土地利用变化与大气污染物对太原市热环境的影响研究

Effects of Land Use Change and Air Pollutants on Thermal Environment in Taiyuan City

COVID-19疫情封控是研究人类活动减少对城市热环境影响的重要“窗口期”。选取太原市白天MOD11A2温度数据(LST)、大气环境监测数据(PM_(2.5)、PM_(10)、SO_(2)、NO_(2)、CO和O_(3))以及土地利用数据,探讨COVID-19疫情封控前后(2015—2021年)LST时空变化以及影响因素。结果表明,2015—2021年,太原市建设用地、林地和水体的面积呈增加的趋势,而草地面积却明显减小。不同土地利用类型白天LST均表现出一定的规律,即建设用地>耕地>水体>草地>林地。建设用地和耕地对城市热岛的贡献度最高,林地和草地降温效果显著。2017年以来大气污染物的降低与该市的环保政策有关。2020以后的COVID-19封控政策促进了空气质量进一步转好。大气污染物与热环境是相互作用的,2017—2019年太原市LST缓慢增加可能与PM_(2.5)降低导致短波辐射增加有关,2021年O_(3)增加可能是由LST的升高引起的。COVID-19疫情防控前后,太阳辐射对林地和草地LST影响相对显著。2021年不同土地类型的LST升高可能与大气污染颗粒明显减少有关。

COVID-19 epidemic urban lockdown is an important“window period”for studying the impact of reduced human activities on the urban thermal environment.The study selected the daytime MOD11A2 land surface temperature(LST)data,atmospheric environmental monitoring data(PM_(2.5),PM_(10),SO_(2),NO_(2),CO and O_(3))and land use data of Taiyuan City to explore the spatiotemporal changes and influencing factors of LST before and after the urban lockdown(from 2015 to 2021).The results showed that from 2015 to 2021,the area of construction land,forest land and water body in Taiyuan City increased,while the area of grassland decreased significantly.The LST of different land use types showed certain rules,namely construction land>cultivated land>water body>grassland>forest land.The contribution of construction land and cultivated land to urban heat island was the highest,and the cooling effect of forest land and grassland was significant.The reduction of air pollutants since 2017 was related to the city′s environmental protection policies.The COVID-19 lockdown policy after 2020 promoted the further improvement of air quality.Air pollutants interacted with thermal environment.The slow increase of LST from 2017 to 2019 might be related to the increase of short-wave radiation caused by the decrease of PM_(2.5),and the increase of O_(3)in 2021 might be caused by the increase of LST.The effect of solar radiation on LST of forest land and grassland was relatively significant before and after COVID-19 lockdown.The increase of LST of different land use types in 2021 might be related to the significant reduction of atmospheric pollution particles.