了对镀锌钢材腐蚀的试验,结果是这些镀锌钢材均受到…     

准两年振荡对大气中微量气体分布的影响

NCAR的包含化学、辐射、动力相互作用的两维模式（SOCRATES）移植回国后进行了初步的模拟试验,用以研究某些对环境问题重要的微量气体的化学、辐射、动力传输过程。在不考虑极地平流层云和气溶胶表面非均相化学等情况下,模式积分多年,计算结果稳定,模拟的风场、温度场显示出正常的季节变化,模拟的微量气体分布与卫星实测资料对照,结果也比较一致。为了探讨热带平流层风场的准两年周期振荡（QBO）对平流层微量气体分布的影响,我们做了QBO强迫的数值试验,即在模式中加入QBO强迫,并与不考虑QBO强迫的模拟结果对比。结果表明,QBO与其相关的次级环流所引起动力输送的变化,使平流层微量气体分布发生变化。     

On the forecast of the onset and end of the convective season in the Amazon

Summary ?Some features of the climate system that can be considered predictors of the onset and end of the convective season over the Amazon were identified using one-month lag correlations and field composites. The fields analyzed were sea surface temperature (SST), outgoing long-wave radiation (OLR), vertical velocity and upper tropospheric winds. Warm (cold) anomalies in the SST in the tropical North Atlantic and the Caribbean Sea tend to be associated with delayed (early) onsets. Likewise, there is a tendency towards a delayed (early) end of the convective season with cold (warm) anomalies in these ocean regions. In addition, the SST in the cold tongue region of the equatorial Pacific is negatively, though weakly correlated with the onset date. The signal of this SST is more evident in the case of the end date, which is earlier with respect to its mean date in most of El Ni?o cases. The convective activity intensity itself conditions the onset and the end of the convective season, as it is evidenced by the behavior of the OLR and the vertical velocity fields. The more (less) intense the convective activity over South America during the preceding month, the earlier the onset and the later the end of the convective season on the Amazon region. The prediction of the onset and end dates of the convective season in the Amazon region was explored using a simple multiple regression technique based on the variables that have shown precursor signals with respect to these dates. The correlation coefficient between the predicted and the observed onset date is 0.81, and in the case of the end date, it is 0.76. The skill to predict early, delayed and normal categories was high, since in more than two thirds of the cases the category was successfully predicted, and there were no predictions of categories opposed to those observed. Received July 23, 2001; revised February 22, 2002; accepted April 26, 2002     

阴山山脉对内蒙古中部地区气象要素影响初探

文章选用阴山山脉山北乌拉特后旗、白云、达茂旗、苏尼特左旗、化德,山南杭后旗、包头、呼和浩特、察右前旗、兴和1971—2000年气温、降水量、天气现象等资料进行对比分析,得到阴山山脉对内蒙古自治区中部地区气象要素影响初步结论。