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261.
Regional frequency analysis of extreme precipitation and its spatio-temporal characteristics in the Huai River Basin, China 总被引:1,自引:1,他引:0
With the increasing exposure of populations and economy to natural hazards, the spatio-temporal characteristics of extreme rainfall remain a key subject of study. Based on annual maximum rainfall (AM) and peaks over threshold rainfall series at 30 meteorological stations during 1960–2011 in the Huai River Basin (HRB), spatio-temporal characteristics of extreme rainfall are analyzed through regional frequency analysis method using L-moments. The accuracy and uncertainty analysis of quantile estimations are also carried out, and the regional and at-site frequency analyses are compared. Results indicate the following: (1) During 1960–2011, AM precipitation at 20 stations in the HRB shows an increasing trend, while at the other 10 stations, it shows a decreasing trend. And both the increased and decreased trends are not significant. (2) The HRB can be categorized into three homogeneous regions via cluster analysis. For both at-site and regional frequency analyses, the root mean square error values increase with the increase in return periods. The estimations are reliable enough for the return periods of less than 100 years. The quantile estimates of large return period from regional frequency analysis are more accurate and have smaller uncertainty than those from at-site frequency analysis. (3) Extreme precipitation in the HRB concentrates in the upstream of the Huai River and YiShuSi water system in the east of the HRB. Generally, the area with extreme precipitation, especially the upper reaches of the Huai River and Yimeng Mountain areas, also has large standard variations of extreme precipitation, which will increase the risk of natural hazards. 相似文献
262.
利用美国国家和海洋大气管理局(NOAA)的大气温度数据, 分析陆地地震和海洋地震震前震中上空的大气温度变化, 研究其作为地震短临前兆的可能性.地震样本包括2014年2月12日于田Ms7.3地震、2008年5月12日汶川Ms8.0地震、2011年3月11日日本Ms9.0地震、2014年4月1日智利Ms8.1海洋地震、2013年3月27日台湾南投县Ms6.1地震和2014年5月30日云南盈江Ms6.1地震.结果表明: (1)震前, 震中位置300~1 000 hPa大气温度有较为一致的变化趋势; (2)200 hPa与400 hPa处(根据不同地点可选择其他, 诸如350 hPa、300 hPa等高度数据)温度折线图在震前趋近或者相交, 出现类似蝴蝶翅膀的"蝴蝶形"特殊曲线形状; (3)200 hPa与400 hPa温度差等值线图在(震前数月、数周或数天不等)震中附近区域的数值减小, 温度差等值线图的塌陷最低点对应震中位置.以上规律有望应用于地震短临预测的时间与震中的确定. 相似文献
263.
264.
基于2017年流动人口动态监测调查数据,分析了中国城市流动人口心理融入的区域差异和影响因素。结果表明:① 流动人口心理融入处于较高水平;② 流动人口心理融入区域差异显著。东南沿海及少数西部城市心理融入低于全国平均水平,东北、山东和川渝等地区心理融入高于全国平均水平;③ 流动人口心理融入存在空间集聚效应。除川渝地区外,热点区集中于北方地区,冷点区集中于东南地区。④ 拥有房产、雇主身份和较高受教育水平加快流动人口的心理融入;工资收入的增加不利于心理融入,这与相对剥夺感有关;参与“新农合”对流动人口心理融入具有约束效应;暂住证/居住证及基本公共服务均等化是实现心理融入的重要途径。城市经济快速发展利于流动人口心理融入。跨省流动存在抑制作用,经济发展水平、家庭规模和本地居留时间的作用不显著。 相似文献
265.
266.
高中地理课程改革要求重视学科大概念。UbD理论提出的逆向教学设计是在教学中落实学科大概念的重要途径。UbD理论指导下的逆向教学设计以学科大概念为核心、以学习结果为起点、评价优先,能够在教学中凸显学科大概念的价值和作用,符合新课程改革的理念。本文以人教版高中地理选择性必修3中的“中国的能源安全”为例进行逆向教学设计,提出在地理课堂中应用UbD理论进行逆向教学设计的策略。 相似文献
267.
Use of the L2C signal for inversions of GPS radio occultation data in the neutral atmosphere 总被引:1,自引:0,他引:1
S. V. Sokolovskiy W. S. Schreiner Z. Zeng D. C. Hunt Y.-H. Kuo T. K. Meehan T. W. Stecheson A. J. Mannucci C. O. Ao 《GPS Solutions》2014,18(3):405-416
Results from processing FORMOSAT-3/COSMIC radio occultations (RO) with the new GPS L2C signal acquired both in phase locked loop (PLL) and open loop (OL) modes are presented. Analysis of L2P, L2C, and L1CA signals acquired in PLL mode shows that in the presence of strong ionospheric scintillation not only L2P tracking, but also L1CA tracking often fails, while L2C tracking is most stable. The use of L2C improves current RO processing in the neutral atmosphere mainly by increasing the number of processed occultations (due to significant reduction in the number of L2 tracking failures) and marginally by a reduction in noise in statistics. The latter is due to the combination of reduced L2C noise (compared to L2P) and increased L1CA noise in those occultations where L2P would have failed. This result suggests application of OL tracking for L1CA and L2C signals throughout an entire occultation to optimally acquire RO data. Two methods of concurrent processing of L1CA and L2C RO signals are considered. Based on testing of individual occultations, these methods allow: (1) reduction in uncertainty of bending angles retrieved by wave optics in the lower troposphere and (2) reduction in small-scale residual errors of the ionospheric correction in the stratosphere. 相似文献
268.
Rafael Rosolem Hoshin V. Gupta W. James Shuttleworth Luis Gustavo Gonçalves de Gonçalves Xubin Zeng 《水文研究》2013,27(14):2075-2097
In climate models, the land–atmosphere interactions are described numerically by land surface parameterization (LSP) schemes. The continuing improvement in realism in these schemes comes at the expense of the need to specify a large number of parameters that are either directly measured or estimated. Also, an emerging problem is whether the relationships used in LSPs are universal and globally applicable. One plausible approach to evaluate this is to first minimize uncertainty in model parameters by calibration. In this paper, we conduct a comprehensive analysis of some model diagnostics using a slightly modified version of the Simple Biosphere 3 model for a variety of biomes located mainly in the Amazon. First, the degree of influence of each individual parameter in simulating surface fluxes is identified. Next, we estimate parameters using a multi‐operator genetic algorithm applied in a multi‐objective context and evaluate simulations of energy and carbon fluxes against observations. Compared with the default parameter sets, these parameter estimates improve the partitioning of energy fluxes in forest and cropland sites and provide better simulations of daytime increases in assimilation of net carbon during the dry season at forest sites. Finally, a detailed assessment of the parameter estimation problem was performed by accounting for the decomposition of the mean squared error to the total model uncertainty. Analysis of the total prediction uncertainty reveals that the parameter adjustments significantly improve reproduction of the mean and variability of the flux time series at all sites and generally remove seasonality of the errors but do not improve dynamical properties. Our results demonstrate that error decomposition provides a meaningful and intuitive way to understand differences in model performance. To make further advancements in the knowledge of these models, we encourage the LSP community to adopt similar approaches in the future. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
269.
曾维达 《成都信息工程学院学报》1993,(1)
气象部门研制的业务系统应用软件,取得了明显的社会效益及一定的经济效益。但由于注意标准化系统化不够,难以推广移植。而九十年代因更多信息交换的需要,不仅要注意软件开发的工程化,还应注意系统总体设计。在八五课题实施研究的时机,应大力推行系统总体设计和软件开发的工程化。 相似文献
270.