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梅雨锋的典型结构、多样性和多尺度特征 总被引：3，自引：1，他引：3
在天气尺度梅雨锋的天气学定义基础上,利用GMS-5静止卫星红外云图、常规气象探空资料、NCEP再分析与最终分析资料对2002年长江流域典型梅雨期6月26—28日和二度梅期间7月23日、1998年5月梅雨与7月二度梅共4个梅雨锋个例进行了分析与比较,归纳了梅雨锋结构多样性;并着重对典型梅雨期的梅雨锋发展过程、水平以及垂直结构进行了多种物理量场(包括风场、温度场、急流、锋区、假相当位温、散度、垂直速度、静力稳定度等)的综合分析。结果表明,不同的个例,不同的地区和时期,一次梅雨过程的不同阶段,梅雨锋的结构和性质都有可能不同,它可以从比较接近极锋的性质过渡到接近赤道锋的性质。在水平结构上梅雨锋是在高、低纬度不同尺度的环流系统共同作用下形成的,从而造成了梅雨锋结构具有丰富的多样性。对典型梅雨锋结构进行综合分析表明梅雨锋对流层中下层锋面由强假相当位温水平梯度形成;梅雨锋南侧为暖湿气团、北侧为变性气团;梅雨锋南面为西南季风、北面为偏东气流;梅雨锋的上升运动和强降水主要发生在梅雨锋的前沿;梅雨锋上方对流层上半部存在与副热带高空急流相配合的高空副热带锋;对流层上部的高空热带东风与副热带高空西风急流构成了梅雨锋降水的高空辐散流场。根据典型期梅雨锋以及二度梅倾斜型梅雨锋的对流层上、中、下水平环流特征,给出了梅雨锋的多尺度概念模型,主要包括中低纬度系统相互作用、对流层高层的行星尺度的环流系统副热带高空西风急流、高空热带东风急流与南亚高压、对流层中层的副热带高压与北方的短波槽以及对流层低层的行星尺度季风和切变线。 相似文献
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Summary The Oklahoma Atmospheric Surface-layer Instrumentation System (OASIS) is a recently-developed observational system that collects,
archives, and quality controls atmospheric, surface, and soil data in real-time from 90 stations across Oklahoma. Ten of the
90 sites, termed “super sites”, are equipped with additional sonic anemometry and four-component net radiometers to provide
complete observations of the surface energy balance. Oklahoma Mesonet and OASIS data are used in this study to validate the
sensitivity and accuracy of a land-surface scheme within a numerical prediction model.
The Advanced Regional Prediction System (ARPS) is a three-dimensional, nonhydrostatic mesoscale model developed by the Center
for Analysis and Prediction of Storms (CAPS) at the University of Oklahoma. The land-surface model (LSM) used within ARPS
is the Interactions Soil Biosphere Atmosphere (ISBA) scheme. Mesonet and OASIS data collected from the super site located
in Norman, Oklahoma, are used as verification for the ISBA.
Research presented in this study outlines the challenges in developing, maintaining, and using in-situ data for model validation.
Such problems as instrument error, surface heterogeneity, and non-closure of the surface energy budget limit data accuracy.
Preliminary results of model validation focus on the sensitivity of the soil physics within the ISBA scheme. Model sensitivity
to vegetation cover, surface roughness, and soil type are investigated. Furthermore, several recent improvements to ISBA are
evaluated and compared to observations. This study concludes that the sensitivity of the ISBA to a priori soil and vegetation
type is detrimental for this scheme to be used in a mesoscale model without improved treatment of surface heterogeneity.
