Synoptic circulation and stream discharge in the Great Lakes basin, USA     

R. V. Rohli  A. J. Vega  M. R. Binkley  S. D. Britton  H. E. Heckman  J. M. Jenkins  Y. Ono  D. E. Sheeler 《Applied geography (Sevenoaks, England)》2001,21(4)

Impacts on water resources caused by human activity, natural climate variation and long-term climate change are unclear in the US Great Lakes region. Improved understanding of the impact of atmospheric circulation on stream discharge variability into the Lakes is thus important. In this analysis, monthly surface and mid-tropospheric circulation patterns suggest that surface pressure variations over Missouri and Illinois are most strongly correlated to discharge. The mid-tropospheric patterns most directly related to discharge place the Great Lakes in a trough-to-ridge flow pattern. The analysis confirms that at this scale, lee shore advection resulting in ‘lake-effect’ precipitation is not very important to regional discharge, and neither are variations in the Pacific–North American teleconnection.  相似文献   

Partitioning of heavy metals on soil samples from column tests   总被引：3，自引：0，他引：3  

R. N. Yong  W. Z. W. Yaacob  S. P. Bentley  C. Harris  B. K. Tan   《Engineering Geology》2001,60(1-4):307-322

In this study, column tests were used to determine the retention capability of three types of estuarine alluvia collected adjacent to landfill sites in South Wales. Selective sequential extraction (SSE) was used to study the retention mechanisms of heavy metals in the soil columns obtained from leaching experiments. Acid digestion was later used to check the validity of the SSE results. Breakthrough curves show good retention of heavy metal ions (Pb, Cu, and Zn) by all soils, where almost 99% of heavy metals were retained with the C_e/C_o values in the order of 10⁻³. The retention strength of these soils was observed to be constant up to five pore volumes (PV). This corresponds with the pH of the effluents and pore water of soil slices, which also show good buffering capacity against very acidic leachate up to 5PV. The heavy metal extraction profiles from SSE show very similar trends with the retention profiles from the leaching experiments, where heavy metals were retained mainly at the top part where the leachate entered the column. SSE indicates qualitatively that heavy metals precipitated with carbonates and amorphous materials (oxides/hydroxides) are higher than heavy metal retention via exchangeable mechanisms. The mass balance calculation gives range of deviation of 1–16% of the total soil extraction. The distribution of the heavy metals with various soil constituents are ranked in the following order: Carbonates>Amorphous oxides hydroxides>Organic matter>Exchangeable phases.  相似文献   

有限区域高分辨率模式的改进,发展及试验     

陈玉春  张华 《高原气象》1996,15(1):11-20

对复杂地形条件下嵌套细网和数据模式进行了改进和发展，使之成为水平格距为５０ｋｍ，垂直分层为１１层的高分辨率模式。同时对其物理过程如积云对流参数化、边界层物理等也进行了改进，并将该模式程序优化为能在计算机工作站和微机上进行业务运行的数值预报系统。  相似文献   

人工触发闪电与降雨倾泻   总被引：1，自引：3，他引：1  

张义军  言穆弘 《高原气象》1995,14(4):406-414

根据人工触发阀电后雨量猛增的观测事实，利用一个简单的静电模式计算了闪道附近雨滴的重力碰并增长，结果指出，闪电后降雨猛增必须满足一定的条件，除了要求较高的离子浓度（〉１０＾１４／ｍ＾３）外，还取决于闪电所引起的电场变化和闪电被触发后闪道附近环境电场强度的特性。  相似文献   

双线偏振雷达的降水估测Ⅰ. 排序配对逼近法   总被引：6，自引：5，他引：1  

楚荣忠  贾伟 《高原气象》1999,18(1)

提出使用新的途径──排序配对逼近法得出的双线偏振雷达降水估测ＺＲ关系参数因子比线性拟合法具有更好的代表性,且能体现提高区域降水估测精度,也能根据实际情形采用其它的误差类型作为获取及衡量参数的标准。对指数函数形式的ＺＲ关系来说,其参数因子Ａ０,ＡＨ及ＡＤＲ分别为０．０１６８４,０．０９６和－０．４１６５。该方法可以推广应用到多个变元及参数因子的复杂函数中。  相似文献   

东海近海热带气旋及天气数值预报系统     

雷小途  端义宏 《成都信息工程学院学报》1999,(2):56

以ＭＭ４模式为框架,研制并建立了东海近海热带气旋及天气数值预报系统,将对热带气旋的预报和一般天气的预报统一在一个模式中,并实现了业务自动化控制,自１９９４年台风季节起投入了业务试验和准业务的运行。结果表明：该系统对东海近海热带气旋路径、风场、降水及江淮梅雨降水具有较好的预报能力  相似文献   

