排序方式： 共有8条查询结果，搜索用时 171 毫秒
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在对高分辨率影像进行几何纠正、影像拼接以及制作正射影像图的基础上,制作了某实验区的三维地形景观,并利用SketchUp进行地物的精细建模同时通过ArcGIS 9.3进行三维显示和三维系统的二次开发。实验结果表明：利用高分辨率影像制作的三维地形具有地形逼真、清晰度高、信息量丰富等特点;完成了ArcGIS与三维建模软件的数据交换以及所建立模型的查询功能。 相似文献
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利用1961—2005年新疆地区最为齐全的整编台站观测资料集,分析了新疆地区夏季气温的时空变化特征,并探讨了引起这种时空变化的大气环流因子.结果表明:新疆地区的夏季气温首先表现出整体一致性的变化,在过去的45a中全疆气温持续上升,这与全球变暖的大背景相一致.影响新疆全疆夏季气温变化的主要大气环流因子为贝加尔湖附近高压脊的异常,当其偏强时,新疆地区夏季气温偏高,反之则偏低.新疆地区夏季气温第二类变化模态为南、北两疆反向的特征,这种变化模态主要表现在气温的年际时间尺度上.新疆南、北两疆气温反相变化主要是由伊朗高压和乌拉尔地区高压脊的变化所控制.当这两个大气环流系统在新疆地区造成中高层位势高度南北向正负异常时,新疆地区以天山为界夏季气温表现出反向的变化特征. 相似文献
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Contribution of the sea surface temperature over the Mediterranean-Black Sea to the decadal shift of the summer North Atlantic Oscillation 总被引：2，自引：0，他引：2
Recent observational study has shown that the southern center of the summer North Atlantic
Oscillation (SNAO) was located farther eastward after the late 1970s compared to before. In this study,
the cause for this phenomenon is explored. The result shows that the eastward shift of the SNAO southern
center after the late 1970s is related to the variability of the Mediterranean-Black Sea (MBS) SST. A
warm MBS SST can heat and moisten its overlying atmosphere, consequently producing a negative sea level
pressure (SLP) departure over the MBS region. Because the MBS SST is negatively correlated with the SNAO,
the negative SLP departure can enhance the eastern part of the negative-phase of the SNAO southern center,
consequently producing an eastward SNAO southern center shift. Similarly, a cold MBS SST produces an eastward
positive-phase SNAO southern center shift.
The reason for why the MBS SST has an impact on the SNAO after the late 1970s but why it is not the case
beforehand is also discussed. It is found that this instable relationship is likely to be attributed to
the change of the variability of the MBS SST on the decadal time-scale. In 1951--1975, the variability of
the MBS SST is quite weak, but in 1978--2002, it becomes more active. The active SST can enhance the
interaction between the sea and its overlying atmosphere, thus strengthening the connection between the
MBS SST and the SNAO after the late 1970s. The above observational analysis results are further confirmed
by sensitivity experiments. 相似文献
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Enhancement of the summer North Atlantic Oscillation influence on Northern Hemisphere air temperature 总被引：3，自引：0，他引：3
This study investigates the relationship between the summer North Atlantic Oscillation (SNAO)
and the simultaneous Northern Hemisphere (NH) land surface air temperature (SAT) by using the Climate
Research Unit (CRU) data. The results show that the SNAO is related to NH land SAT, but this linkage has
varied on decadal timescales over the last 52 years, with a strong connection appearing after the late
1970s, but a weak connection before. The mechanism governing the relationship between the SNAO and NH
land SAT is discussed based on the NCEP/NCAR reanalysis data. The results indicate that such a variable
relationship may result from changes of the SNAO mode around the late 1970s. The SNAO pattern was centered
mainly over the North Atlantic before the late 1970s, and thus had a weak influence on the NH land SAT.
But after the late 1970s, the SNAO pattern shifted eastward and its southern center was enhanced in
magnitude and extent, which transported the SNAO signal to the North Atlantic surrounding continents and
even to central East Asia via an upper level wave train along the Asian jet. 相似文献
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阿拉伯半岛-北太平洋型遥相关及其与亚洲夏季风的关系 总被引：3，自引：0，他引：3
利用相关分析和经验正交分解方法对过去57a NCEP-NCAR夏季亚洲-北太平洋地区海平面气压场进行了分析，揭示了一种新的遥相关模态，即阿拉伯半岛．北太平洋型遥相关（Arabian Peninsula-North Pacific Oscillation,APNPO）．研究表明，APNPO在本质上反映的是对流层低层北太平洋高压和南亚夏季风低压之间的一种共变特征，它的变化与亚洲夏季风的变化之间有着密切的联系．在年际尺度上，APNPO与东亚夏季风（East Asian summer monsoon, EASM）和南亚夏季风（South Asian summer monsoon, SASM）均存在显著的关联；在年代际尺度上，该遥相关与东亚夏季风的关系更为密切：两者均在20世纪60年代中期和70年代末发生了两次明显的年代际突变．通过分析与APNPO相关的环流场，探讨了APNPO与亚洲夏季风联系的物理过程．发现当APNPO偏强时，索马里急流、SASM气流、EASM气流以及南亚高压均得到加强，同时还通过高层的纬向波列在中国东北地区上空形成了一个异常的反气旋性环流．此外，强的APNPO还可加强对亚洲季风区的水汽输送，由此在印度半岛及中国华北地区造成强的水汽辐合．所有的这些大气环流和水汽条件的改变最终导致亚洲夏季风及印度和中国华北地区降水的异常．研究还发现APNPO的变化从春到夏具有较好的持续性，春季的APNPO与亚洲夏季风变化也存在显著的相关关系．从这个意义上讲，春季APNPO变化的超前性对于后期亚洲夏季风降水的预测具有潜在的重要参考价值． 相似文献
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2007年3月中国东部北方地区一次强灾害性暴风雪事件的成因初探 总被引：8，自引：0，他引：8
2007年3月3-5日,中国东部北方地区发生了近50年来历史同期最强的一次暴风雪事件,给该地造成了严莺的灾害和损失.通过分析这次暴风雪事件发生前期和同期的大尺度大气环流异常,探讨形成这次极端天气的可能物理机制.研究结果表明,在这次暴风雪事件发牛的前两周中,存在持续异常的北极涛动、南极涛动、欧亚型遥相关以及北太平洋涛动等大气模态.这些异常环流在中国东部沿岸地区引起了强劲的偏南风,由此给中国东部北方地区源源不断地输送暖湿空气,使得该地的水汽含量和气温不断升高,为这次暴风雪事件的发生准备厂良好的暖空气条件.当3月初大气环流发生调整,极地冷空气南下时,强劲的冷、暖空气交汇于中国东部北方地区,从而在该地形成了强大的冷锋系统,最终导致了这次强暴风雪事件的发生.研究结果表明,在预报与降水相关的天气时,必须考虑事发前期异常大气环流的信息,关注预报区域前期水汽的积累状况,这对于提高降水预报、特别是强降水预报的水平有着重要的意义. 相似文献
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