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GPS掩星资料(GPSRO)业务同化的正效果已经在多个国家的数值预报中心得到证实,但在新疆数值预报业务中尚未应用。为验证GPSRO同化对天山暴雪预报的影响,本文以GFS数据为背景场,用WRFDA同化了GPS掩星事件反演的折射率和温湿廓线,评估了其对2014年12月07日08时到09日08时的天山暴雪过程预报效果的影响,对比分析了两者同化产生的影响半径。研究发现,GPS掩星温湿廓线和折射率同化对此次天山暴雪过程预报均有正效果,改善幅度前者劣于后者。同化后风场U、V分量沿风向方向的影响半径均大于垂直风向方向,其增量极值中心位置向下风方向偏移。温度、湿度场的分析增量分布均接近各向同性,增量极值中心位置与掩星事件位置相对应。同化后温度分析均以增暖为主,湿度分析以增湿为主,气压分析以减压为主。温湿廓线同化产生的资料影响半径平均大于折射率同化产生的影响半径。并且,在任何网格点,无论是温度场还是比湿场,温湿廓线同化产生的分析差的绝对值大于折射率同化。温湿廓线与折射率同化后风场的分析增量整体上均随着高度的增加先减后增,温度场分析增量整体上随高度升高而增大,气压分析增量随高度升高单调递增, 比湿分析增量绝对值的大值区主要集中在500hPa以下的低空,其最大值位于700hPa附近。 相似文献
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二安替比林对羟基苯乙烯基甲烷与钒的高灵敏显色反应 总被引：1，自引：1，他引：0
合成了试剂二安替比林对羟基苯乙烯基甲烷 (DApHVM) ,研究了它与V(Ⅴ )的显色反应。在H3PO4介质中 ,Mn(Ⅱ )和Tween 2 0协同作用下 ,DApHVM与V(Ⅴ )生成红色产物 ,λmax为 540nm ,ε=1 0 3× 1 0 6 L·mol-1 ·cm-1 ,V(Ⅴ )的质量浓度在 0～ 50 μg/L内符合比尔定律。方法用于中草药及钢样中V(Ⅴ )的测定 ,结果与原子吸收法一致 ,加标回收率在 96%～ 1 0 5 % ,5次测定结果的RSD <3 5 %。 相似文献
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Laboratory experiments of depth-limited open-channel flows over a gravel bed were conducted in the study.Two gravel patches with identical individual element size and different lengths(3.81 m and 7.5 m)were tested.The depth-limited uniform flow regime with relative submergence S_r(= D/k_s) ranging from2.68 to 5.94 was produced by adjusting the tailgate weir.The velocity profiles were measured by using both an ultra-sound velocity profiler(UVP) and an acoustic Doppler velocimeter(ADV).The conventional methods used to determine the zero-plane displacement and estimate the bed shear velocity were then reviewed and compared.The measured double-averaged(DA) velocity profiles were found to fit well with the log law and defect law with a non-universal Karman constant κ./κ-value remains nearly constant and in the range from 0.2 to 0.3 for the long patch(LP) cases and κ-values are scattered within a wider range from 0.3 to 0.5 for the short patch(SP) cases.While the Br-value in log law remains constant and equal to 8.5 for LP cases,the Br-value was found to decrease with the increase of the dimensionless roughness height k_s~+ for SP cases.The streamwise turbulence intensity distributions were found to be independent on the patch length and agree well with the available experimental data in the intermediate region and wall region.The Manning resistance coefficient and Darcy-Weisbach friction factor were analyzed.The κ-value decreases to 0.22 for the fitting of the logarithmic flow resistance law under small relative submergence.The value of the integration constant Ar in the logarithmic law falls within the normal range between 3.25 and 6.25. 相似文献
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地震临界现象及相关尺度增长定量检测方法研究综述 总被引：1，自引：0，他引：1
当前作为强震前的典型特征,临界阶段地震活动的相关长度增长及主震周围矩释放加速(AMR)现象近年来受到广泛关注及普遍认可。但近期部分震例研究显示,在震中周围的大尺度范围内检测到矩释放加速的现象,而在震中附近较小区域又可检测到矩释放减速的现象。该文拟对地震活动相关以及临界状态的研究状况,主震前震区周围大范围矩释放加速和小范围矩释放减速定量化检测的国内外研究状况以及研究中所存在的问题作了综述。 相似文献
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中国自然灾害的空间分布特征 总被引：11，自引：1，他引：11
中国自然灾害的分布以秦岭－淮河线、胡焕庸线以及青藏高原外缘为界，可划分为四个大区，即北域、南域、西域和过滤带亚域。以灾害的单位面积失论，黄淮海地区是我国重点灾区，另一个重点区位于川、滇、黔、桂交界地段，它以人员的伤亡而突出。如果以灾害发生的总经济损定义灾害规模，则活动的规模中心位于以洞庭－武汉和郑州为两端点的地区。 相似文献
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雷达径向风观测在华北区域数值预报系统中的实时三维变分同化应用试验 总被引：5，自引：1，他引：4
