衡量地电阻率观测资料内在质量的一种方法   总被引：5，自引：0，他引：5       下载免费PDF全文

赵和云  丁卉  韩德胜 《地震工程学报》1999,21(2):156-159

提出了一种衡量地电阻率观测资料内在质量的方法。该方法综合了仪器精 度、环境干扰、季节变化、观测信噪比等因素,能对观测资料的质量给出公正、合理的 评价。  相似文献   

江苏省雷达降水估测集合分析          下载免费PDF全文

朱彦威  李雨嫣  康志明  李杨 《大气科学学报》2023,46(2):310-320

使用2019年、2020年5—8月江苏省降水分析场及站点观测资料,生成具有定量降水估测(Quantitative Precipitation Estimation, QPE)不确定性时间和空间结构的集合QPE,并用观测降水对集合QPE进行了确定性和概率性检验。确定性验证说明集合QPE能在总体上减小降水量的绝对误差和均方根误差,但也加重了某些区域的降水低估。集合平均能提高估测降水的准确率并减小空报率,也会使漏报增多,这使小雨的TS评分有所降低,但各量级降水TS评分仍能保持在较高水平。集合QPE对各量级降水都有较优的Brier评分,降水量级越大,估测效果越好。集合的离散度较小,且将集合成员排序后,观测值落在两头的频率更高,也反映了离散度偏小。此外,观测值大于集合成员最大值的频率更高,说明集合QPE倾向于低估降水。随着概率阈值的增大,集合估测降水发生的命中率(POD)和假警报率(POFD)逐渐增大,但POD增大的程度比POFD大得多,使相对作用特征曲线为折线。不同概率阈值下的POD和POFD体现了集合QPE对各量级降水都有较高的估测技巧,其中对小雨和中雨分辨能力最好。集合估测小雨和特大暴雨发...  相似文献   

The refined spatiotemporal representation of soil organic matter based on remote images fusion of Sentinel-2 and Sentinel-3     

《International Journal of Applied Earth Observation and Geoinformation》2020

Remote sensing technology is important for soil organic matter (SOM) estimation, but existing studies have mainly relied on a single data source. This limitation makes it difficult to simultaneously ensure high spatial resolution, high spectral accuracy and refined temporal granularity simultaneously, which cannot meet the requirements of the spatiotemporal dynamics representation. This study aimed to introduce a new remote sensing image source into SOM modeling and spatiotemporal estimation generated by fusing together Sentinel-2 and Sentinel-3 remote sensing images that have a 5-day revisit cycle; 10 m spatial resolution; and 21 different bands in blue, green, red and NIR spectral ranges. According to the image fusion process, a total of 52 available images were acquired between November 2016 and December 2018 in Donghai County, China. The fused images were used for SOM estimation model associated with 107 field samples. The results indicated that, first, the optimal model consisted of the band reflectivity (B20) and RVI (B18/B9), which were derived from the fused images, and the R² approached 0.7 in the two phases of the synchronized data. Second, the modeling accuracy was influenced to some extent by the actual SOM content. The R² values exceeded 0.75 when the SOM content was higher than 24 g/kg, while the R² was even lower than 0.35 when the SOM content was lower. Third, the averaged SOM contents remained stable in general, while the seasonal variances can also be found during the two-year interval. The SOM contents maintained a low level during autumn and winter, while higher SOM levels were found in the spring and summer. Finally, the spatial variations could be described as ‘low in the west and high in the east’. In summary, the spatiotemporal dynamics of SOM highlighted the necessity of modeling with fused remote sensing images, and more effective modeling could be expected with the continued increase in SOM in future.  相似文献   

Contribution of different generations of the brown shrimp Crangon crangon (L.) in the Dutch Wadden Sea to commercial fisheries: A dynamic energy budget approach     

Joana Campos  Henk W. Van der Veer  Vnia Freitas  Sebastiaan A.L.M. Kooijman 《Journal of Sea Research》2009,62(2-3):106

In this paper a contribution is made to the ongoing debate on which brown shrimp generation mostly sustains the autumn peak in coastal North Sea commercial fisheries: the generation born in summer, or the winter one. Since the two perspectives are based on different considerations on the growth timeframe from settlement till commercial size, the Dynamic Energy Budget (DEB) theory was applied to predict maximum possible growth under natural conditions. First, the parameters of the standard DEB model for Crangon crangon L. were estimated using available data sets. These were insufficient to allow a direct estimation, requiring a special protocol to achieve consistency between parameters. Next, the DEB model was validated by comparing simulations with published experimental data on shrimp growth in relation to water temperatures. Finally, the DEB model was applied to simulate growth under optimal food conditions using the prevailing water temperature conditions in the Wadden Sea. Results show clear differences between males and females whereby the fastest growth rates were observed in females. DEB model simulations of maximum growth in the Wadden Sea suggest that it is not the summer brood from the current year as Boddeke claimed, nor the previous winter generation as Kuipers and Dapper suggested, but more likely the summer generation from the previous year which contributes to the bulk of the fisheries recruits in autumn.  相似文献   

