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61.
利用2007—2011年MODIS、GlobAlbedo和ERA-Interim的3种地表反照率产品,借助地理信息系统(Geographic Information System, GIS)空间化技术,对中国地区3种地表反照率产品进行了对比分析。结果表明:3种产品与气象站观测值的时间分布趋势一致,冬季高夏季低,且相关性较高。3种产品中,MODIS与GlobAlbedo的绝对差异值最小,ERA-Interim与MODIS、GlobAlbedo的绝对差异值较大。3种产品在青藏高原和西北山地区域表现出较大的差异,且差异表现为冬半年高,夏半年低。3种产品之间相关性最高的是MODIS与GlobAlbedo,最低的是MODIS与ERA-Interim, 3种产品在40°N以北具有较好的相关性。且在夏季和冬季地表反照率均值的表现说明,ERA-Interim相比MODIS、GlobAlbedo难以反映地表反照率受地形和土地覆被的影响。 相似文献
62.
Bing LU Jiqin ZHONG Wei WANG Shihao TANG Zhaojun ZHENG 《Journal of Meteorological Research》2021,35(3):505-520
The green vegetation fraction(GVF) can greatly influence the partitioning of surface sensible and latent heat fluxes in numerical weather prediction(NWP) models. However, the multiyear averaged monthly GVF climatology—the most commonly used representation of the vegetation state in models—cannot capture the real-time vegetation state well. In this study, a near real-time(NRT) GVF dataset generated from an 8-day composite of the normalized difference vegetation index is compared with the 10-yr averaged monthly GVF provided by the WRF model. The annual variability of the GVF over North China is examined in detail. Many differences between the two GVF datasets are found over dryland, grassland, and cropland/grassland mosaic areas. Two experiments using different GVF datasets are performed to assess the impacts of GVF on forecasts of screen-level temperature and humidity. The results show that using NRT GVF can lead to a widespread reduction of 2-m temperature forecast errors from April to October.Evaluation against in-situ observations shows that the positive impact on 2-m temperature forecasts in the morning is more distinct than that in the afternoon. Our study demonstrates that NRT GVF can provide a more realistic representation of the vegetation state, which in turn helps to improve short-range forecasts in arid and semiarid regions of North China. Moreover, our study shows that the negative effect of using NRT GVF is closely related to the initial soil moisture. 相似文献
63.
Kidane Welde REDA Xingcai LIU Qiuhong TANG Tesfay Gebretsadkan GEBREMICAEL 《Journal of Meteorological Research》2021,35(4):673-689
The availability of satellite and reanalysis climate datasets and their applicability have been greatly promoted in hydro-climatic studies. However, such climatic products are still subject to considerable uncertainties and an evaluation of the products is necessary for applications in specific regions. This study aims to evaluate the reliability of nine gridded precipitation and temperature datasets against ground-based observations in the upper Tekeze River basin(UTB) of Ethiopia from 1982 to 2016. Precipitation, maximum temperature(T_(max)), minimum temperature(T_(min)), and mean temperature(T_(mean)) were evaluated at daily and monthly timescales. The results show that the best estimates of precipitation are from the Eart H2 Observe, WFDEI, and ERA-Interim reanalysis data Merged and Bias-corrected for the Inter-Sectoral Impact Model Intercomparison Project(EWEMBI), and the Climate Hazards Group Infra Red Precipitation with Station data(CHIRPS) datasets. The percentage biases and correlation coefficients(CCs) are within ±15% and 0.5, respectively, for both EWEMBI and CHIRPS at the two timescales. All products underestimate the drought conditions indicated by the standardized precipitation index(SPI), while the EWEMBI and CHIRPS datasets show higher agreement with the observations than other datasets. The Tmean estimates produced by the ECMWF ReAnalysis version 5(ERA5) and the Climate Hazards Group Infra Red Temperature with Station data(CHIRTS) are the closest to the observations, with CCs of 0.65 and 0.55, respectively, at the daily timescale. The CHIRTS and EWEMBI datasets show better representations of Tmax(T_(min)), with CCs of 0.69(0.72) and 0.62(0.68), respectively,at the monthly timescale. The temperature extremes are better captured by the ERA5(T_(mean)), CHIRTS(T_(max)), and EWEMBI(T_(min)) datasets. The findings of this study provide useful information to select the most appropriate dataset for hydrometeorological studies in the UTB and could help to improve the regional representation of global datasets. 相似文献
64.
Digital terrain analysis(DTA) is one of the most important contents in the research of geographical information science(GIS). However, on the basis of the digital elevation model(DEM), many problems exist in the current research of DTA in geomorphological studies. For instance, the current DTA research appears to be focused more on morphology, phenomenon, and modern surface rather than mechanism, process, and underlying terrain. The current DTA research needs to be urgently transformed from the study of landform morphology to one focusing on landform process and mechanism. On this basis, this study summarizes the current research status of geomorphology-oriented DTA and systematically reviews and analyzes the research about the knowledge of geomorphological ontology, terrain modeling, terrain derivative calculation, and terrain analytical methods. With the help of DEM data, DTA research has the advantage of carrying out geomorphological studies from the perspective of surface morphology. However, the study of DTA has inherent defects in terms of data expression and analytic patterns. Thus, breakthroughs in basic theories and key technologies are necessary. Moreover, scholars need to realize that DTA research must be transformed from phenomenon to mechanism, from morphology to process, and from terrain to landform. At present, the research development of earth science has reached the critical stage in which the DTA research should focus more on geomorphological ontology. Consequently, this study proposes several prospects of geomorphology-oriented DTA from the aspects of value-added DEM data model, terrain derivatives and their spatial relations, and macro-terrain analysis. The study of DTA based on DEM is at a critical period along with the issue on whether the current GIS technology can truly support the development of geography. The research idea of geomorphology-oriented DTA is expected to be an important exploration and practice in the field of GIS. 相似文献
65.
