基于城市环境气候图的宁波大气环境分析与调控对策

城市化的蓬勃发展改变了城市气候和环境,产生了诸多气候环境问题,需要有效的城市气候环境信息与调控对策来应对和缓解,城市环境气候图在城市气候环境的规划与调控方面提供了重要指导。在传统城市气候图的基础上,提出了多季节、多环境要素相结合的城市环境气候图构建方法。在此基础上,以具有复杂下垫面和明显季节性气候特征的宁波市区为案例,综合运用遥感反演、GIS空间分析、中尺度数值模拟等技术手段,对城市热负荷、大气污染、通风潜力和风场及整体的城市气候环境进行多季节分析与评估。结果表明:在形成城市气候环境的主要要素方面,城市热负荷、大气污染物分布都具有显著的季节性和空间性差异,宁波市春、夏季同时受热负荷和大气污染影响,冬季仅受大气污染影响,秋季受二者影响均较小;通风潜力的空间格局各季节之间具有高度的相似性;风环境复杂多变,呈现出显著的季节性和空间性差异。对城市气候环境的整体分析发现,城市气候环境高价值区和中价值区主要分布于山林、农田和水体,高风险区位于北仑、镇海和杭州湾南岸的沿海重化工业带,中风险区分布于江北区东部、鄞州城区东西两翼、慈溪城区和奉化城区东北部等工厂厂房密集的区域。进一步在前述分析的基础上,提出了城市风道规划方案和气候环境调控对策,包括2条一级风道、5条二级风道、3条受海陆风影响的三级双向风道、12条受海陆风影响的三级单向风道、13条受山谷风影响的三级单向风道和七类城市气候环境调控对策。提出的多季节、多环境要素相结合的城市环境气候图构建方法适用于季风气候地区复杂气候环境的分析与评估研究,能够提高城市气候环境分析的综合性和准确性,并能够通过风道规划及相关调控对策的制定和实施改善城市热负荷和大气环境质量,缓解各季节的城市气候环境问题,为城市环保、气象、规划等部门提供重要的决策支持,从而促进城市可持续发展和生态城市建设。

Ningbo atmospheric environment analysis and regulating countermeasure based on Urban Climatic Map

Rapid urbanization has changed the urban climate and environment. As a result, many climatic and environmental problems have emerged. Valid urban climatic environment analysis and regulating countermeasures are required in order to cope with and mitigate these issues. An urban climatic map provides important guidance for the planning and regulation of the urban climatic environment. Based on a traditional urban climatic map, this research proposes a new method of building an urban climatic map that considers all seasons and multiple environmental elements. The urban area in Ningbo City, with its complicated underlying surfaces and obvious seasonal climate characteristics, was used as a case study. The technical means, including remote-sensing inversion, spatial analysis of geographical information system (GIS), and mesoscale numerical model simulation, were comprehensively applied to conduct a multi-season analysis and evaluation of the urban thermal load, air pollution, ventilation potential, wind field, and overall urban climatic environment. The results indicate that the spatial distribution of the urban thermal load and air pollutants is characterized by significant seasonal and spatial differences in the principal elements of the formation of an urban climatic environment. Ningbo City is affected by both thermal load and air pollution in spring and summer, affected only by air pollution in the winter, and only slightly affected by both thermal load and air pollution in the autumn. The spatial patterns of ventilation potential are similar in all seasons. Remarkable seasonal and spatial differences are presented, as the wind environment is complex and subject to change. By conducting an overall analysis on urban climatic environments, we found that areas with high and middle values of urban climatic environment are mainly distributed in forests, croplands, and water bodies. Areas with a high risk of urban climatic environment are located in the heavy chemical industrial zones along the coast of Beilun District, Zhenhai District, as well as the southern part of Hangzhou Bay. Areas with an intermediate risk of urban climatic environments are found in the regions where large amounts of industrial factories are clustered, such as the eastern Jiangbei District, eastern and western sides of Yinzhou District, Cixi urban area, and northeast part of the Fenghua urban area. Based on the above analysis, the planning schemes of urban ventilation channels and the regulating countermeasures of climatic environments are further proposed. These include two first-class ventilation channels, five second-class ventilation channels, three third-class bidirectional ventilation channels which are impacted by land-sea breezes, twelve third-class unidirectional ventilation channels which are impacted by land-sea breezes, thirteen third-class unidirectional ventilation channels which are impacted by mountain-valley breezes, and seven types of countermeasures for urban climatic environment regulation. The method of building an urban climatic map considering all seasons and multiple environmental factors raised by this research is applicable to the analysis and evaluation research of the monsoon climate zones with complicated climatic environments. It may also improve urban thermal load and atmospheric environmental quality and ease the problems of urban climatic environments in all seasons. It may do so through ventilation channel planning and formulating and implementing relevant regulatory countermeasures so as to provide support for urban environmental protection, meteorological and planning departments, and promote sustainable urban development and the construction of an ecological city.