基于卫星遥感的海南地区对流层NO2长期变化及成因分析

利用OMI卫星反演的较高分辨率(0.125°×0.125°)对流层NO_2(Tro NO_2)柱浓度数据,分析了近12年海南岛TroNO_2柱浓度的时空变化,同时,结合MODIS卫星反演的气溶胶光学厚度(AOD)资料、海口市空气质量指数(AQI)、GDP、SO_2排放总量,以及民用汽车保有量等探究其长期变化与成因.结果表明:海南地区TroNO_2柱浓度空间分布表现为北半部高于南半部、四周沿海高于中部山区的特征,其中,北部地区最大值可达20×1014molec·cm~(-2)以上.近12年来海南地区TroNO_2柱浓度表现为上升的变化趋势.季节变化表现为冬季高于夏季,夏季浓度偏低和雨水的冲刷作用有关,而冬季偏高与旅游过冬人口增多和外源输送作用有密切联系.四季TroNO_2柱浓度均有不同程度的上升,而且季节差异在2010年以后有增大的趋势.海南地区TroNO_2柱浓度分布与岛上经济水平和人口分布关系密切,海南地区民用机动车拥有量近10年呈现快速的增加趋势,机动车尾气NO_2排放也不容忽视.

Satellite-based long-term trends analysis in TroNO2 over Hainan Island and its possible reason

This study analyzes temporal-spatial characteristics of the tropospheric column NO₂(TroNO₂, resolution:0.125°×0.125°) over Hainan Island using OMI satellite data, and further investigates the possible reasons by using information on aerosol optical depth(AOD), AQI in Haikou city, GDP, total SO₂ emissions, and the amount of private cars. It is found that TroNO₂ is larger in the north of Hainan Island, and is lower in the central mountainous area than the surrounding coastal regions. The maximum value in the north is 20×10¹⁴ molec·cm^-2. TroNO₂ over Hainan Island shows an increase trend for the past 12 years, with higher value in winter than summer. The lower TroNO₂ in summer is related to more precipitation, while the larger TroNO₂ in winter is attributed to increased tourism and outside transport. Since 2010, TroNO₂ has been increasing for all seasons in association with an increase of the seasonal differences. Spatial distribution of TroNO₂ exhibits a close relationship with the population distribution over Hainan Island. In addition, with rapid increase in private car during the past 10 year, NO₂ emissions of vehicle exhaust cannot be ignored.