本实验研究分别采用益母草的根、茎、叶的0.10、0.25、0.50、2.00、1.00g/L和水苏碱的0.20、0.40、0.60、0.80、1.00g/L5个不同浓度梯度的处理液处理钉螺,设清水和0.001g/L浓度的氯硝柳胺溶液为对照。结果表明:(1)益母草各部分的水浸液均有很好的灭螺效果,用不同浓度的处理液浸杀钉螺,在不同时间的处理下,钉螺死亡率存在差异,其钉螺死亡率是随处理浓度的增加和时间的延长呈上升趋势,0.5g/L以上的益母草根、茎、叶、化水浸液和浓度达0.60g/L以上的水苏碱处理液均可达到100%的毒杀钉螺致死效果,与通常使用浓度0.001g/L氯硝柳胺溶液的灭螺效果相当。不过益母草根、茎、叶水浸液的毒效较氯硝柳胺略慢,用0.001g/L氯硝柳胺溶液处理钉螺2~3d可达100%的死亡率,而用0.5g/L以上的益母草根、茎、叶水浸液水溶液处理需要3~5d才能达到同样的效果;灭螺效果顺序依次为:叶>茎>根。(2)钉螺趋避性研究表明,水苏碱和益母草根、茎和叶的处理液对钉螺具有明显的驱逐作用,而盐酸益母草碱几乎没有作用。(3)并对其剂量-效应与时间-效应进行了研究分析,由此获得化感作用植物益母草灭螺的化学生态学证据,为研制新的具中国特色的植物成份灭螺剂打下了基础,并为合成仿生灭螺剂以及最终构建生态工程中强化感作用植物群落灭螺提供理论依据。 相似文献
66.
滇东北地区峨眉山玄武岩铜矿成矿物质来源 总被引:1,自引:0,他引:1
针对滇东北峨眉山玄武岩分布区铜矿中矿石矿物及玄武岩的微量元素Co,Cr,Ni,Pb,Th,U以及铅同位素组成进行研究,结果显示:在玄武岩和矿石中,Pb平均丰度分别为7.87×10-6和7.13×10-6,Th平均丰度分别为5.27×10-6和6.27×10-6,U平均丰度分别为1.16×10-6和0.97×10-6;从Th,U,Pb的质量分数揭示了玄武岩和矿石物源的相似性;Co,Cr,Ni的质量分数除矿石Cr略低外,玄武岩和矿石的Co和Ni均大于上部地壳平均值,提供了成矿物质非上部地壳来源的信息;铜矿石中主要矿物铅同位素组成(206Pb/204Pb平均18.3442、07Pb/204Pb平均15.620 22、08Pb/204Pb平均38.653 9)与玄武岩铅同位素组成(206Pb/204Pb平均18.805 32、07Pb/204Pb平均15.602 72、08Pb/204Pb平均39.250 8)相似,在206Pb/204Pb-207Pb/204Pb和206Pb/204Pb-208Pb/204Pb图中,二者铅同位素组成呈线性排列,从而在铅同位素示踪上显示了二者具有相同的铅源。由此判定滇东北峨眉山玄武岩区3类铜矿的成矿物质是源自于该区的玄武岩。 相似文献
67.
68.
晋城煤层气藏成藏机制 总被引:3,自引:0,他引:3
通过晋城煤层气的规模开发、压裂煤层气井的解剖、井下煤层瓦斯抽放、构造地应力场研究、煤储层大裂隙系统“CT”式解剖与煤层气封闭保存条件研究, 发现3#煤储层内部存在大量煤层气包, 构造微破裂作用促使煤层气包之间广泛合并联通, 煤层气包内部储层的非均质性弱化, 渗透率增加, 煤层气包内部的游离气体比例增加, 流体压力系统边界逐渐清晰并形成煤层气藏. 揭示煤层气藏的成藏机制, 认识煤层气藏的内部细节特征, 促进了该区的煤层气开发技术进步, 提高了井下煤层瓦斯的抽放效率. 相似文献
69.
为了研究利用小当量震源进行远距离探测的可能性,通过现场试验进行了研究.野外实验采用1次大当量激发和16次小当量激发,研究结果表明:①有可能利用数十公斤当量的炸药实现200km距离的探测;②在激发条件相同(或相近)时,不同当量的激发波形滤波后存在一定的相似性;③依据人工震源可重复性采用以下的激发组合方式和处理方法能够有效提高信噪比:针对大当量激发与小当量激发波形的相似性,利用大当量激发的波形作模板与小当量激发的波形作相关,可判断台站是否接受到小当量激发的信号并检测其震相到时信息.针对小当量激发波形的相似性,采用小当量多次激发的方式,通过N次根加权叠加方法,能有效提高记录的信噪比和震相识别精度. 相似文献
70.
考虑应用系统中如何安全、高效的进行统一的人员管理及权限管理问题,研究基于微软活动目录构建通用中间件并以WebService方式发布的解决方案。具体内容包括把活动目录作为统一的人员库;构建通用授权管理平台统一管理用户在不同的软件系统中的角色和权限;该管理平台以WebService的方式向其它的应用系统提供接口。文中示例表明该方案切实可行,应用范围广。 相似文献