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91.
长江中下游旱涝中期预报方法及其业务应用   总被引:1,自引:1,他引:1  
金荣花  李月安  晁淑懿  任金声 《气象》2004,30(12):47-52
介绍了双层多因子综合相似的长江中下游旱涝中期预报模型。该模型引入了具有明确动力学和热力学意义的地转西风动量经向输送和经向温度梯度诊断量,同时强调了西太平洋副热带高压对长江中下游夏季降水的关键作用,并考虑了对流层中、低层500hPa高度和850hPa温度的大尺度环流背景场。与过去业务应用的单层相似预报模型相比较,不仅物理意义和天气学含义明确,而且更符合对具有复杂动力和热力机制的降水预报的考虑。5年的预报试验和业务应用结果表明,该方法对长江中下游地区旱涝的中期趋势预报有较好的预报能力。  相似文献   
92.
基于小波分解的西太平洋副热带高压模糊推理预测   总被引:3,自引:2,他引:3  
基于NCEP/NCAR再分析资料,讨论了西太平洋副高脊线与其前期位置的相互关系,并在此基础上用小波分解和自适应模糊推理方法,对副高脊线进行集成建模和预测.基于小波分解重构的副高脊线短期活动集成预测结果表明,该方法可有效降低预报难度,明显改进和提高了副高脊线短期活动的预报准确率.  相似文献   
93.
2003年异常气候对清徐葡萄的影响   总被引:1,自引:0,他引:1       下载免费PDF全文
气候对葡萄生长发育的影响十分关键,以光照、温度和降水三要素为主。利用清徐地面气象资料,根据葡萄各生育阶段对气候资源的需求特点,比照该时期年内的实际气候状况,着重分析年度内气候异常与葡萄产量下降、品质降低之间的关系,并就如何减缓气候对葡萄生产的不利影响进行初步探讨。  相似文献   
94.
任万辉  许黎  王振会 《气象》2004,30(6):3-7
综合论述了近 2 0年来中国稻田甲烷排放的研究状况 ,包括中国稻田甲烷排放通量的观测 ,稻田甲烷生成的生物学机理及产生、转化、传输的机理研究 ,稻田甲烷排放的影响因子 ,主要介绍了稻田甲烷产生和氧化过程、影响甲烷排放的因子  相似文献   
95.
The influences of the wintertime AO (Arctic Oscillation) on the interdecadal variation of summer monsoon rainfall in East Asia were examined. An interdecadal abrupt change was found by the end of the 1970s in the variation of the AO index and the leading principal component time series of the summer rainfall in East Asia, The rainfall anomaly changed from below normal to above normal in central China, the southern part of northeastern China and the Korean peninsula around 1978. However,the opposite interdecadal variation was found in the rainfall anomaly in North China and South China.The interdecadal variation of summer rainfall is associated with the weakening of the East Asia summer monsoon circulation. It is indicated that the interdecadal variation of the AO exerts an influence on the weakening of the monsoon circulation. The recent trend in the AO toward its high-index polarity during the past two decades plays important roles in the land-sea contrast anomalies and wintertime precipitation anomaly. The mid- and high-latitude regions of the Asian continent are warming, while the low-latitude regions are cooling in winter and spring along with the AO entering its high-index polarity after the late 1970s. In the meantime, the precipitation over the Tibetan Plateau and South China is excessive, implying an increase of soil moisture. The cooling tendency of the land in the southern part of Asia will persist until summer because of the memory of soil moisture. So the warming of the Asian continent is relatively slow in summer. Moreover, the Indian Ocean and Pacific Ocean which are located southward and eastward of the Asian land, are warming from winter to summer. This suggests that the contrast between the land and sea is decreased in summer. The interdecadal decrease of the land-sea heat contrast finally leads to the weakening of the East Asia summer monsoon circulation.  相似文献   
96.
顺义地裂缝成因与顺义-良乡断裂北段第四纪活动性讨论   总被引:3,自引:0,他引:3  
本文通过钻孔地层对比方法研究了顺义一良乡断裂北段的第四纪活动性,资料显示该断裂在第四纪期间呈现强弱交替的分期活动特征,距今315万年以来有3个较强活动期和3个较弱活动期,前三者分别距今266~315、171~228、73~147万年,后三者距今分别为228.266、147~171、0~73万年。中更新世晚期以来断裂活动不明显。超量开采地下水导致地面不均匀沉降是造成顺义地裂缝现今活动的主要原因。  相似文献   
97.
