集合预报方法研究及应用进展综述

简要介绍了国内外集合预报研究及业务应用进展。涉及集合预报的4个方面：初始扰动生成、数值模式选择、预报信息提炼和预报系统及结果评价。结果可供改进我国集合预报业务的研究工作参考。     

Kalman filter estimation model in flood forecasting

Elementary precipitation and runoff estimation problems associated with hydrologic data collection networks are formulated in conjunction with the Kalman Filter Estimation Model. Examples involve the estimation of runoff using data from a single precipitation station and also from a number of precipitation stations. The formulations demonstrate the role of state-space, measurement, and estimation equations of the Kalman Filter Model in flood forecasting. To facilitate the formulation, the unit hydrograph concept and antecedent precipitation index is adopted in the estimation model. The methodology is then applied to estimate various flood events in the Carnation Creek of British Columbia.     

消除浅海水下冲击声源多次脉动几种方法的研究

采用匹配滤波器来消除浅海水下冲击声源多次脉动对测量的影响。其结果具有节省内存,计算速度快的优点,与维纳滤波一样。还对比研究了去卷积滤波和预测维纳滤波两种方法。指出在浅海水域,这两种方法的效果均不理想。     

Phenotypic plasticity of Vermetidae suspension feeding: a potential bias in their use as Biological Sea-Level Indicators

Some organisms represent useful Biological Sea‐Level Indicators (Bio SLI) thanks to their constant position relative to sea level and allow the reconstruction of past sea level changes. The sessile gastropods Vermetidae are among the most used indicators, since their shells often resist time averaging and can be easily dated with ¹⁴C. However, all these vermetids have a level of precision (± 0.5–1 m), obtained from data on the Mediterranean Dendropoma petraeum (Monterosato, 1884). We found a certain degree of plasticity in this species; it can also live subtidally, not in correspondence with the main sea level, where it feeds adopting a mixed feeding strategy. Considering this variability and the almost complete lack of knowledge for other Bio SLI vermetids, it appears clear that a common value of precision cannot be maintained and the precision of other vermetid species remains to be tested.     

Sequential forecasting of the surface and subsurface conditions in the Japan Sea

This study estimates a realistic change of the Japan Sea by assimilating satellite measurements into an eddy-resolving circulation model. Suboptimal but feasible assimilation schemes of approximate filtering and nudging play essential roles in the system. The sequential update of error covariance significantly outperforms the asymptotic covariance in the sequential assimilation due to the irregular sampling patterns from multiple altimeter satellites. The best estimates show an average rms difference of only 1.2°C from the radiometer data, and also explain about half of the sea level variance measured by the altimeter observation. The subsurface conditions associated with the mesoscale variabilities are also improved, especially in the Tsushima Warm Current region. It is demonstrated that the forecast limit strongly depends on variable, depth, and location.     

数学形态学方法在海面船目标检测中的应用

为进一步提高检测精度，提出1种将数学形态学方法应用到船目标检测数据后处理中的算法，根据该算法设计的数学形态学滤波器可以有效地消除SAR图像斑点噪声在船目标检测中造成的影响，减少船目标检测的误判，提高参数估计准确性。     

北斗卫星伪距多路径系统偏差的修正方法及其对单频PPP的影响分析

北斗伪距观测值存在特有的多路径系统性偏差,偏差的数量级达到几个分米到米。该系统偏差可分为两类:一类是IGSO/MEO卫星随高度角变化的伪距系统性偏差;另一类是GEO卫星(高度角仅微小变化)明显的伪距系统性偏差。系统性的伪距偏差导致GEO卫星MP序列的标准偏差较大,本文针对GEO卫星伪距偏差问题提出了一种基于卡尔曼滤波的修正方法,修正后的GEO卫星MP序列的标准偏差下降了10%~16%。基于伪距相位组合的单频PPP技术的伪距权重较大,会受到北斗伪距偏差的影响,分析表明该系统性偏差将导致单频PPP定位结果高程方向产生约1m的偏差。对GEO伪距偏差采用提出的卡尔曼滤波修正方法进行修正,并应用Wanninger和Beer的高度角模型消除IGSO/MEO观测值伪距偏差,本文对修正后的单频精密单点定位精度进行了分析。4个multi-GNSS experiment(MGEX)站10d观测数据的分析结果表明:仅改正和卫星多路径误差,高程方向定位结果精度可改善65%左右;采用本文方法对GEO卫星的多路径修正后,该方向定位结果精度改善比例将进一步提高至75%左右。     

基于修正嵌入式容积卡尔曼滤波的相位展开算法

针对干涉图展开问题,将Levenberg-Marquardt方法修正后的嵌入式容积卡尔曼滤波器应用于缠绕相位图像的展开中,结合基于修正矩阵束模型的局部相位梯度估计算法以及量化跟踪策略,提出一种基于修正嵌入式容积卡尔曼滤波的相位展开算法。该算法不仅可以精确和快速地展开缠绕像元,还可以在展开缠绕像元的同时抑制相位噪声,降低前置预滤波器的难度与复杂度,甚至可以在处理受噪声污染不严重的干涉图时免去前置预滤波处理步骤。试验结果表明本文算法具有较高的效率和良好的稳键性。     

GNSS测站速度估计模型重建

获取准确的GNSS测站速度对于研究全球板块运动、地壳形变、地震活动及其地球动力学过程至关重要。为此,以GNSS基线解算后的基线向量作为观测值,重建了最小二乘综合速度解算模型和卡尔曼滤波速度估计模型。模型中,考虑了测站坐标、运动速度、年、半年周期项一同作为参数,在基线解网平差的同时,一并求解获取速度估值。同时,利用坐标时序分析的方法,顾及白噪声和幂律噪声的影响,对单日解坐标时间序列重建了时序速度拟合估计模型,以获取长期趋势项作为速度值。基于3种模型,对川滇地区中国地壳运动观测网络2010—2014年21个GPS基准站的观测数据进行了速度估计与对比分析。结果表明:3种模型所估计测站速度非常接近,差异基本处于0~1mm/a范围之内;速度估值中误差均在亚毫米水平。由此得出,3种速度估计模型具有本质的一致性,均可正确估计测站运动速度,能够满足高精度地壳形变研究的需要。