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341.
正确认识天山北坡城市群的空间组织结构以及空间发展形态,对于完善绿洲城市群的发展理论和规划具有重要意义。以天山北坡城市群为研究对象,通过资源环境承载力的分析,总结出未来城市群发展面临的客观制约因素;通过中心性分析、断裂点理论修正的Voronoi多边形等方法识别出城市群的中心城市及各自的辐射范围城市;通过引力模型识别出城市之间的社会经济联系强度。据此,利用多维尺度分析的方法,可视化地展现了天山北坡城市群发展的空间组织形态。经调查了解:(1)乌鲁木齐市与克拉玛依市是未来城市群发展的两个中心城市,五家渠市、阜康市、昌吉市、石河子市周边目前属于乌鲁木齐市的辐射范围城市,奎屯市,乌苏市属于克拉玛依市的辐射范围城市;(2)城市群内部的城市之间的联系比较松散,特别是两个中心城市之间联系较弱;(3)城市群的空间发展形态为串珠式,是一种特殊的走廊式空间形态。 相似文献
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建筑物在施工、运营阶段受主体荷载等各种因素影响会产生沉降变形,为了利于建筑物沉降分析,保障建筑物安全,分析了分形理论在建筑物沉降数据处理中的可行性。通过实例,得出了基于分形理论的建筑物沉降数据处理方法。 相似文献
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The Impact of Mid- and High-Latitude Rossby Wave Activities
on the Medium-Range Evolution of the EAP Pattern During
the Pre-Rainy Period of South China 下载免费PDF全文
Based on the NCEP DOE AMIP II daily reanalysis data (1979{2005), the evolution of the East Asia/Pacific(EAP) teleconnection pattern during the pre-rainy period of South China is studied on the medium-range time scale. It is found that positive and negative EAP patterns share a similar generation process. In the middle and upper troposphere, Rossby wave packets emanating from the northeast Atlantic or Europe propagate toward East Asia along the Eurasian continent waveguide and finally give rise to the three anomaly centers of the EAP pattern over East Asia. Among the three anomaly centers, the western Pacific subtropical center appears the latest. Rossby wave packets propagate from the high latitude anomaly center toward the mid-latitude and the subtropical ones. The enhancement and maintenance of the subtropical anomaly center is closely associated with the subtropical jet waveguide and the incoming Rossby wave packets from the upstream. In the lower troposphere, Rossby wave packets emanate from the subtropical Asia toward East Asia.
Positive and negative EAP patterns could not be regarded as "mirrors" to each other with simply re-
versed phase. For the positive pattern, the positive height anomaly center around the Scandinavia Peninsula keeps its strength and position during the mature period, and the Rossby wave packets thus propagate persistently toward East Asia, facilitating a longer mature time of the positive pattern. As for the formation of the negative EAP pattern, however, the incoming Rossby wave energy from the upstream contributes to both the enhancement and southeastward movement of the negative anomaly belt from the Yenisei River to the Bering Strait and the positive anomaly center around Mongolia. At the peak time, the two anomlous circulations are evolved into the Northeast Asia and the mid-latitude anomaly centers of the negative pattern, respectively. The energy dispersion of Rossby wave packets is relatively fast due to the predominant zonal circulation in the extratropics, causing a shorter mature period of the negative pattern.
During the pre-rainy period of South China, the prevalence of the EAP pattern signiˉcantly affects the rainfall over the region south of the Yangtze River. The positive (negative) EAP pattern tends to causepositive (negative) precipitation anomalies in that region. This is di?erent from the earlier research findingsbased on monthly mean data. 相似文献
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The relationship between the intensity of the South China Sea summer monsoon (SCSSM) and
the Nino3.4 index and anomalous atmospheric circulation patterns associated with a strong and weak
SCSSM are investigated using the NCEP/NCAR reanalysis data, Extended Reconstructed Sea Surface
Temperature (ERSST) data and Climate Prediction Center Merged Analysis of Precipitation (CMAP) data.
The SCSSM is significantly positively correlated with the Nino3.4 index in the succeeding northern
autumn and winter. In the strong minus weak SCSSM composite, a positive East Asia-Pacific
teleconnection (EAP) pattern and a negative Europe-Asian-Pacific teleconnection (EUP) pattern appear in
the 500 hPa height difference field; low-level cross-equatorial flows are strengthened over the Maritime
Continent (MC) region; positive (negative) precipitation anomalies occur in the South China Sea and
western north Pacific (MC). A possible mechanism through which SCSSM affects ENSO is proposed. A
strong (weak) SCSSM strengthens (weakens) cross-equatorial flows over the MC. The anomalous
cross-equatorial flows cool (warm) the SST around the MC through enhanced (reduced) surface latent heat
fluxes. The cooling (warming) further leads to suppressed (enhanced) convection over the MC, and causes
the anomalous westerly (easterly) in the equatorial western Pacific, which favors the onset of El Ni?o (La
Ni?a) through modulating the positive air-sea feedback process. 相似文献
350.
华南秋季蒸发量的时空演变特征 总被引:4,自引:0,他引:4
利用华南区域66个气象站点1960~2004年的观测数据分析了华南秋季蒸发皿蒸发量和实际蒸发量的时空变化.分析结果表明:华南中部和西北部是华南秋季蒸发皿蒸发量的两个主要气候变异中心区,华南中部秋季蒸发皿蒸发量具有以年代际变化为主的特征,并且在45年内总体上呈下降趋势.在影响蒸发皿蒸发量的因子中,太阳辐射与蒸发皿蒸发量的相关性最好,呈显著的正相关.对实际蒸发量而言,华南中部和西部偏西地区则是两个主要的变异中心,两区域的秋季实际蒸发量具有以年际变化为主的特征,降水对华南秋季实际蒸发量的影响最为显著,华南秋季实际蒸发量一般都在蒸发皿蒸发量的40%左右,并且比值总体上呈现微弱的由南向北递增趋势. 相似文献