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61.
局地强风暴云团与中尺度锋面波动 总被引:6,自引:0,他引:6
本文分析了1982—1988年2—5月份的41例与中尺度锋面波动相关联的局地强风暴云团的活动和演变特征,给出了其强盛期天气系统配置模式及其在天气尺度云系演变中的表现型式,最后对其移动做了一般性讨论。 相似文献
62.
用二维非静力完全弹性的中-γ尺度数值模式模拟了移动性热岛的大气边界层特征。试验中,热岛移速取为4m·s^-1,热岛强度取△θg=60K和30K两种。△θg=60K时,在热岛后方出现了强烈的垂直运动并形成了水平尺度为3-5km的局地环流,最大上升速度100cm·s^-1,出现在低层300-400m高度;△θg=30K时,移动热岛的边界效应比前大为减弱,且不再出现闭合的局地环流。 相似文献
63.
64.
岳荣先 《南京气象学院学报》1995,18(4):511-517
从模型微小扰动的角度研究数据对回归估计精度的局部影响。首先提出刻划这种影响的4个统计量,并求出它们在3种不同扰动方式下的最大局部变化方向,其最大绝对分量对应于强影响点。最后给出一个数值例子来说明这种强影响点的诊断。 相似文献
65.
P. Fabbri 《Mathematical Geology》2001,33(6):745-760
In the geothermal Euganean area (Veneto region, NE Italy) water temperatures range from 60 to 86°C. The aquifer considered is rocky and the production wells in this study have a depth ranging from 300 to 500 m. For exploitation purposes, it is important to identify zones with a high probability that the temperature is more than 80°C and zones with a high probability that the temperature is less than 70°C. First, variographic analysis was conducted from 186 temperature data of thermal ground waters. This analysis gave results that are consistent with the main regional tectonic structure, the NW-SE trending Schio-Vicenza fault system. Then indicator variograms of the second, fifth, and eighth decile were compared to identify the spatial continuity at different thresholds. The unacceptability of a multigaussian hypothesis of the random function and the necessity to know the cumulative distribution function in any location, suggested the use of a nonparametric geostatistical procedure such as indicator kriging. Thus, indicator variograms at the cutoffs of 65, 70, 73, 75, 78, 80, 82, and 84°C were analyzed, fitted, and used during the indicator kriging procedure. Finally, probability maps were derived from postprocessing indicator kriging results. These maps identified scarcely exploited areas with a high probability of the temperature being higher than 80°C, between 70 and 80°C and areas with high probability of the temperature being below 70°C. 相似文献
66.
局部重磁场源全方位成像理论概要(续) 总被引:4,自引:4,他引:0
作者近年来首创了"复杂条件下局部重磁场源全方位成像"理论体系。在本文中,概要阐述该理论体系中下延有限二度体复重磁场级数正演通式、复场模值全方位延拓和全方位反演等。 相似文献
67.
We statistically analyze the tropical typhoon forming in the South China Sea and use TC (Tropical
Cyclone) for short in the following) by typhoon yearbook. The typhoon quantity is very different in different
months and years. TC appears in all months except March, and the most TC quantity in a year is 11, the least is 1
and 6.2 on average. The most TC quantity in a month is 5 and the least is 0. TC lands most in August and no TC
lands on Chinese continent from December to the following April. The primary landing area is between Shantou
and Hainan Island. The sustaining period of TC is usually between 4 days to 7days, and the longest is 19 days.
Only 15% of the TC forming in the South China Sea can intensify to typhoon, and they all form in the ocean area
deeper than 150m. The South China Sea is the ocean area over which the TC occurs frequently. 相似文献
68.
Local knowledge has played an active role in the lives of rural communities in virtually every part of the world. In Jamaica, traditional cropping systems based on local informal knowledge have been practiced since the days of slavery and play a vital role in meeting food security. Yet, some negative attitudes remain about the legitimacy and relevance of small-scale farmers' local and traditional knowledge. This paper discusses some conceptual and empirical issues related to the application of local knowledge among small-scale food farmers in central Jamaica. The paper argues that contextually speaking, local and traditional knowledge is valuable, adaptable and necessary in coping with risk and uncertainty in a changing world, while cautioning against a misguided notion of traditional knowledge as a panacea to all the ills of local agriculture. 相似文献
69.
70.
Bellie Sivakumar 《地球表面变化过程与地形》2007,32(7):969-979
Whether or not river flow exhibits nonlinear determinism remains an unresolved question. While studies on the use of nonlinear deterministic methods for modeling and prediction of river flow series are on the rise and the outcomes are encouraging, suspicions and criticisms of such studies continue to exist as well. An important reason for this situation is that the correlation dimension method, used as a nonlinear determinism identification tool in most of those studies, may possess certain limitations when applied to real river flow series, which are always finite and often short and also contaminated with noise (e.g. measurement error). In view of this, the present study addresses the issue of nonlinear determinism in river flow series using prediction as a possible indicator. This is done by (1) reviewing studies that have employed nonlinear deterministic methods (coupling phase‐space reconstruction and local approximation techniques) for river flow predictions and (2) identifying nonlinear determinism (or linear stochasticity) based on the level of prediction accuracy in general, and on the prediction accuracy against the phase‐space reconstruction parameters in particular (termed as the ‘inverse approach’). The results not only provide possible indications to the presence of nonlinear determinism in the river flow series studied, but also support, both qualitatively and quantitatively, the low correlation dimensions reported for such. Therefore, nonlinear deterministic methods are a viable complement to linear stochastic ones for studying river flow dynamics, if sufficient caution is exercised in their applications and in interpreting the outcomes. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献