排序方式： 共有25条查询结果，搜索用时 187 毫秒
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Ralf Döscher Klaus Wyser H. E. Markus Meier Minwei Qian René Redler 《Climate Dynamics》2010,34(7-8):1157-1176
The relative importance of regional processes inside the Arctic climate system and the large scale atmospheric circulation for Arctic interannual climate variability has been estimated with the help of a regional Arctic coupled ocean-ice-atmosphere model. The study focuses on sea ice and surface climate during the 1980s and 1990s. Simulations agree reasonably well with observations. Correlations between the winter North Atlantic Oscillation index and the summer Arctic sea ice thickness and summer sea ice extent are found. Spread of sea ice extent within an ensemble of model runs can be associated with a surface pressure gradient between the Nordic Seas and the Kara Sea. Trends in the sea ice thickness field are widely significant and can formally be attributed to large scale forcing outside the Arctic model domain. Concerning predictability, results indicate that the variability generated by the external forcing is more important in most regions than the internally generated variability. However, both are in the same order of magnitude. Local areas such as the Northern Greenland coast together with Fram Straits and parts of the Greenland Sea show a strong importance of internally generated variability, which is associated with wind direction variability due to interaction with atmospheric dynamics on the Greenland ice sheet. High predictability of sea ice extent is supported by north-easterly winds from the Arctic Ocean to Scandinavia. 相似文献
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Sea-ice cover over the Hudson Bay (HB) exhibits large variability in the freeze-up season normally starting in November. Its influence on the climate over eastern Canada has been studied with the Canadian Regional Climate Model (CRCM) in three steps. First, a 30-year continuous simulation from 1970 to 1999 was performed as a control run to evaluate the simulated climate variability over eastern Canada, in particularly variability associated with the North Atlantic oscillation (NAO). Then, 50 additional 1 month experiments were performed with modified sea-surface conditions prescribed over the HB. These integrations allowed us to quantify the contribution of HB sea-ice anomalies versus large scale NAO atmospheric variability (as defined by prescribed lateral boundary conditions) in inducing climate variability over eastern Canada. Results show that the NAO is the dominant factor controlling climate variability over eastern Canada. The contribution of HB sea-ice anomalies is significant only in the immediate coastal region. Under the influence of different phases of NAO, HB sea-ice anomalies do co-vary with temperature and precipitation anomalies downstream of the HB over eastern Canada. The ultimate cause of this co-variability is NAO variability which forces variability in both HB sea-ice cover as well as temperature/precipitation over eastern Canada. 相似文献
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基于2009~2010年国家、区域测震台网的387个宽频带台站数据,通过互相关方法提取到可靠的瑞利波经验格林函数,利用相位匹配滤波时频分析技术测量瑞利波相速度频散曲线,最后采用噪声层析成像方法获得了华南地区不同周期的瑞利波相速度分布图。结果显示,华南地区速度结构横向变化幅度较小,反映了华南地区作为一个整体较为稳定,与华南地区自晚中生代以来未发生过强烈构造活动的特征基本一致;虽然华南地区整个岩石圈速度结构较为均匀,但扬子块体西部、四川盆地与扬子块体东部、华夏块体间存在明显的速度差异,体现在周期为8~10s时华夏块体相速度大于扬子块体西部、川滇块体以及四川盆地,由于沉积层较厚四川盆地速度最低;周期为10~30s时华夏块体面波相速度大于扬子块体西部和四川盆地,而川滇块体速度最低;周期为35s时扬子块体、华夏块体、四川盆地的速度基本一致,且高于川滇块体,这与华南地区地壳厚度明显小于川滇块体的特征相符。 相似文献
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长江上空辐射雾的数值研究 总被引：18，自引：6，他引：18
为研究长江上空辐射雾的形成和发展与长江水面和长江两岸复杂地形的关系,我们设计了一个二维辐射雾的数值模式,模式包含大气长波辐射冷却、地表能量收支、液态水的重力沉降等影响雾的形成和发展的主要因子。 结果表明:长江两岸的地形和长江水面对雾的形成和发展影响较大,若在长江河道较宽且配有合适的地形地区,长江上空的雾可发展到一个较高的高度,而在长江两岸地形较陡的地区,雾有可能就不出现。长江水面的宽窄直接影响着雾的深浅。 相似文献
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矿区水文地质研究进展及中长期发展方向 总被引：2，自引：0，他引：2
矿区水资源保护和矿山防治水这两个互相矛盾又紧密联系的问题给传统的矿山水文地质学带来了更多的挑战和机遇,迫切需要新理论、新技术的发展。为了更好的实现矿区未来地下水资源的开采、利用与保护以及采煤安全和区域水资源可持续利用,本文选择长治盆地为重点研究区,从采动引起的覆岩移动入手,在资料分析的基础上,采用相似材料模拟、综合物探、野外监测、现场注(压)水试验的方法,运用水文地质学原理研究了采煤引起含水层结构变异厚度及其渗透性变化特征;在此基础上,以长治盆地集中开采区水文地质条件和野外监测数据为基础,建立了区域地下水流场三维动态模拟试验台,为研究含水层结构变异后的地下水循环机理和水资源重新分布提供技术支撑;本文同时指出了我国矿山水文地质研究目前存在的问题和面临的挑战,分析了矿山水文地质学科的发展趋势,展望了未来相关分支学科和关键核心技术的发展方向与前景。 相似文献
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A puff model is developed in this study, which simultaneously considers the Monte-Carlo technique, the time and space changes of atmospheric parameters, multiple continuity pollutant sources, linear chemical trans-formation and removal of pollutants, and the effect of complex terrain. The continuously observed turbulent statistical quantities, Lagrangian time scales, mesoscale flow field, and mixing layer depth in the PBL in the Dianchi area in China are directly put into the model, and the diurnal variations of air pollution are forecasted, which are dominated by such mesoscale local circulations as mountain and valley breeze, land and lake breeze, and city heat island (Kunming City). The results show that in the case of inputting the same data, they are in good agreement with the experimental data, as well as with the results of the three-dimensional advection-diffusion model (TD-ADM); the diurnal variation of mesoscale local circulation results in the obvious diurnal variation of mesoscale concentration distribution patterns; the Dianchi lake (appr. 300 km2) has a considerable effect on the distribution of air pollution in the area. 相似文献
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An alternative approach to determine critical angle of contrast reversal and surface roughness of oil slicks under sunglint 总被引：1，自引：0，他引：1
Yansha Wen Mengqiu Wang Shaojie Sun Minwei Zhang Zhihua Mao 《International Journal of Digital Earth》2018,11(9):972-979
The critical angle is the angle at which the contrast of oil slicks reverse their contrasts against the surrounding oil-free seawater under sunglint. Accurate determination of the critical angle can help estimate surface roughness and refractive index of the oil slicks. Although it’s difficult to determine a certain critical angle, the potential critical angle range help to improve the estimation accuracy. In this study, the angle between the viewing direction and the direction of mirror reflection is used as an indicator for quantifying the critical angle and could be calculated from the solar/viewing geometry from observations of the Moderate Resolution Imaging Spectroradiometer (MODIS). The natural seep oil slicks in the Gulf of Mexico were first delineated using a customized segmentation approach to remove noise and apply a morphological filter. On the basis of the histograms of the brightness values of the delineated oil slicks, the potential range of the critical angle was determined, and then an optimal critical angle between oil slicks and seawater was then determined from statistical and regression analyses in this range. This critical angle corresponds to the best fitting between the modeled and observed surface roughness of seep oil slicks and seawater. 相似文献