利用卷积神经网络开展偏振雷达定量降水估测研究     

蔡康龙  胡志群  谭浩波  黄锦灿  张伟强  张晶晶  植江玲 《热带气象学报》2024,(1):64-74

利用偏振升级改造后的广州新一代天气雷达（CINRAD/SAD）水平反射率ZH、差分传播相移率KDP、差分反射率因子ZDR和广东佛山219个地面气象自动站雨量数据,形成不同偏振量组合的8个数据集。基于卷积神经网络（CNN）,建立雷达定量降水估测网络架构QPEnet, 并将该架构用于雷达定量降水估测（QPE）,评估结果表明：数据集通道数N的增加可降低QPEnet的定量降雨估测的均方根误差（RMSE）,并提高相关系数（CORR）;对于由ZH形成的数据集Z、Z_1~3 km和Z_6 min,随着通道数N的增加,数据集Z、Z_1~3 km和Z_6 min的性能逐步得到提高,数据集Z_1~3 km和Z_6 min的均方根误差（RMSE）分别是4.71和3.78,比数值集Z分别降低了1.3%和18.7%;数据集Z_1~3 km和Z_6 min的CORR分别是0.82和0.88,比数据集Z分别提高了2.5%和10.0%;对于ZH、KDP和ZDR偏振量组成的数据集里面,数据集Z_ZDR_KDP的拟合性能最好,RMSE为3.97,比数据集Z的RMSE降低了14.6%,CORR是0.86,比数据集Z提高了7.5%;分别对0.6～5 mm、5～10 mm、10～20 mm、20～30 mm、30～40 mm、40～50 mm和50 mm以上的7个降水量级的均方根误差（RMSE）、平均偏差比（MBR）、平均误差（AE）和相对误差（RE）等的统计结果表明,数据集Z_6 min降雨精度最高。  相似文献   

对流层延迟对GPS大地高的影响     

沈飞  安艳辉 《现代测绘》2011,34(3):7-9

分析了对流层延迟的基本特性及常用的处理措施,通过实例表明了不同对流层的处理方法对大地高精度有较大影响:当基线两端高差较大时,即使基线较短,其气象条件也有所差异,仅仅通过差分或模型改正仍不能消除对流层延迟的影响,残余的对流层延迟仍然影响大地高的解算精度,通过对残余对流层延迟进行估计能够明显改善大地高的精度。  相似文献   

Empirical-statistical models based on remote sensing for estimating the volume of landslides induced by the Wenchuan earthquake   总被引：2，自引：1，他引：1  

Jianrong Fan  Xiuzhen Li  Fenfen Guo  Xiang Guo 《山地科学学报》2011,8(5):711-717

The Wenchuan Ms 8.0 earthquake on May 12, 2008 induced a huge number of landslides. The distribution and volume of the landslides are very important for assessing risks and understanding the landslide - debris flow - barrier lake - bursts flood disaster chain. The number and the area of landslides in a wide region can be easily obtained by remote sensing technique, while the volume is relatively difficult to obtain because it requires some detailed geometric information of slope failure surface and sub-surface. Different empirical models for estimating landslide volume were discussed based on the data of 107 landslides in the earthquake-stricken area. The volume data of these landslides were collected by field survey. Their areas were obtained by interpreting remote sensing images while their apparent friction coefficients and height were extracted from the images unifying DEM (digital elevation model). By analyzing the relationships between the volume and the area, apparent friction coefficients, and the height, two models were established, one for the adaptation of a magnitude scale landslide events in a wide range of region, another for the adaptation in a small scope. The correlation coefficients (R2) are 0.7977 and 0.8913, respectively. The results estimated by the two models agree well with the measurement data.  相似文献   

植被覆盖度遥感估算研究进展   总被引：24，自引：0，他引：24  

贾坤  姚云军  魏香琴  高帅  江波  赵祥 《地球科学进展》2013,28(7):774-782

植被覆盖度是刻画地表植被覆盖的重要参数,在全球变化研究、地表过程模拟和水文生态模型中发挥着重要作用.遥感能够反映不同空间尺度的植被覆盖信息及其变化趋势,是获取区域及全球植被覆盖度参数的一个重要手段.综合分析了用于植被覆盖度估算的遥感数据源,包括高光谱数据、多光谱数据、微波数据和激光雷达数据.而且分析了各种常用的植被覆盖度遥感估算方法及其优缺点,并评价了现有基于遥感数据的植被覆盖度产品及存在问题.最后,针对目前研究中存在的问题,讨论了植被覆盖度遥感估算研究的发展趋势,指出高时空分辨率长时间序列的全球植被覆盖度数据集、多源遥感数据融合和同化技术是未来植被覆盖度遥感估算研究的主要方向.  相似文献   

区域蒸散发遥感估算方法及验证综述   总被引：7，自引：0，他引：7  

张荣华  杜君平  孙睿 《地球科学进展》2012,27(12):1295-1307

蒸散发是地表水热平衡的重要参量,也是农作物生长状况和产量的重要指标。与传统的蒸散发计算方法相比,遥感技术经济、适用、有效,在非均匀下垫面的区域蒸散发监测上具有明显的优越性。系统回顾了5种常用的区域蒸散发遥感估算方法,包括经验统计模型、与传统方法相结合的遥感模型、地表能量平衡模型、温度—植被指数特征空间模型以及陆面过程与数据同化等,分析了这些模型的最新研究进展及各自的优缺点,并对地表蒸散发的地面验证方法进行了概述。最后简要分析了区域蒸散发遥感估算存在的问题,并展望了其未来发展趋势。多源遥感数据协同反演与非遥感参数遥感化、蒸散发模型改进与多模型集成、陆面过程与遥感数据同化、遥感蒸散发估算及地面验证中的尺度问题与空间代表性问题研究等将会是未来区域蒸散发研究中的重点发展方向。  相似文献   

梁河锡矿综合成矿信息定量模型的建立与预测     

丁秀芳  高建国  陶莉  赵长江 《云南地质》2008,27(4):483-490

采用网络化单元法划分单元,运用多元数学地质理论和方法进行单元块综合信息计算和单变量、复合变量的提取,界定找矿信息量值,建立综合成矿信息定量模型,从而优选成矿靶区和并进行验证。  相似文献