SVD迭代模型在夏季降水预测中的应用   总被引：7，自引：0，他引：7  

张永领  吴胜安  丁裕国  何桐  高全洲 《气象学报》2006,64(1):121-128

文中设计了一种基于SVD迭代的短期气候预测模型,通过选择适当的影响因子,建立与预测对象之间的联系,从而实现对气象场序列的预测。分别对华北16个测站和长江中下游地区30个测站1991—2000年近10a夏季(6—8月)降水做预测试验,平均均方误差分别为0.352和0.312,平均符号相关系数分别为0.575和0.623。此研究表明,基于SVD迭代的气候预测模型是一种非常有效的短期气候预测途径,具有很强的应用价值。  相似文献   

Spatiotemporal analysis of precipitation trends in the Yangtze River catchment   总被引：2，自引：2，他引：2  

Stefan Becker  Marco Gemmer  Tong Jiang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2006,20(6):435-444

Precipitation trends in the Yangtze River catchment (PR China) have been analyzed for the past 50 years by applying the Mann-Kendall trend test and geospatial analyses. Monthly precipitation trends of 36 stations have been calculated. Significant positive trends at many stations can be observed for the summer months, which naturally show precipitation maxima. They were preceded and/or followed by negative trends. This observation points towards a concentration of summer precipitation within a shorter period of time. The analysis of a second data set on a gridded basis with 0.5° resolution reveals trends with distinct spatial patterns. The combination of classic trend tests and spatially interpolated precipitation data sets allows the spatiotemporal visualization of detected trends. Months with positive trends emphasize the aggravation of severe situation in a region, which is particularly prone to flood disasters during summer. Reasons for the observed trends were found in variations in the meridional wind pattern at the 850 hPa level, which account for an increased transport of warm moist air to the Yangtze River catchment during the summer months.  相似文献   

近55年中国大陆地区降水突变的区域特征   总被引：2，自引：0，他引：2  

向辽元  陈星  黎翠红  郑京华 《湖北气象》2007,26(2):149-153

利用中国大陆1951～2003年160站较为完整的降水观测资料,采用Mann-Kendall检验法和小波分析方法,确定了中国大陆不同区域降水突变事件的大致时间,研究揭示了近55年中国大陆降水突变事件变化的区域特征。得出如下结论:(1)近55年来,中国大陆年平均降水量正在逐步减少。华北地区、四川盆地和东北地区年降水量减少明显。年降水量增加的区域位于长江中下游及其以南地区,另外,西北部分地区和青藏高原南部略有增加。(2)中南地区和青藏云地区年降水在20世纪90年代中后期出现突变,华北地区降水突变出现在20世纪70年代中期,东北地区突变出现在20世纪60年代中期,华南地区降水在20世纪70年代初期出现突变。  相似文献   

A radar-based verification of precipitation forecast for local convective storms     

Daniela Rezacova  Zbynek Sokol  Petr Pesice 《Atmospheric Research》2007,83(2-4):211-224

Local flash flood storms with a rapid hydrological response are a real challenge for quantitative precipitation forecasting (QPF). It is relevant to assess space domains, to which the QPF approaches are applicable. In this paper an attempt is made to evaluate the forecasting capability of a high-resolution numerical weather prediction (NWP) model by means of area-related QPF verification. The results presented concern two local convective events, which occurred in the Czech Republic (CR) on 13 and 15 July 2002 and caused local flash floods. We used the LM COSMO model (Lokall Model of the COSMO consortium) adapted to the horizontal resolution of 2.8 km over a model domain covering the CR. The 18 h forecast of convective precipitation was verified by using radar rainfall totals adjusted to the measured rain gauge data. The grid point-related root mean square error (RMSE) value was calculated over a square around the grid point under the assumption that rainfall values were randomly distributed within the square. The forecast accuracy was characterized by the mean RMSE over the whole verification domain. We attempt to show a dependence of both the RMSE field and the mean RMSE on the square size. The importance of a suitable merger between the radar and rain gauge datasets is demonstrated by a comparison between the verification results obtained with and without the gauge adjustment. The application of verification procedure demonstrates uncertainties in the precipitation forecasts. The model was integrated with initial conditions shifted by 0.5° distances. The four verifications, corresponding to the shifts in the four directions, show differences in the resulting QPF, which depend on the size of verification area and on the direction of the shift.  相似文献