基于地心坐标系的卫星导航测风平滑算法

本文从高空风探测原理出发,提出可业务化运行的卫星导航探空系统高空风平滑计算方法。该算法首先根据北斗〖CD*2〗GPS（Global Positioning System）双模式探空仪提供的大地坐标秒间隔数据,基于地心坐标系计算原始高空风;然后,采用矢量滑动平均法对原始数据进行平滑处理。通过与同球施放的芬兰RS92探空系统做比对分析得出,滑动平均窗口在0～32 km高度范围内设置为34 s、在32 km高度以上设置为60 s条件下,卫星导航探空系统与RS92探空系统高空风测量结果吻合较好。该算法计算结果同基于站心坐标系计算的30 s滑动平均风基本相同,但其风速分量误差范围在32 km高度以下略优、在32 km高度以上减小明显,升空全程误差范围更为稳定。     

多种模式降水预报的稳定性特征研究

预报的稳定性是指对同一时段在不同时间发布的多时效预报结论的一致性,是模式预报质量的一个重要方面,较大的不稳定性会给使用者造成困扰。为深入了解业务常用模式的稳定性,使用相对标准偏差指标计算不同时效预报的降水量波动大小,并改进了Flip-Flop指数（改进后简称FFnorm）,计算多时效降水量预报变化趋势的翻转程度,衡量预报变化趋势的稳定性,对2种全球模式（ECMWF、NCEP-GFS）、3种区域模式（CMA-MESO、CMA-SH9、HHUPS-ST）,在中国6个气候分区中降水预报的稳定性进行对比分析,分为实况有降水和暴雨及以上降水2种情况进行了讨论。结果表明：实况有降水时,相对区域模式来说,全球模式的多时效降水预报的相对标准偏差较小,即模式降水量预报的波动较小;各模式对西南区的西部、东北区的东部以及华南区的南部预报的波动性相对较小,西北区的西部波动性较大。就多时效降水量预报变化趋势而言,2种情况下均为CMA-MESO、NCEP-GFS和 ECMWF的稳定性较好,其FFnorm指数小于HHUPS-ST和CMA-SH9模式,其中CMA-MESO对西南区、华南部分地区降水量预报变化趋势的稳定性较为突出;CMA-SH9的指数最大,多时效降水量预报变化趋势稳定性较差;各模式对长江中下游地区的FFnorm指数相对较大,多时效预报趋势的稳定性较差。有降水时,CMA-MESO随时效临近的降水量预报变化趋势稳定（单调递增、单调递减或不变）的频次最多,其次是NCEP-GFS,2种降水情况下,该2种模式的降水量预报均为随时效临近单调递增次数大于递减次数,且CMA-MESO单调递增特征尤其显著。以上特征能够为模式调试和预报决策提供参考。     

Analysis of the contributions of topographic,soil, and vegetation features on the spatial distributions of surface soil moisture in a steep natural forested headwater catchment

Surface soil moisture has been extensively studied for various land uses and landforms. Although many studies have reported potential factors that control surface soil moisture over space or time, the findings have not always been consistent, indicating a need for identification of the main factors. This study focused on the static controls of topographic, soil, and vegetation features on surface soil moisture in a steep natural forested headwater catchment consisting of three hillslope units of a gully area, side slope, and valley‐head slope. Using a simple correlation analysis to investigate the effects of the static factors on surface soil moisture at depths of 0–20 cm at 470 points in 13 surveys, we addressed the characteristics of surface soil moisture and its main controlling factors. The results indicated that the mean of surface soil moisture was in the decreasing order of gully area > valley‐head slope > side slope. The relationship between the mean and standard deviation of surface soil moisture showed a convex‐upward shape in the headwater catchment, a negative curvilinear shape in the gully area, and positive curvilinear shapes at the side and valley‐head slopes. At the headwater catchment and valley‐head slope, positive contributions of soil porosity and negative contributions of slope gradient and saturated hydraulic conductivity were the main controlling factors of surface soil moisture under wetter conditions, whereas positive contributions of topographic wetness index and negative contributions of vegetation density were the main controlling factors of surface soil moisture under drier conditions. At the side slope underlain by fractured bedrocks, only saturated hydraulic conductivity and vegetation density were observed to be the controlling factors. Surface soil moisture in the gully area was mainly affected by runoff rather than were static features. Thus, using hillslope units is effective for approximately estimating the hydrological behaviours of surface moisture on a larger scale, whereas dependency between the main static factors and moisture conditions is helpful for estimating the spatial distributions of surface moisture on a smaller scale.     

