【作者】 张芳；

【导师】 闵锦忠；

【作者基本信息】 南京信息工程大学 ， 气象学， 2012， 硕士

【摘要】 城市化改变了局地的动力学和热力学特征,对降水天气现象必定有一定的影响。本文主要采用江苏省基本站资料、FNL再分析风场资料及人口、土地、夜间灯光数据,利用一个城市化指数,分析了城市化对降水特征的影响以及城市不同发展阶段降水的变化。主要结果如下：(1)江苏省城市化指数分布表征的城市群类型与人口、土地及灯光数据分析的结果一致：即苏南内陆以宁镇扬、苏锡常为主的城市化程度很高的地区、苏北内陆以徐州为主的城市化程度较高的地区、沿海城市化程度较低的地区。因此,该指数在表征城市化程度上具有一定的准确性,并且考虑了城市气温和水汽对城市气候效应的综合响应,比起人口、土地、夜间灯光等指标更能客观反映城乡之间物理特性的差异。(2)近似弱气流背景下,降水事件的日变化特征显示午后和傍晚的降水事件发生概率较大。季节变化为降水事件主要发生在夏季。这一结果可能夸大了中尺度系统的作用;(3)降水量集中因子分析表明：西南风控制下降水增加最多;西风和西南风在城市的北部和东北部形成降水高值区,位于城市的下风方。值得注意的是,南风和西南风引导气流下均存在一定的“上游效应”,说明城市化降水效应的影响机制具有一定的复杂性,需要进行高水平数值模拟来研究这一问题。(4)全天的降水量累积距平近40年变化趋势变化幅度大小依次为苏南内陆城市化程度最高的地区、沿海城市化程度最低地区、苏北内陆城市化程度较高的地区。苏北内陆地区的降水量变化趋势主要体现在白天,沿海地区夜间降水量变化幅度略高于白天,而苏南内陆地夜间降水量对全天降水量的贡献更为重要。(5)城市发展快速期和缓慢期不同区域对比显示,年降水量差异、夏季降水量差异以及小雨、中雨、大雨和暴雨雨日数的差异由大到小依次为苏南内陆城市化程度最高的地区、沿海城市化程度最低的地区、苏北内陆城市化程度较高的地区。可见,城市化降水效应已经由单个城市逐渐扩展到城市群、带,区域性特点日益明显。(6)在城市发展缓慢期,苏北内陆地区以农村、小城镇为主,城市较少,规模也比较小,随着社会经济的发展,小城镇不断崛起,大城市不断扩张,在这一形态转变过程中,对局地的降水极有可能产生比其他区域更为重要的影响。更多还原

【Abstract】 Urbanization has changed the local dynamics and thermodynamics features, which must have a certain effect on rainfall. Based on a more objective urbanization index, the basic station data in Jiangsu Province, FNL reanalysis wind field data and population, land, the night light data were used to analyse the influence of urbanization on the characteristics of precipitation and the rainfall changes during the different development phase of the cities. The main results are as follows:Urbanization index distribution in Jiangsu Province has the obvious regional characteristics, consistent with thef urban agglomeration types revealed by population, land and lighting data. That is the southern inland of a high degree of urbanization, northern inland of a second degree of urbanization and coastal areas of a lower degree of urbanization. Therefore, this index is of certain accuracy to describe the characteristics of the urbanization and considers the integrated response of temperature and water vapor to urban climate effect Compared to the population, land and the night lights, this index can more ocjectively reflect the physical difference between urban and rural areas.In a approximately weak synoptic flow,most of the precipitation events occurred between afternoon and toward evening. Also, the precipitation days showed a maximum during summer.The results may show a larger fraction of nocturnal events.The rainfall consatration factor analysis revealed that the SW flows yield the greatest rainfall amounts. The W and SW flows produced high mean daily rainfall totals in the N and NE cells, where the urban anomaly apparently maximizes and is climatologically downwind of the nanjing city. It should be noted that the S and SW flows were associated with an "upwind" anomaly, indicating that the complex of urban rainfall effect. Modeling work is still needed to determine which urban factors are most important for altering rainfall.Accumulated precipitation anomaly of a full day analysis revealed that the sizes of the variation trend nearly40years were ranged from southern Jiangsu inland areas of the most urbanized, coastal areas of lowest urbanization, northern Jiangsu inland areas of higher urbanization. The trend of precipitation mainly embodied in the daytime in northern Jiangsu inland areas. In the coastal areas, the rate of changes in rainfall was slightly higher at night than during the day. at night In southern Jiangsu inland areas, the contribution of night rainfall precipitation is much more important than that during the daytime. Compared between the slowly and rapidly developed period of cities, the difference of yearly rainfall, summer rainfall, days of light rain, moderate rain, heavy rain and storm rain was ranged from southern Jiangsu inland areas of the most urbanized, coastal areas of lowest urbanization, northern Jiangsu inland areas of higher urbanization. Visibly, urbanization precipitation effects have been performed by a single city expanding gradually to the urban agglomeration or belt. Regional characteristics are more and more obvious.During the slowly developed period of cities, counties and towns were major parts of northern Jiangsu inland areas. With the development of society, counties and towns were gradually expanded and big cities were spreaded day by day. This transformation may has a more important impact on local precipitation in this areas.更多还原