改进的最优窗宽理论对年径流量的插值预测研究——以黄河利津等站为例

针对小样本数据造成年径流量预测效果不理想的情况,以及非对称和非正态资料的处理问题,引入信息扩散和模糊映射思想,同时运用遗传算法改进最优窗宽理论,建立了新的扩散插值模型。该模型通过对零散数据点的信息进行模糊扩散,进而实现对有限数据点信息向其邻近区域点的概率插值。选取黄河利津站为例,根据其近70 a(1942—2011年)径流量实测数据,进行了缺损数据的插值和预测试验,同时与正态扩散插值模型进行对比分析,结果表明:1)预测值能较好地模拟实际径流序列的波形变化,对丰水年(如2007年)和枯水年(如2009年)的预报都比较准确;2)中长期预报(10a)平均相对误差仅为11.59%,相较传统方法有较大的改进;3)以黄河流域2个站点(花园口和兰州)和长江流域的3个站点(朱沱、宜昌和大通)年径流量预测试验以及海温资料的插值试验作为补充,验证了该算法的有效性和普适性。该模型可为实际水文数据资料的客观分析和中长期预报提供参考。     

基于“永盛轮”航线冰情分析的北极东北航线通航性研究

海冰冰情是开发、利用北极航道的关键信息,研究利用2006—2015年北极地区逐日海冰密集度数据,根据2013年"永盛轮"首航北极东北航道时所经航线为例,提取了航线冰情要素,包括航线通航窗口、逐日海冰密集度时空分布以及海冰密集度月标准差等,对航线通航条件进行了研究。根据航线冰情要素获得了十年间航线通航窗口的基本情况,十年间航线所经水域的大体通航情况和主要冰障位置,7—10月份航线所经水域海冰密集度的变化动态。通过对航线冰情要素的分析,得出影响航线的两个关键海域,并分析了"永盛轮"航线与关键水域航线通航窗口的变化趋势。     

Exploring the performance of spatio-temporal assimilation in an urban cellular automata model

Urban cellular automata (CA) models propagate and accumulate errors during the modeling process due to the model structure or stochastic processes involved. It is feasible to assimilate real-time observations into an urban CA model to reduce model uncertainties. However, the assimilation performance is sensitive to the spatio-temporal units in the assimilation algorithm, that is, spatial block size and window length (temporal interval). In this study, we coupled an assimilation model, an ensemble Kalman filter (EnKF) and a Logistic-CA model to simulate the urban dynamic in Beijing over a period of two decades. Our results indicate that the coupled EnKF-CA model outperforms the CA-alone counterpart by about 10% in terms of the figure of merit, which reflects the agreement of modeled pixels. We also find that the assimilation performance using a finer block (1 km) is better than that using a coarser block (5 km and 10 km) because of the better depiction of spatial heterogeneity using a finer block. Moreover, the improvement of intermediate outputs using the coupled EnKF-CA model is effective for a certain period (e.g. 5 years). This implies that a high-frequency assimilation may not significantly improve the model performance. The sensitivity analyses of spatio-temporal assimilation in the EnKF-CA model provide a better understanding of the assimilation mechanism that couples with land-use change models.     

卢龙地区S波偏振与上地壳裂隙各向异性

由三分量数字地震仪组成的小孔径流动台网记录了1982年10月19日河北卢龙M_s=6.1级地震的部分余震.用质点运动图的方法对横波的偏振进行了分析。研究结果表明,在横波窗内的各观测点都存在横波的分裂现象.不同离源角和方位角快波偏振的水平投影都具有近NE40°方向的优势取向,与根据卢龙地震两组断层错动在各向同性介质中所辐射的横波的偏振方向不一致.这可以由传播介质中应力所导致裂隙的定向排列来解释.这一观测结果提供了卢龙地区脆性上地壳大范围膨胀各向异性（EDA）的证据,并表明这一地区直立平行排列裂隙取向和水平主压应力的方向为NE40°.     

