承压井水位对含水层潮汐应力响应是否满足不排水条件的检验

以Hsieh模型为基础,提出了利用地震前后承压井水位潮汐分波的振幅及初始相位变化与否作为判断依据,检验井水位对含水层潮汐应力响应是否满足不排水条件的简便方法.将该判别方法用于分析会理川-06井和川-18片水位观测数据,利用Baytap-G潮汐分析方法分别计算出3次选定地震前后两井水位各分波(M2和O1)振幅和相位值.结...     

季风湿润区冬季水汽收支年际及年代际变化特征

采用1958—2007年NCEP/NCAR再分析资料和我国160站降水资料,对东亚大陆季风湿润区冬季的水汽收支变化与大气环流和我国降水异常特征的关系进行研究。结果表明:冬季水汽收支时间序列表现出明显的长期气候变化趋势。挑选的水汽收支高、低值年不仅能够指示季风湿润区经向风的异常变化,还能够指示东亚冬季风的强弱和降水的异常变化。高值年,蒙古冷高压和阿留申低压偏弱,对流层低层为异常偏南风,整层为异常逆时针环流,30°N以南的辐合和上升运动强,大气水分收入增多,降水增加;低值年则相反。差值合成的异常降水量中心值可达40 mm以上,差值合成的水汽异常输入主要集中在600~900 hPa。合成的经向水汽收支占净收支变化的91.3%,纬向上相差较小。季风湿润区南、北区域的水汽收支及降水的差异明显,纬向的收入支出对此差异贡献较大。水汽收支的年代际特征,不仅能够指示水汽输送的强弱及从海洋输入水汽的多少,还能够指示季风湿润区降水的变化,且差值合成的异常降水量最大可达30 mm以上。     

南宁市空气质量状况分析

总结分析2002—2009年南宁市逐日及月平均、季平均、年平均空气质量状况。2002—2009年,南宁市空气质量优良率为96．8％,首要空气污染物主要为可吸入颗粒物和二氧化硫,而又以可吸入颗粒物居多。在2002年至2009年,西乡塘区是南宁市空气质量最好的城区,江南区是南宁市空气质量最差的城区。2005年以后,南宁市全...     

贺州自动站替换人工观测对资料连续性影响分析

对贺州站2004～2005年自动站与人工站平行观测的气温资料进行资料差异性分析,对气温月、日平均值及其平均差值进行了显著性检验,结果表明自动站气温和人工站气温数据差异性不显著,资料的连续性很好,但仍存在一定的系统误差.如能采用适当的方法进行订正,将极大地提高资料的可用性.     

激光雷达在大气混合层探测中的应用

利用香港的激光雷达资料,结合当地的探空资料和天气资料,分析激光雷达在观测大气混合层厚度及其特征。     

Logistic regression model for predicting the failure probability of a landslide dam

Landslides may obstruct river flow and result in landslide dams; they occur in many regions of the world. The formation and disappearance of natural lakes involve a complex earth–surface process. According to the lessons learned from many historical cases, landslide dams usually break down rapidly soon after the formation of the lake. Regarding hazard mitigation, prompt evaluation of the stability of the landslide dam is crucial. Based on a Japanese dataset, this study utilized the logistic regression method and the jack-knife technique to identify the important geomorphic variables, including peak flow (or catchment area), dam height, width and length in sequence, affecting the stability of landslide dams. The resulting high overall prediction power demonstrates the robustness of the proposed logistic regression models. Accordingly, the failure probability of a landslide dam can also be evaluated based on this approach. Ten landslide dams (formed after the 1999 Chi-Chi Earthquake, the 2008 Wenchuan Earthquake and 2009 Typhoon Morakot) with complete dam geometry records were adopted as examples of evaluating the failure probability. The stable Tsao-Ling landslide dam, which was induced by the Chi-Chi earthquake, has a failure probability of 27.68% using a model incorporating the catchment area and dam geometry. On the contrary, the Tangjiashan landslide dam, which was artificially breached soon after its formation during the Wenchuan earthquake, has a failure probability as high as 99.54%. Typhoon Morakot induced the Siaolin landslide dam, which was breached within one hour after its formation and has a failure probability of 71.09%. Notably, the failure probability of the earthquake induced cases is reduced if the catchment area in the prediction model is replaced by the peak flow of the dammed stream for these cases. In contrast, the predicted failure probability of the heavy rainfall-induced case increases if the high flow rate of the dammed stream is incorporated into the prediction model. Consequently, it is suggested that the prediction model using the peak flow as causative factor should be used to evaluate the stability of a landslide dam if the peak flow is available. Together with an estimation of the impact of an outburst flood from a landslide-dammed lake, the failure probability of the landslide dam predicted by the proposed logistic regression model could be useful for evaluating the related risk.     

环境与灾害监测预报小卫星CCD数据质量评价

中国环境与灾害监测预报小卫星星座双星4部CCD传感器具备大范围、全天时环境与灾害监测等方面的能力,在空间覆盖与重复观测频率方面有很大的优势。结合美国陆地卫星TM数据,从几何精度、辐射质量2个方面定量分析了该卫星CCD传感器的数据质量。结果表明：①环境减灾卫星CCD数据无波段错位现象,有极小的畸变与扭曲（0.05%）,然...     

沈阳地区大雾天气的UPS订正预报方法

选用2005-2009年沈阳地区5个气象站点的气象资料,总结了沈阳地区雾天的时空分布规律.沈阳地区一年中近一半的时间出现轻雾,大雾年平均16.4天;轻雾和大雾的季节分布都呈夏、秋季多,春季少的态势;大雾多发时段在清晨.在数值预报的基础上,利用UPS预报方法,进一步做出大雾天气订正预报,建立沈阳地区大雾天气UPS订正预报方法.当数值预报有大雾时,如T-Txover（最高气温出现时段温度露点差）≤5℃则可预报有大雾,当-4℃＜T-Txover≤5℃时可预报未来会出现能见度小于等于500 m的浓雾;如T-Txover≤-4℃则预报未来会出现能见度小于等于200m的强浓雾.如T-Txover＞5℃则有暖湿平流时预报有大雾,无暖湿平流时预报不会出现大雾.     

台站闪电定位仪维护方法与技巧

通过对闪电定位仪的基本构造、日常维护、常见故障等进行分析,找出闪电定位仪维护中存在的问题,提出一些有实用价值的维护维修方法,供台站在工作中参考.     

Seasonal and regional differences in long-term changes in large mesozooplankton (>505 μm) biomass and abundance in a semi-enclosed subtropical bay

Journal of Oceanology and Limnology - Obvious spatiotemporal heterogeneity is a distinct characteristic of ecosystems in subtropical bays. To aid targeted management and ecological restoration in...