INFLUENCE OF DIFFERENT-SCALE ERRORS INTERACTIONS ON ANALYSIS AND FORECAST OF REGIONAL NWP MODEL

In the previous study, the influences of introducing larger- and smaller-scale errors on the background error covariances estimated at the given scales were investigated, respectively. This study used the covariances obtained in the previous study in the data assimilation and model forecast system based on three-dimensional variational method and the Weather Research and Forecasting model. In this study, analyses and forecasts from this system with different covariances for a period of one month were compared, and the causes for differing results were presented. The variations of analysis increments with different-scale errors are consistent with those of variances and correlations of background errors that were reported in the previous paper. In particular, the introduction of smaller-scale errors leads to greater amplitudes in analysis increments for medium-scale wind at the heights of both high- and low-level jets. Temperature and humidity analysis increments are greater at the corresponding scales at the middle- and upper-levels. These analysis increments could improve the intensity of the jet-convection system that includes jets at different levels and the coupling between them that is associated with latent heat release. These changes in analyses will contribute to more accurate wind and temperature forecasts in the corresponding areas. When smaller-scale errors are included, humidity analysis increments are significantly enhanced at large scales and lower levels, to moisten southern analyses. Thus, dry bias can be corrected, which will improve humidity forecasts. Moreover, the inclusion of larger- (smaller-) scale errors will be beneficial for the accuracy of forecasts of heavy (light) precipitation at large (small) scales because of the amplification (diminution) of the intensity and area in precipitation forecasts.     

基于欧拉数的地籍拓扑关系计算

地籍实体间的空间拓扑关系是地籍信息系统时空数据组织与查询、空间数据质量控制、空间数据更新处理等的基础,然而现有拓扑关系模型在计算地籍实体间的拓扑关系方面存在不足。本文提出了一种基于目标整体交/差和欧拉数的地籍实体拓扑关系计算方法,其将目标看作一个整体,用目标整体间∩(交)、\(差)两个集合操作的结果来区分目标之间的拓扑关系,结果的取值包括内容、维数和欧拉数三个拓扑不变量。研究工作表明本文所提出的拓扑关系模型克服了现有拓扑关系模型在描述地籍实体间拓扑关系方面存在的不足,并且其已成功地应用到地籍空间数据更新处理中。     

多维粗差定位与定值的算法研究及实现

在概括控制网观测值粗差探测方法研究进展和讨论多雏粗差定位与定值理论的基础上，提出了多维粗差的搜索、判断和算法，并在控制网数据处理通用软件包中得到实现。通过算例分析，证明了算法的有效性；最后提出了粗差定位与定值时应注意的问题。     

基于Z-I关系和变分校正法改进雷达估测降水

将新回归系数估计法和新误差订正法应用于3 km的雷达CAPPI估测降水,首先用新的回归方法得出更合理的Z-I关系;再用基于变分技术的新的误差订正方法对估算出的降水进行订正,获得较好的估算结果,并且用2005年6月17～25日广东自动站降水和每6分钟一次的雷达基数据对新回归系数估计法和新误差订正法进行验证,结果表明:将新回归系数估计法和新误差订正法用于雷达估测降水,能更好地对雷达回波强度估算降水的一些常见误差进行校订.     

T213模式对强冷空气短期预报能力的分析检验

利用T213模式的500hPa高度、地面气压、850hPa温度预报格点资料和客观分析实况格点资料，对2001—2002年冬半年我国出现的8次强冷空气天气过程的主要影响天气系统进行了预报能力的客观分析检验。所得结果有利于数值预报产品的释用及实时预报业务。     

一种区域格点三维变分分析方案--基本框架和初步试验

给出一种区域格点三维变分分析方案的基本框架.对方案中阶数巨大的背景场误差协方差矩阵加以处理,选用位势高度和风场非平衡部分的纬向风速、经向风速作为分析变量,减少矩阵阶数;进行变量变换,避免矩阵求逆;然后,采用与最优插值方案相似的水平和垂直方向可分离的理想相关模型,在水平方向上用递归滤波器代替矩阵运算,从而实现变分分析方案的求解.用单个和理想分布观测资料对方案测试,并进行实例试验,得到很好的计算结果.     

Analysis of ice water path retrieval errors over tropical ocean

Retrieval of multi-layered cloud properties, especially ice water path (IWP), is one of the most perplexing problems in satellite cloud remote sensing. This paper develops a method for improving the IWP retrievals for ice-over-water overlapped cloud systems using Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) and Visible and Infrared Scanner (VIRS) data. A combined microwave, visible and infrared algorithm is used to identify overlapped clouds and estimate IWP separately from liquid water path. The retrieval error of IWP is then evaluated by comparing the IWP to that retrieved from single-layer ice clouds surrounding the observed overlapping systems. The major IWP retrieval errors of overlapped clouds are primarily controlled by the errors in estimating the visible optical depth. Optical depths are overestimated by about 10–40% due to the influence of the underlying cloud. For the ice-over-warm-water cloud systems (cloud water temperature Tw > 273 K), the globally averaged IWP retrieval error is about 10%. This cloud type accounts for about 15% of all high-cloud overlapping cases. Ice-over-super-cooled water clouds are the predominant overlapped cloud system, accounting for 55% of the cases. Their global averaged error is 17.2%. The largest IWP retrieval error results when ice clouds occur over extremely super-cooled water clouds (Tw 6 255 K). Overall, roughly 33% of the VIRS IWP retrievals are overestimated due to the effects of the liquid water clouds beneath the cirrus clouds. To improve the accuracy of the IWP retrievals, correction models are developed and applied to all three types of overlapped clouds. The preliminary results indicate that the correction models reduce part of the retrieval error.     

中国历史探空资料中的一些过失误差及偏差问题

利用综合静力学质量控制技术，分析中国历史探空资料集中的一些过失误差情况；着重研究了１９６０年代探空仪器变化给温度和湿度时间序列带来的不均一性问题；进一步讨论了中国近期探空温度和湿度资料中垂直层次上存在的一些偏差问题     

六自由度地震动测量方法及其误差分析

根据无陀螺捷联惯导原理,提出一种用八支力平衡加速度计测量六自由度地震动的方法,并对该测量方法的误差进行了分析。