【作者】 张叶；

【导师】 陈海山；

【作者基本信息】 南京信息工程大学 ， 气象学， 2012， 硕士

【摘要】 本文采用包含陆面模式NCAR CLM4.0和城市冠层参数化方案的大气环流模式NCAR CAM4.0,设计敏感性试验(将中国东部沿海一半的区域变为城市),通过对比敏感性试验与控制试验的差异,探讨中国东部大规模城市化对东亚季风及我国气候的可能影响,本研究是针对大规模城市化影响问题和城市化大尺度气候效应问题的尝试性研究,研究结果可以为更深入理解城市化的影响及其机理提供重要的物理依据,得到的主要结论如下：(1)中国东部的大规模城市化过程,使得我国东部区域的地表温度、气温均出现大范围的显著增暖,但不同月份、不同季节的响应程度不同。地表温度增暖现象最为明显,冬季及夏季地表温度最大升温幅度分别可达2.80℃和3℃；气温的增暖幅度低于地表温度的增暖幅度,并且冬季的增暖程度要高于夏季,分别为2.5℃和2.25℃；冬、夏日最低气温和日最高气温也均明显升高,其中冬季日最低温度的增温幅度要显著高于日最高温度,夏季与之相反;与此同时,城市热岛强度也发生了较明显的变化,而且冬季的热岛强度要低于夏季,冬、夏城乡最高温差可达0.36℃和0.4℃。(2)我国东部区域的地表能量平衡发生了显著变化,响应程度的高低是随时间变化的。冬、夏地表向上的净长波辐射和地表感热通量热均明显增强,而地表短波辐射的变化则相对较小,潜热通量在夏季显著减少而冬季变化不明显；由大规模城市化导致的地表能量平衡的变化,明显加强了地表对大气的加热。(3)地表能量平衡的变化及地表对大气的加热异常,能够对东亚季风环流产生显著的影响。我国东部大规模城市化,总体上将增强初夏6月份的季风,但会减弱7、8月份的夏季风,而东亚冬季风强度将减弱,但冬季我国东北地区的冬季风表现出区域性的异常增强,总体而言,城市化对东亚季风环流的显著影响主要出现在中低层。(4)对降水而言,中国东部的大规模城市化,会使得6月份我国北部降水增加南部降水减少,7月份东北至华北北部降水增加、华北南部至黄淮流域降水减少、长江中下游至华南降水增加,8月份北部降水减少南部降水增加；对我国降水雨带而言,大规模城市化会使得华南前汛期降水减少,江淮梅雨期降水减少,华北和东北雨季降水减少。(5)就季节演变而言,我国东部大规模城市化将导致南海北部夏季风爆发推迟2候,而撤退推迟2候,但不会影响南海季风的持续时间,对其他地区而言,城市化会对夏季风的爆发和撤退影响不大,只是影响其强度;大规模城市化的影响在不同季节是各不相同的。更多还原

【Abstract】 By using the global atmospheric circulation model CAM4.0including the Community Land Model CLM4.0and urban canopy parameterization scheme, the possible impacts of large-scale urbanization over eastern China on East Asian monsoon and China climate was investigated via idealized experiments (turning half of regions in the eastern China to urban). This study is an attempt for the studying of the effects of large-scale urbanization and the large-scale effects of urbanization. The main conclusions are as follows:(1) The massive urbanization process over the eastern China lead the land surface temperature and the air temperature over that region to warm significantly, but the responses differ from one time to another. The surface temperature increases most evidently, and the warming amplitudes are2.8℃in winter and3℃in summer; Regarding to the amplitude of warming, the air temperature is smaller than the surface temperature, and in winter is2.5℃but2.25℃in summer; The daily minimum temperature and maximum temperature also rise significantly in winter and summer, and the warming of the daily minimum temperature is more obvious than daily maximum temperature in summer, but in winter the result is opposite; Meanwhile, the urban heat island also changes a lot, and the strength of the urban heat island is0.4℃in winter but0.36℃in summer.(2) Significant changes in the surface energy balance occur over eastern region of China, and the strength differs from time. The net upward long-wave radiation and surface sensible heat flux in winter and summer are markedly enhanced, while the changes of the net surface shortwave radiation are relatively small, the latent heat flux decline significantly in summer but don’t change much in winter; Changes in the energy balance over surface caused by the massive urbanization significantly enhance the surface heating to the atmosphere.(3) Changes in the energy balance over the surface and the abnormal heating from surface to the atmosphere have a large impact on the East Asian monsoon circulation. The large-scale urbanization in the eastern China, will enhance the monsoon in June but weaken the summer monsoon in July and August, while the East Asian winter monsoon will be weakened, but in the Northeast China the East Asian monsoon is enhanced in winter. Overall, the significant effects of urbanization on the East Asian monsoon circulation are mainly in the middle and low level.(4)With the extensive urbanization in the eastern China, the precipitation will increase in the northern China but reduce in the southern China in June. Form the Northeast China to the northern part of the North China the rainfall increases, and from Huanghuai Valley to the southern part of the North China the rain reduces, but in the middle and lower reaches of the Yangtze River to the South China the rainfall increases in July. In August the precipitation reduces in the North but increases in the South. For the rainbelt, the precipitation decreases in the rainy season in South China, in the rainy season in the Yangtze and Huaihe Valleys or in the rainy season in North China and Northeast China.(5)In relation to the seasonal evolution, the massive urbanization in the eastern China will delay the onset of the summer monsoon for2pentad in the north part of the South China Sea, but postpone the withdrawal for2pentad, so the cycle of the summer monsoon don’t change over the northern part of South China Sea. But for other regions, the urbanization doesn’t affect the outbreak and the withdrawal of the summer monsoon and only affect its strength. The impacts of the large-scale urbanization differ from season.更多还原