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<正>废旧电池、电子废弃物、塑料包装物等废弃物资,是放错位置的"资源"。"资源有限、循环无限"。因此,废弃资源再生利用被人形象地喻为挖掘"城市矿产"。作为全国首批26个再生资源体系建设试点城市之一,合肥按照"政府积极引导,社区作为载体,市场机制运作"原则,引导再生资源行业健康可持续发展,深耕"城市矿产"。从废旧物资中寻找"富矿"以废旧电视机为例,废旧零件通过深加工可以获取各种"矿 相似文献
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大气边界层及其与自由大气之间的相互作用具有明显的非线性特征,而这些特征是经典Ekman理论所不能描述的,因此,发展中等复杂程度(介于完全模式与经典Ekman模型之间)的大气边界层动力学模式,简称中间模式,对人们从理论上认识大气边界层动力学过程的非线性特征具有重要意义。本文对目前最具代表性的几个中间边界层模型:地转动量近似边界层模型、Ekman动量近似边界层模型以及弱非线性边界层模型进行了总结和分析,阐述了Ekman层主要动力学特征。通过分析上述各模型的理论框架,揭示了各模型的物理意义及其在描述Ekman边界层基本动力特征上的优点和局限性,并指出尽管在细节定量描述上有差异,但各中间模型对Ekman层动力学特征的定性描述具有很好的一致性。对于这些Ekman边界层近似理论模型的进一步应用问题,主要回顾和总结了利用上述模型探讨地形边界层结构、大气锋生过程、低层锋面结构和环流以及边界层日变化、低空急流形成等动力学问题的研究,并对这些研究所揭示的Ekman层动力学特征及其对自由大气低层运动的影响进行了分析,结果表明,这些Ekman边界层近似模型可以较好地揭示大气边界层动力学特征,在大气边界层动力学及其与自由大气相互作用的研究上具有重要价值。另外,还对目前Ekman边界层理论研究中存在的问题进行了一些分析,提出了有待进一步研究的科学问题。 相似文献
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在真三轴试验基础上揭示了多种不同结构性原状黄土的强度变化规律,分析了在岩土工程实践中常用的Mohr-Coulomb准则和Matsuoka-Nakai准则对不同结构性原状黄土的适应性。结果表明:当结构性黄土的强度越大时,其在π平面上的破坏线越接近于抹圆曲边三角形,反之其在π平面上的破坏线越接近于抹圆角三角形;结构性黄土随着结构性的增大在π平面上的强度破坏线从抹圆角三角形逐渐向抹圆曲边三角形发展,最终趋近于Mises圆;两个强度准则所描述的强度都比结构性原状黄土的实际强度值小,Mohr-Coulomb准则的误差比Matsuoka-Nakai准则的误差大,并且随着结构性的增强其误差也逐渐增大。 相似文献
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In this study,the effect of vertical wind shear(VWS)on the intensification of tropical cyclone(TC)is investigated via the numerical simulations.Results indicate that weak shear tends to facilitate the development of TC while strong shear appears to inhibit the intensification of TC.As the VWS is imposed on the TC,the vortex of the cyclone tends to tilt vertically and significantly in the upper troposphere.Consequently,the upward motion is considerably enhanced in the downshear side of the storm center and correspondingly,the low-to mid-level potential temperature decreases under the effect of adiabatic cooling,which leads to the increase of the low-to mid-level static instability and relative humidity and then facilitates the burst of convection.In the case of weak shear,the vertical tilting of the vortex is weak and the increase of ascent,static instability and relative humidity occur in the area close to the TC center.Therefore,active convection happens in the TC center region and facilitates the enhancement of vorticity in the inner core region and then the intensification of TC.In contrast,due to strong VWS,the increase of the ascent,static instability and relative humidity induced by the vertical tilting mainly appear in the outer region of TC in the case with stronger shear,and the convection in the inner-core area of TC is rather weak and convective activity mainly happens in the outer-region of the TC.Therefore,the development of a warm core is inhibited and then the intensification of TC is delayed.Different from previous numerical results obtained by imposing VWS suddenly to a strong TC,the simulation performed in this work shows that,even when the VWS is as strong as 12 m s-1,the tropical storm can still experience rapid intensification and finally develop into a strong tropical cyclone after a relatively long period of adjustment.It is found that the convection plays an important role in the adjusting period.On one hand,the convection leads to the horizontal convergence of the low-level vorticity flux and therefore leads to the enhancement of the low-level vorticity in the inner-core area of the cyclone.On the other hand,the active ascent accompanying the convection tends to transport the low-level vorticity to the middle levels.The enhanced vorticity in the lower to middle troposphere strengths the interaction between the low-and mid-level cyclonical circulation and the upper-level circulation deviated from the storm center under the effect of VWS.As a result,the vertical tilting of the vortex is considerably decreased,and then the cyclone starts to develop rapidly. 相似文献
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With the Weather Research and Forecasting model (WRFV3.2.1), the application of spectrum nudging techniques in numerical simulation of the genesis and development of typhoon Longwang (2005) is evaluated in this work via four numerical experiments with different nudging techniques. It is found that, due to the ability to capture the large-scale fields and to keep the meso-to small-scale features derived from the model dynamics, the experiment with spectrum nudging technique can simulate the formation, intensification and motion of Longwang properly. The improvement on the numerical simulation of Longwang induced by the spectrum nudging depends on the nudging coefficients. A weak spectrum nudging does not make significant improvement on the simulation of Longwang. Although the experiment with four-dimensional data assimilation, i.e., FDDA, also derives the genesis and movement of Longwang appropriately, it fails to simulate the intensifying process of Longwang properly. The reason is that, as the large-scale features derived from the model are nudged to the observational data, the meso- to small-processes produced by the model dynamics important to the intensification of typhoon are nearly smoothed by FDDA. 相似文献
