西北干旱高辐射城市银川臭氧污染气象条件与光化辐射通量研究

At present, ozone pollution is an environmental problem faced by many cities. Due to dry climate, strong solar radiation, urbanization and emissions from the energy and chemical base, ozone pollution is gradually increased in Yinchuan, the capital of the Ningxia Hui Autonomous Region. The meteorological conditions for ozone formation and the characteristics of its precursors in Yinchuan have significant differences with other cities, it is essential to control ozone pollution according to local conditions. Through data analysis combined with numerical simulation, the temporal and spatial variation, the pollution characteristics and the transport-proliferation laws of ozone in Yinchuan will be analyzed in this project, and the in-depth study on the characteristics of actinic radiation flux which drives photochemical reaction and ozone formation will be conducted as well. At the same time, the representative cities of typical climatic zones in China, such as Beijing, Guangzhou, Nanjing, Chengdu and Shenyang, will be selected to study the similarities and differences between the meteorological conditions and the photochemical radiation characteristics of ozone pollution in Yinchuan and in other cities, to explore the uniqueness of ozone pollution in Yinchuan. The relationship between the actinic radiation flux and the concentrations of ozone and its precursors during the ozone pollution process will be simulated by Models-3/CMAQ model coupled with TUV, explaining the mechanism and transport conditions for ozone pollution in Yinchuan area. This study helps to clarify the understanding of the meteorological conditions that have an important impact on ozone generation. It is of great significance for the industrial layout, urban planning and air pollution control of other similar cities in the western region under the situation of rapid urbanization.

目前，近地面臭氧污染是许多城市面临的大气环境问题。宁夏银川市气候干燥、太阳辐射强烈，受城市化及能源化工基地污染排放影响，臭氧污染逐步加重。银川臭氧生成的气象条件及前体物特征与其它城市有明显差异，因地制宜、科学精准进行治理至关重要。本项目拟通过资料分析结合数值模拟，分析银川市臭氧时空变化规律、污染特点及传输扩散规律，深入研究驱动光化学反应与臭氧生成的光化辐射通量特征；同时选取我国典型气候区代表性城市北京、广州、南京、成都和沈阳，研究银川臭氧污染气象条件及光化辐射特征与这些城市的异同，探究其独特性；并耦合TUV与Models-3/CMAQ模型，模拟研究臭氧污染过程期间光化辐射通量与臭氧及前体物的浓度状况，解释银川地区臭氧污染形成机理及输送状况。本研究有助于厘清对臭氧生成有重要影响的关键气象条件的认识，对于快速城镇化形势下的西部其他类似城市的工业布局、城市规划和空气污染治理具有借鉴意义。

近地层臭氧不仅受前体物影响，而且与气象因素密切相关，光化辐射作为大气光化学反应的驱动力，是影响对流层臭氧生消的关键因素。项目分析了银川市臭氧变化规律及污染气象条件，模拟研究了光化辐射通量特征及影响因子，比较了银川与其他气候背景区代表性城市的异同。2015-2020年银川市臭氧多年平均值为154µg·m-3，呈先增加后减小的趋势，2017、2018年最高，2015年最低，6月最高，12月最低，小时浓度8时最小，16时最大，清洁对照点贺兰山马莲口臭氧浓度最大，学院路次之，贺兰山东路再次。臭氧受气温影响最大，其次是辐射，再次是相对湿度，受贺兰山地形阻挡及周边工业园区影响，偏南、偏东风有利于银川臭氧浓度上升；易引发臭氧污染的环流形势有槽脊型、宽广低槽型、副高型和东北高脊型，最主要输送路径为东南气流。代表性城市臭氧年际变化、日变化、城区与郊区差异及与前体物关系等受气候背景差异影响较小，但月变化及与气象要素关系差别较大，广州为近似三峰型，成都南京为双峰型，北京沈阳银川为单峰型，对于日照时间较长的北京、银川和沈阳，臭氧对气温变化更敏感，且与风速呈弱的正相关，对于气温、湿度较高的广州、南京和成都，臭氧与日照和湿度相关性更好，且与风速呈弱的负相关。光化辐射通量春夏季大于秋冬季，日变化均为“单峰”型，受地理经度影响，北京南京沈阳最大值出现在12时，银川成都出现在13时。对光化辐射通量衰减作用由大到小依次为云光学厚度>气溶胶光学厚度>臭氧柱浓度>NO2柱浓度，光化辐射通量随气溶胶光学厚度增加而减小的变率要比随云光学厚度增加而减小的变率要小，光化辐射通量衰减率对较低的云光学厚度、单次散射反照率比大于0.6的强散射性气溶胶的变化更敏感，波长指数对光化辐射通量影响较小。辐射对J[O1D]、J[NO2]影响最大，其次是气温，传输作用对J[O1D]、J[NO2]和臭氧也有重要影响；J[O1D]和J[NO2]与AOD相关性最强，其次是PM10，再次是PM2.5，臭氧与AOD相关性最强，其次是SSA，再次是PM10，J[O1D]、J[NO2]和臭氧与AE相关性均最弱。项目明确了有利于形成银川臭氧污染的气象条件、环流形势、传输路径，有助于提升臭氧污染天气预报预警能力，同时，项目深入分析了TUV模拟性能及气溶胶、云等对光化辐射通量的影响，有助于理清气溶胶、云光学特性对光化辐射通量及臭氧的作用。