Received November 18, 2001 Revised December 28, 2001 相似文献
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E. Grün Z. Sternovsky M. Horanyi V. Hoxie S. Robertson J. Xi S. Auer M. Landgraf F. Postberg M.C. Price R. Srama N.A. Starkey J.K. Hillier I.A. Franchi P. Tsou A. Westphal Z. Gainsforth 《Planetary and Space Science》2012,60(1):261-273
The Stardust mission returned two types of unprecedented extraterrestrial samples: the first samples of material from a known solar system body beyond the moon, the comet 81P/Wild2, and the first samples of contemporary interstellar dust. Both sets of samples were captured in aerogel and aluminum foil collectors and returned to Earth in January 2006. While the analysis of particles from comet Wild 2 yielded exciting new results, the search for and analysis of collected interstellar particles is more demanding and is ongoing.Novel dust instrumentation will tremendously improve future dust collection in interplanetary space: an Active Cosmic Dust Collector is a combination of an in-situ dust trajectory sensor (DTS) together with a dust collector consisting of aerogel and/or other collector materials, e.g. such as those used by the Stardust mission. Dust particles’ trajectories are determined by the measurement of induced electrical signals when charged particles fly through a position sensitive electrode system. The recorded waveforms enable the reconstruction of the velocity vector with high precision.The DTS described here was subject to performance tests at the Heidelberg dust accelerator at the same time as the recording of impact signals from potential collector materials. The tests with dust particles in the speed range from 3 to 40 km/s demonstrate that trajectories can be measured with accuracies of ～1° in direction and ～1% in speed. The sensitivity of the DTS electronics is of the order of 10?16 C and thus the trajectory of cosmic dust particles as small as 0.4 μm size can be measured. The impact position on the collector can be determined with better than 1 mm precision, which will ease immensely the task of locating sub-micron-sized particles on the collector. Statistically significant numbers of trajectories of interplanetary and interstellar dust particles can thus be collected in interplanetary space and their compositions correlated with their trajectories. 相似文献
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Typical Structure, Variety, and Multi-Scale Characteristics of Meiyu Front 总被引：1，自引：0，他引：1 
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下载免费PDF全文 Meiyu front plays an important role in summer rainfall in central China. Based on the GMS-5 satellite images, NCEP reanalyses （2.5°×2.5°） and final analyses （1°×1°） data, and meteorological conventional sounding observations, the horizontal and vertical structures of the Meiyu front were summarized using multiple diagnostic variables, including winds, temperature, jet stream, front, pseduo-equivalent potential temperature, divergence, vertical motion, static instability, etc. In this paper, four cases were selected and analyzed, two of which are in 26-28 June and 23 July 2002 during the Experiment on Heavy Rain in the Meiyu period in the lower reaches of the Yangtze River, and the others are in May and July 1998. The two cases in July 1998 and July 2002 are the secondary Meiyu front cases. The results show that the structures and characteristics of the Meiyu front are different for various cases, or at various places and time, or at various stages of one case, and the frontal characteristics can be converted from the polar front to the equatorial front. Because of the interaction of the different scale circulations in the high and low latitudes, the horizontal structure of the Meiyu front has various forms.
The results in this paper also show that the typical Meiyu front consists of a narrow band with a high gradient of potential equivalent temperature below 500 hPa, south of which is warm and moist air mass, and north of which is the transformed air mass from the midlatitude ocean or polar continent. Below the mid troposphere, south of the front blows southwesterlies, while north blows easterlies. The ascending motion and precipitation usually occur ahead of the Meiyu front. In the upper troposphere, the subtropical front is above the Meiyu front, but two fronts are separated. In addition, the upper westerly jet stream and the easterlies to the south of the Meiyu front result in the upper divergent flow field.
The multi-scale characteristics of the horizontal structure of the Meiyu front can 相似文献
The results in this paper also show that the typical Meiyu front consists of a narrow band with a high gradient of potential equivalent temperature below 500 hPa, south of which is warm and moist air mass, and north of which is the transformed air mass from the midlatitude ocean or polar continent. Below the mid troposphere, south of the front blows southwesterlies, while north blows easterlies. The ascending motion and precipitation usually occur ahead of the Meiyu front. In the upper troposphere, the subtropical front is above the Meiyu front, but two fronts are separated. In addition, the upper westerly jet stream and the easterlies to the south of the Meiyu front result in the upper divergent flow field.
The multi-scale characteristics of the horizontal structure of the Meiyu front can 相似文献
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