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一次梅雨期台风远距离暴雨的分析研究 总被引：3，自引：2，他引：1
用NCEP 1°×1°再分析资料、MICAPS系统地面站资料、TRMM卫星降水资料以及自动站雨量资料分析了2011年梅雨后期发生在江苏省南京市的一次暴雨过程。结果表明:此次暴雨发生在中高层高空深槽前部、低空切变线附近、低层低涡和地面低压的东北部,是西风带低值系统及其引导的低层低涡与西进北上的"马鞍"台风共同作用产生的。925 h Pa上中国东南沿海位于低层低涡东北部的东南偏东气流影响下,将来自于西太平洋的水汽源源不断向暴雨区输送,为暴雨的发生提供了良好的水汽条件。不仅如此,此东南偏东气流还使得华南和东南沿海地区暖平流明显。低层暖平流输送伴随的小幅增温和水汽输送导致的湿度层增厚,导致南京附近大气层结不稳定是暴雨发生的热力环境。随着"马鞍"台风的西进北上,其北侧副高中的干空气逐渐被卷至中国东南沿海附近,与大陆上的暖湿气流形成明显对比,形成了一条明显的能量锋。与此同时,在长江中游地区,残余的梅雨锋也表现为一条能量锋,两条能量锋在南京附近相接,造成明显的上升运动,从而触发了暴雨的发生。 相似文献
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Comparison of the multi-scale features in two persistent heavy rainfall events in the middle and lower reaches of Yangtze River 
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下载免费PDF全文 Two persistent heavy rainfall(PHR) events in the middle and lower reaches of Yangtze River(MLYR)occurring in June 1982 and 1998 are studied in this paper.Though both events happened in the Meiyu season,their large-scale background and developing processes were quite different.During the PHR event in 1982,the Lake Baikal area was occupied by a strong westerly trough and the western Pacific subtropical high(WPSH) was stronger and more westward-extending than the normal years.Under such a condition,the cold dry air and warm moist air were continuously transported to the MLYR and favored the PHR there.For the event in 1998,the WPSH was similar to that in 1982,while the westerly trough in the Lake Baikal area was comparatively weak and a shortwave trough situating in East China contributed to advect cold dry air to the MLYR.It is found that the high-latitude trough was closely related to the 1030-day low-frequency oscillation while the anomaly of WPSH was linked with the combined effect of both30 60- and 10 30-day low-frequency oscillations in the PHR event in 1982.By contrast,the 60-day low-pass perturbation demonstrated positive impact on the westward extension of WPSH and development of the Baikal trough while the 30 60-day oscillation played a role in strengthening the shortwave trough in East China and the WPSH in the case of 1998.Though the low-latitude 30 60-day oscillations contributed to the intensification and westward extension of the WPSH in both PHR events,their evolution exhibited evident differences.In the 1982 case,the 30 60-day anomalies originated from the western Indian Ocean were much more like the Madden Julian Oscillation,while its counterpart in the 1998 case was much more similar to the first mode of the boreal summer intraseasonal oscillation. 相似文献
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To investigate the multi-scale features in two persistent heavy rainfall (PHR) events in the middle and lower reaches of the Yangtze River (MLRYR) in June of 1982 and 1998, this study examines the impact of multi-scale oscillations in the north and south of 30°N on the PHR events by performing sensitivity experiments with the Weather Research and Forecast (WRF) model. It is found that the 60-day lowpass perturbation made a trivial contribution to the MLRYR precipitation during the PHR event in 1982. This PHR event resulted mainly from the combined effects of 30–60-day oscillation at low latitudes and 10–30-day oscillation at both high and low latitudes. The southwesterly anomalies associated with the 30–60-day anticyclonic anomaly over the northwestern Pacific facilitated moisture transport from the ocean to the MLRYR and enhanced the low-level convergence and ascending motion in the MLRYR. This similarly occurred in the 10–30-day oscillation as well. Moreover, the 10–30-day anomalies at high latitudes played a role in strengthening the large-scale low-level convergence over the MLRYR. The PHR event in 1998 was mainly related to the 60-day oscillation at both high and low latitudes and 30–60-day oscillation at low latitudes. The 60-day low-pass filtered anomalous cyclone at high latitudes in the north of 30°N contributed to the development of low-level convergence and ascending motion in northern MLRYR while the anomalous anticyclone at low latitudes in the south of 30°N not only increased the moisture in the MLRYR but also preconditioned the dynamical factors favorable for PHR over the whole area. The 30–60-day perturbations located north and south of 30°N worked together producing positive moisture anomaly in the MLRYR. In addition, the anomalous circulation in the south of 30°N tended to favor the development of ascending motion and low-level convergence in the MLRYR. 相似文献
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P—σ混合坐标原始方程模式的改进和试验 总被引：2，自引：3，他引：2
在五层Ｐ－σ混合坐标原始方程模式的基础上，改进成了一个九层Ｐ－σ混合坐标原始方程模式。模为１７×３９个格点，分辨率为５°×５°，其物理过程与五层模式相同。该模式性能稳定，用该模式对１９９４年冬的一次寒潮过程进行了模拟，温压场的主要特征符合实况。 相似文献