This paper describes the influence of siliceous and iron-rich calcic low-temperature hydrothermal fluids (LTHF) on the mineralogy and geochemistry of the Late Permian No. 11 Coal (anthracitic, Rr=2.85%) in the Dafang Coalfield in northwestern Guizhou Province, China. The No. 11 Coal has high contents of vein ankerite (10.2 vol.%) and vein quartz (11.4 vol.%), with formation temperatures of 85 and 180 °C, respectively, indicating that vein ankerite and vein quartz were derived from low-temperature calcic and siliceous hydrothermal fluids in two epigenetic episodes. The vein quartz appears to have formed earlier than vein ankerite did, and at least three distinct stages of ankerite formation with different Ca/Sr and Fe/Mn ratios were observed.The two types of mineral veins are sources of different suites of major and trace metals. Scanning electron microscope and sequential extraction studies show that, in addition to Fe, Mg, and Ca, vein ankerite is the dominant source of Mn, Cu, Ni, Pb, and Zn in the coal, and the contents of these five elements are as high as 0.09% and 74.0, 33.6, 185, and 289 μg/g, respectively. In contrast, vein quartz is the main carrier mineral for platinum-group elements (PGEs) Pd, Pt, and Ir in the coal, and the contents of Pd, Pt, and Ir are 1.57, 0.15, and 0.007 μg/g, respectively. Sequential extraction showed a high PGE content in the silicate fraction, up to 10.4 μg/g Pd, 1.23 μg/g Pt, and 0.05 μg/g Ir, respectively. It is concluded that the formation of ankerite and quartz and the anomalous enrichment of trace elements in the No. 11 Coal in the Dafang Coalfield, Guizhou, result from the influx of calcic and siliceous low-temperature hydrothermal fluids.  相似文献   
98.
The withdrawal of the Aral Sea tributaries (Amu and Syr Daria) for cultures has led to significant falls of its level and an important increase in its salinity. During the Holocene, a succession of low and high water inputs occurred. Silty deposits correspond to the high levels and carbonates to the low levels. This study makes a distinction between the Syr Daria and the Amu Daria water inputs during low-level periods by using mineralogical and chemical compositions of the carbonates deposits. Waters from the Syr Daria are more sulphatic and have a low iron content in comparison with that of the Amu Daria. The Syr Daria was the major tributary around 7500, 4956 and 970 yr?BP, whereas around 6200 and 3610 yr?BP, inflow also from the Amu Daria is observed. To cite this article: L. Le Callonnec et al., C. R. Geoscience 337 (2005).  相似文献   
99.
天津地区表土PAHs含量的多尺度空间相关性   总被引:1,自引:1,他引:1  
本文应用因子克立格分析方法,分析了天津表土16种PAHs之间多尺度空间结构特征。分析结果显示,天津表土PAHs在空间上可以划分三种尺度:块金尺度(0~5km),小空间尺度(5~10km)和大空间尺度(10~50km)。在不同的空间尺度上,16种PAHs之间表现出不同的空间相关性,具有空间尺度相关性。这种空间尺度相关性,是由于不同的空间污染过程造成的,有助于下一步的多尺度空间污染源的判断和污染物迁移转化规律的识别。  相似文献   
100.
We describe the non-primate mammalian fauna from the late Pliocene to earliest Pleistocene deposits of Mille-Logya in the Lower Awash Valley, Ethiopia, dated to c. 2.9–2.4 Ma, and divided into three successive units: Gafura, Seraitu, and Uraitele. We identify 41 mammalian taxa (including rodents), the most diverse group being the Bovidae, with 17 taxa. While the Gafura assemblage still resembles those from the earlier Hadar Formation, the younger Seraitu assemblage documents a major turnover. While there is little change in the species present across this interval, the relative abundances of various taxa change dramatically, with suids being largely replaced by open-country bovids (Alcelaphini and Antilopini). We interpret this faunal change as reflective of an environmental shift, contemporaneous with the replacement of Australopithecus afarensis by Homo in the area.  相似文献   
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