环太湖地区城市热岛特征的遥感资料分析与数值模拟研究

发布时间：2018-05-10 18:28

本文选题：城市热岛效应 + 高温过程　；参考：《南京大学》2015年硕士论文

【摘要】：环太湖地区是我国城市化发展水平最高的地区之一,研究其城市化对大气边界层、天气和气候过程的影响对提高城市气象服务水平、城市发展规划有重要的指导作用。本文结合台站资料、卫星遥感观测和WRF模式分析了近十年来环太湖地区城市热岛的时空变化特征,研究了高温过程中的城市热岛效应,探讨了城市化对区域天气、气候的影响。首先,本文基于2003-2013年台站资料分析了环太湖地区城市热岛特征及城市热岛增温率的季节变化和年变化规律。结果表明,参考站的选取对城市热岛研究结果的影响很大,用常熟站和张家港站为参考站得到的城市热岛强度高,其日变化表现为夜高昼低的“凹”字形特征,而以东山站为参考站得到的热岛强度则表现为昼高夜低的日变化特征。尽管近十年来城市增温现象不明显,但城市热岛增温率和城市化增温贡献率研究结果显示,城市热岛近年来仍然有增强的趋势,城市化对区域增温贡献显著。其次,结合台站资料和MODIS卫星遥感观测分析发现,环太湖地区中午不稳定类的天数最多,约占总天数50%,且近十年来呈增加趋势；弱不稳定类和中性类的天数呈减少趋势。在不同稳定条件下测得的城市热岛结果表明,随着白天稳定度由不稳定转变到中性,地表热岛和大气热岛强度均逐渐减弱。夜间地表热岛的研究结果受参考站的影响很大,东山站及常熟站受环境和经济发展影响,地表温度高,以之为参考站得到夜间的地表热岛强度非常弱。若选取张家港站或太湖上风向的郊区为参考站,则能很好地体现地表热岛的季节性差异,即白天表现为春夏高、秋冬弱的特征,夜间表现为春季强、夏季弱的特征。最后,结合观测资料和数值模拟研究了2013年夏季高温过程对城市热岛效应的影响。观测结果显示,2013年夏季高温过程影响范围广,对城市、小城镇和郊区均有显著的增温作用。与往年相比,在白天,郊区气温增加更明显,使城郊温差减小,大气热岛强度减弱；在夜间,城郊温差增大,大气热岛强度会比往年偏高。然而,对地表城市热岛而言,日间的地表热岛较强,略高于往年极不稳定天气条件下的地表热岛强度。进一步的数值模拟研究表明YSU边界层方案对气温、地表温度和相对湿度的模拟结果较好,MYJ边界层方案对风速和比湿的模拟结果略好。模式虽能较准确地模拟高温期间的气温变化趋势,但会低估气温,高估相对湿度。各参数化方案对地表温度的模拟结果差异也较大。尤其是在夜间,YSU方案对城市地表温度的模拟效果好,对郊区及水体的模拟能力差；MYJ方案模拟水体的表面温度与遥感观测结果相近,但会严重低估城市地表温度。城市三维结构复杂加上模式本身对水汽和风场的模拟能力不足,使得模式对比湿和风速的模拟结果较差。
[Abstract]:The area around Taihu Lake is one of the areas with the highest level of urbanization in China. The study of the influence of urbanization on the atmospheric boundary layer, weather and climate process plays an important guiding role in improving the level of urban meteorological service and urban development planning. Based on the station data, satellite remote sensing observation and WRF model, this paper analyzes the spatial and temporal variation characteristics of urban heat island around Taihu Lake in recent ten years, studies the urban heat island effect in the process of high temperature, and discusses the influence of urbanization on regional weather and climate. Firstly, based on the data of stations from 2003 to 2013, the characteristics of urban heat island in Taihu Lake region and the seasonal and annual variation of urban heat island temperature increase rate are analyzed. The results show that the selection of reference stations has a great influence on the research results of urban heat island. The intensity of urban heat island obtained by Changshu station and Zhangjiagang station is high, and the diurnal variation is "concave" character of high night height and low day. The intensity of heat island obtained from Dongshan station as reference station is characterized by diurnal variation of high day and low night. Although the phenomenon of urban warming is not obvious in recent ten years, the research results of urban heat island warming rate and urbanization warming contribution rate show that the urban heat island still has an increasing trend in recent years, and urbanization contributes significantly to regional warming. Secondly, combined with station data and MODIS satellite remote sensing observation and analysis, it is found that the number of days around Taihu Lake is the most at noon, accounting for about 50 days of the total number of days, and in the last ten years, the number of days of weak unstable class and neutral type is decreasing. The results of urban heat island measured under different stable conditions show that the intensity of surface heat island and atmospheric heat island decrease gradually with the change of day stability from instability to neutrality. The research results of the night surface heat island are greatly affected by the reference station, Dongshan station and Changshu station are affected by the environment and economic development, the surface temperature is high, and the intensity of the surface heat island at night is very weak. If the Zhangjiagang station or the suburb of the wind direction on Taihu Lake is selected as the reference station, the seasonal difference of the surface heat island can be well reflected, that is, the characteristics of spring and summer are high in daytime, weak in autumn and winter, strong in spring and weak in summer at night. Finally, the effects of summer high temperature on the urban heat island effect in the summer of 2013 are studied by means of observational data and numerical simulation. The observation results show that the summer high temperature process in 2013 has a wide range of effects, and has a significant warming effect on cities, small towns and suburbs. Compared with the previous years, the temperature increases more obviously in the suburbs during the day, which decreases the temperature difference in the suburbs and weakens the intensity of the atmospheric heat island, but at night, the intensity of the thermal islands in the suburbs will be higher than that in the previous years. However, for the surface urban heat island, the surface heat island is stronger in daytime, which is slightly higher than the intensity of the surface heat island under the extremely unstable weather conditions in previous years. Further numerical simulation results show that the simulation results of YSU boundary layer scheme for air temperature, surface temperature and relative humidity are better than that of YSU scheme for wind speed and specific humidity. Although the model can accurately simulate the trend of temperature change during high temperature, it will underestimate the temperature and overestimate the relative humidity. The simulation results of various parameterized schemes for surface temperature are also quite different. Especially at night, YSU scheme has good simulation effect on urban surface temperature, and MYJ scheme is similar to remote sensing observation results, but it will seriously underestimate the urban surface temperature. Due to the complex three-dimensional structure of the city and the insufficient ability of the model itself to simulate the water vapor and wind fields, the simulation results of the model compared with the wet and the wind speed are poor.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X16;X87

【参考文献】