Evaluating the spatiotemporal variations of water budget across China over 1951–2006 using IBIS model

The Integrated Biosphere Simulator is used to evaluate the spatial and temporal patterns of the crucial hydrological variables [run‐off and actual evapotranspiration (AET)] of the water balance across China for the period 1951–2006 including a precipitation analysis. Results suggest three major findings. First, simulated run‐off captured 85% of the spatial variability and 80% of the temporal variability for 85 hydrological gauges across China. The mean relative errors were within 20% for 66% of the studied stations and within 30% for 86% of the stations. The Nash–Sutcliffe coefficients indicated that the quantity pattern of run‐off was also captured acceptably except for some watersheds in southwestern and northwestern China. The possible reasons for underestimation of run‐off in the Tibetan plateau include underestimation of precipitation and uncertainties in other meteorological data due to complex topography, and simplified representations of the soil depth attribute and snow processes in the model. Second, simulated AET matched reasonably with estimated values calculated as the residual of precipitation and run‐off for watersheds controlled by the hydrological gauges. Finally, trend analysis based on the Mann–Kendall method indicated that significant increasing and decreasing patterns in precipitation appeared in the northwest part of China and the Yellow River region, respectively. Significant increasing and decreasing trends in AET were detected in the Southwest region and the Yangtze River region, respectively. In addition, the Southwest region, northern China (including the Heilongjiang, Liaohe, and Haihe Basins), and the Yellow River Basin showed significant decreasing trends in run‐off, and the Zhemin hydrological region showed a significant increasing trend. Copyright © 2009 John Wiley & Sons, Ltd.     

宽窄相间河道水流紊动特性试验研究

为了探索宽窄相间河道的水流紊动特性，以西南地区宝兴河上游宽窄相间河段为研究对象，基于室内概化模型试验，采用多普勒声学流速仪（ADV）测量了室内模型典型断面上的三维瞬时流速，分析典型断面上的纵向时均流速、紊动强度、雷诺切应力和紊动能的分布规律。试验结果显示：宽窄相间水槽中，扩散段边壁的紊动强度大于中心区域的紊动强度，最大值位于0.2倍水深处；扩散段两侧坡脚处紊动能最大；侧壁区的平面和立面雷诺切应力最大值出现在扩散段内，中心区域最大雷诺切应力位于两槽间的中间断面处；扩散段内水流紊乱，两侧出现旋涡和涡脱，易造成侧壁侵蚀加强，引起河道拓宽。深入分析了宽窄相间河道水流的紊动特性，可为山区河流治理和自然灾害防治提供参考。     

肇东和亳县陨石中的黑包体及其成因意义

肇东、毫县陨石中的黑包体在总体成分、形状、大小上与陨石球粒相似,但两者的内部结构以及矿物组合不同。黑包体中矿物呈密堆状,主要由细粒橄榄石以及其它硅酸盐微晶组成,不含火成玻璃等特点表明黑包体未经历过熔融,它们可能是形成球粒的毛坯。因此认为球粒的形成有三个阶段:星云凝聚形成尘粒—尘粒吸积形成黑包体—黑包体熔融形成球粒。     

肇东陨石高压加热—熔融实验研究

在30kbar压力下进行了肇东陨石的加热-熔融实验。实验结果表明。从840℃至2050℃,陨石中的金属-硫化物相经历了熔融—两相混溶的过程,最终形成一种Fe、Ni、Co、S之比不相等的多相混合物。而陨石中的硅酸盐相经历了热变质—熔融—熔融分异的过程。初熔温度为1610℃,2050℃时熔体发生分异,有富Si、Al的硅酸盐新相分离出来。以上述结果为依据,本文对类地行星早期层圈构造的形成机制进行了探讨和推论。     

Infinite Boundary Element in Two and Three Dimensional Problems

In this paper, the infinite boundary elements developed previously in two and three dimensional problems are reviewed, and the shortcoming and irrationality of interpolation functions of those elements are pointed out. A new interpolation function of infinite boundary element is proposed. The divergent integration on infinite element is also discussed in this paper.     

小尺度地形阻塞作用的数值试验

本文采用数值试验方法,讨论了一个高度只有200m的小尺度地形的阻塞作用,表明当大气低层的平均风速和温度层结使得Froude数小于1时,就有可能在地形的上风向形成阻塞。本文共试验了一般稳定层结、深厚逆温和浅薄逆温几种情况,讨论了数值结果和Froude数判别式之间的差异和原因,并计算了阻塞发生时的浓度分布。     

青藏高原模式大气(暂用)

本文根据青藏高原地区高空温、压、湿的气候资料并参考中纬度与热带模式大气初步建立了青藏高原不同季节的模式大气,以供该地区辐射传输研究的需要。