光学遥感影像DCM-HTM去雾算法研究

针对卫星遥感影像的雾区检测和校正问题,提出了一种暗通道图像DCM与雾厚度图像HTM结合的DCM-HTM遥感影像去雾算法。算法基于暗通道原理,采用mean-shift均值漂移滤波和直方图自动阈值来检测雾区域;同时通过不重叠窗口获取HTM;最后在检测出的雾区内实现去雾校正处理。实验结果表明,算法能较准确地检测出影像上的雾区域,能在影像正常区域不受影响的前提下,有针对性地对受雾影响区域进行校正,校正效果较整幅影像的去雾校正有较大改善。     

日本九州岛地震震前电离层TEC异常

采用IGS发布的GIM数据,提出了一种结合滑动时窗法和临近格网点电离层TEC相关性分析法的联合分析方法,研究了震前电离层异常变化与地震的关系。通过分析震区附近5个格网点TEC的异常变化情况,发现震前电离层TEC发生明显异常变化,且格网点之间的TEC序列相关性受地震显著影响;通过分析二维电离层图的TEC异常空间分布,发现震前三天震中附近分别出现6h、12h和6h的异常。最后利用电离层层析的方法,对电离层异常时刻进行了电子密度的反演,进一步分析了电子密度在电离层异常时刻的分布情况。     

Deep petroleum occurrences in the Lower Kura Depression, South Caspian Basin, Azerbaijan: an organic geochemical and basin modeling study

High sedimentation rates (as much as 2500 m/Ma) during Pliocene-Pleistocene, with a resultant undercompacted section as thick as 10,000 m, and lower than normal geothermal gradients are the main characteristics which have created all the means for generation and preservation of oil at deep layers in the Lower Kura Depression.Oils collected from eight different oil fields for analyses seem to have originated from a common source rock which probably is clastic, deposited in relatively subanoxic to suboxic transitional marine environment receiving low to moderate input of terrestrial organic matter.Oils from shallow (< 3000 m) and cold (< 70–80°C) reservoirs have been altered to various extent by bacterial activity.A computer-aided basin modeling study has been carried out to outline the spatial variation of the oil window and thus help in further identification of possible source rocks for the reservoired oil in the Lower Kura Depression. Results suggest that the potential hydrocarbon source horizons of the Miocene and Pliocene Red Bed Series of the so called Productive Succession are, even at depocenter areas, immature with respect to oil generation, and thus, are very unlikely to have been source rocks for the reservoired oils. However, the Oligocene-Lower Miocene Maykop rocks are marginally mature to mature depending on locality and the Eocene and older rocks are mature with respect to oil generation at all representative field locations. Oil generation commenced at the end of Pliocene and continues at present at depths between 6000 and 12,000 m.An unusually deep (> 10,000 m) oil window in the depocenter areas has been caused by the depressed isotherms due to extremely high sedimentation rates (up to 3000 m/Ma) for the last two million years. The main phase of oil generation is taking place at depths greater than what most of the wells in the study are have reached.     

定量与定性分析在2017年精河MS6.6地震中的应用

为准确提取震前异常信息,以2017年新疆精河M_S6.6地震为例,基于乌鲁木齐台站W-N(k)测段数据,利用离差统计分析方法与原始曲线分析方法分别从定量与定性两个角度研究了地震前后的数据异常特征。结果显示,震前测段数据的变差系数成倍增大,离差分布曲线偏离正态分布,原始曲线出现大幅转折,断层活动形式出现明显变化,震后异常特征消失。通过效果图可知,结合两种方法分析数据异常具有一定的可行性,能为震前异常识别提供参考。     

一种改进的SAR图像聚焦算法

针对现有的相位梯度自聚焦(phase gradient autofocus,PGA)算法的加窗方法和特显点选取所存在的问题,提出一种改进的PGA算法。该算法提出一种新的确定相位误差点扩展函数支撑域的方法,此方法计算方位向上能量分布的平均值作为支撑域外的平均能量,以此来确定加窗的宽度。基于这种自适应加窗方法,还提出一种改进的特显点选取方法,该方法能够选择信杂比大的特显点,去掉信杂比小的特显点。试验结果表明,与传统的加窗方法和特显点选取方法相比,该方法能够得到更好的聚焦效果。