以实现业务应用为目标开展了区域多部雷达径向风观测资料的三维变分直接同化应用研究。重点对背景场误差协方差的方差和尺度因子进行调整,形成能够与其他常规观测资料协同同化的雷达径向风同化方案,并建立了京津冀6部多普勒雷达观测资料的实时预处理系统。基于上述工作开展2011年汛期京津冀多普勒雷达径向风观测资料在华北区域快速更新循环同化和预报系统中的实时同化和对比试验,并对应用效果进行了初步评估。实时同化试验期间京津冀地区6部雷达经过质量控制后的径向风数据质量和同化情况的分析结果表明,同化系统有效地吸收了雷达径向风的观测信息并形成合理的分析增量,其中,S波段雷达观测的径向风数据数量、质量和稳定度均明显优于C波段雷达;整体来看,雷达径向风同化对地面和高空要素预报性能的影响基本为中性,且主要影响时段集中在最初的6 h。但降水预报评分结果表明,雷达径向风同化从降水强度、落区和范围等方面均明显提升了系统对对流尺度降水的短时预报性能。同时也应该看到,受制于目前3 h一次的同化更新频率,雷达资料同化的效果往往到对流临近时次才能体现。 相似文献
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LIU Hui Maeve S. Kelly Dirk A. Campbell DONG Shuanglin ZHU Jianxin WANG Sufeng 《中国海洋大学学报(英文版)》2007,6(2):175-181
A simple method for spiking formulated feed with domoic acid （DA） was developed in this study. DA feed was prepared by mixing 0.15 mL 100 μg mL-1 DA with 0.1 g formulated feed, and drying the mixture at room temperature for 2 h. The prepared DA feed contained 0.19 pg DA per particle. Of the added DA, 46.72% was retained in the feed. Relatively high DA retention （about 50%） was recorded after DA feed was soaked in water for 2h. Exposure to DA feed for 7d did not cause the increase of tissue DA level of adult king scallop （Pecten maximus） significantly in 60 d. The increase of their gonad index after DA exposure was not significantly different from the control. No significant change in DA level was found in spermary, ovary or fertilized eggs after DA exposure. These results indicated that DA excretion may be more efficient than DA accumulation under the current experimental conditions, and the mechanism of domoic acid incorporation in P. maximus may involve intracellular biotransformation. 相似文献
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T. Velusamy R. H. Becker W. M. Goss D. J. Helfand 《Journal of Astrophysics and Astronomy》1989,10(2):161-172
High resolution (11.7 to 64 arcsec) multifrequency radio observations of DA 495 (G 65.7 +1.2) at 20, 49 and 92 cm wavelengths
with the VLA, WSRT and OSRT are presented. A map of infrared emission in the surrounding region is also presented. Although
the remnant has a minimum near the centre, its brightness distribution does not show limb brightening. Hence it has characteristics
of both shell-type SNRs and Crab-type SNR. Alternatively it has an unusually thick shell with inner and outer radii of 125
and 500 arcsec respectively. The volume emissivity within the shell decreases radially outward. Its integrated flux density
spectrum is characteristic of a shell-type remnant. The role of the reverse shock in the formation of a thick shell is discussed.
The association of the open star cluster NGC6834 with DA 495 is also noted. The parameters of twenty-nine small diameter sources
detected around DA 495 are also presented. The radio source 1949 + 291 is associated with an IRAS source. 1948 + 292 may be
a Crablike pulsar-driven synchrotron nebula. The radio spectrum of the planetary nebula NGC 6842 is optically thick at 49
cm. 相似文献
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示波计时电位法测定矿石中的镓和铟 总被引：5，自引：0，他引：5
在ｐＨ５．０的茜素Ｓ－ＫＣ１－ＨＡｃＮａＡｃ－Ｌａ＾３＋溶液中,Ｇａ（Ⅲ）、Ｉｎ（Ⅲ）具有良好的示波图,其切口电位为－１．３８Ｖ和－０．８６Ｖ（ｕｓ．ＳＣＥ）。可分别进行测定。镓的质量浓度在１００～１８００ｕｇ／Ｌ内、铟的质量浓度在５～１４０ｕｇ／Ｌ内与切口高度呈良好的线性关系,检出限Ｇａ为９０ｕｇ／Ｌ及Ｉn为５ｕｇ／ Ｌ。通过萃取与干扰元素分离之后,对闪锌矿、锡石样品中的镓、铟测定,８次测定的ＲＳ 相似文献