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1.
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. 相似文献
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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. 相似文献
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Phase Two of the Integrative Monsoon Frontal Rainfall Experiment (IMFRE-II) over the Middle and Lower Reaches of the Yangtze River in 2020 总被引:1,自引:0,他引:1
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. 相似文献
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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). 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献
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Masakazu TAGUCHI 《大气科学进展》2020,37(3):250-258
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... 相似文献
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南京三千公尺高空之风向与天气之预测 总被引:1,自引:0,他引:1
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。 相似文献
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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. 相似文献
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Infrared device for simultaneous measurement of fluctuations of atmospheric carbon dioxide and water vapor 总被引:3,自引:0,他引:3
An infrared device designed to measure simultaneous fluctuations of atmospheric CO2 and water vapor concentrations is described. The measuring frequency is 30 Hz. The sensing path length is 20 cm. It is compatible with the path length of the standard type of a sonic anemometer. The noise level of the device is equivalent to fluctuations of about 0.8 ppm peak-to-peak for CO2 and 0.02 g kg-1 peak-to-peak for water vapor. Field tests have showed that the device is suitable for simultaneous measurement of turbulent fluxes of CO2 and water vapor in conjunction with a sonic anemometer. 相似文献
13.
《Agricultural Meteorology》1976,16(1):71-84
A new device for continuous computing and recording of the energy balance terms is described with some of its principal advantages and characteristics. Hourly and daily printed mean results are compared with those of a sensible weighing lysimeter. Satisfactory performances were obtained during the two last past years, so it is actually used on any natural surfaces, instead of weighing lysimeter, with its simple package which only needs power. 相似文献
14.
Transport safety is a major goal in the European Union. Low visibility conditions, especially due to fog, increase the risk of major accidents (chain collision). Innovative products have been developed by the automotive industry, including equipment manufacturers, to increase the level of safety of car passengers and drivers. Testing of these products requires the simulation or artificial reproduction of low visibility (fog) conditions with good stability and reproducibility characteristics. We report on the results of the European Union funded “FOG” project to improve road transport safety through fog production in an experimental test chamber located at the Clermont-Ferrand laboratory for research on road safety and visibility. The project developed a prototype of a small-scale climatic chamber, an improved fog production spraying device, a laser-based visibility measurement device, a reduced scale transmissometer, and a combined indoor climate-fog production simulation software. The ability of the fog chamber to test for driver reaction was also investigated. Recent developments include a device able to produce stable visibility levels and homogeneous fog, representative of various types of natural water droplet distribution. The fog characteristics were determined and compared to natural fog. Results are presented for a selection of conditions including stabilized visibility levels for dense fog and two kinds of droplet distributions. 相似文献
15.
针对天水早春气温波动大,寒潮、大风天气多,低温冷害重而育苗成活率低的气候背景,1996~1998年对烤烟育苗期间,进行适宜气象条件及最佳育苗设施手对比试验研究,得出当地烤烟幼苗健壮生长的最适环境气象条件,同时,也得出了当地烤烟育苗的最佳设计是双膜纸钵大畦与弓棚大畦,以双膜钵大畦最佳。 相似文献
16.
A ground-based rime-meter developed by Hydro-Quebec was evaluated in 1992 in the icing tunnel at Université du Québec à Chicoutimi (UQAC) and this instrument is presently used in a network of stations monitoring rime and other iced precipitations in the province of Quebec (Canada). The rimemeter uses, as a sensing element, the probe of the Rosemount icing detector model 871A regulated by an improved programmable controller. The purpose of the evaluation was to characterize the frequency response of the rime-meter mounted with various probes in order to determine their dynamic sensitivity and accuracy under a variety of operating and icing conditions apt to occur in field. The tunnel investigation showed the high sensitivity of the probe to meter ice accumulation. Therefore, it appears feasible under dry conditions, with appropriate calibration, to use this ice sensor as a device for determining the liquid water content. However, its operation in freezing rain near 0°C requires further investigation in the laboratory and in the field. 相似文献
17.
针对组合型电涌保护器(SPD)中主要防雷元件之间的能量配合问题,依据IEC 62305-4与GB 50343—2010的规定要求,通过对气体放电管(GDT)、金属氧化物压敏电阻(MOV)、瞬态抑制二极管(TVS)进行理论概述,再对这3种常见的防雷元器件进行并联组合后,分别进行多次冲击实验,发现不同的防雷元件的合理并联配合使用对于提高SPD整体的响应速度,缩短动作过程时间,提高SPD的通流容量与限压水平具有明显的效果.实验结论对于组合型SPD的设计具有一定的实际参考价值. 相似文献
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人为引发的下沉气流可以抑制对流云的发展,这一现象已在试验中得到验证。用“人工下沉气流法”实施人工消云试验时,需在云顶大剂量的播撒粉剂催化剂。北京市人工影响天气办公室研制了能完成此类大剂量播撤任务的设备,并通过外场飞行试验对设备进行检验和改进。这是国内人工影响天气领域首个采用空投播撒法的粉剂催化剂播撤设备;可减少催化剂对飞机和播撤设备的污染。分析发现,新设备能够满足人工消云作业中播撒大剂量粉剂催化剂的需要。该设备在北京奥运会、残奥会开闭幕式当日的消云试验作业中投入使用,共实施消云飞行作业9架次,累计利用新设备播撒吸湿性粉剂催化剂34吨。 相似文献