基于火点辐射能量的2017—2021年广西秸秆露天燃烧排放时空分析

基于2017—2021年MODIS、VIIRS和Himawari-8等多套卫星的火点辐射能量(FRE)和云量反演数据,使用更高分辨率的火点替代相邻位置低分辨率火点的融合方法,利用晴空的火点分布数据对被云遮蔽的区域进行补偿,核算得到了2 km高分辨率的广西秸秆露天燃烧排放数据,并针对2017—2021年的广西秸秆露天燃烧排放量展开精细的时空分布研究。结果表明:2017—2021年广西秸秆露天燃烧的CO、NO_x、SO₂、NH₃、VOCs、PM₁₀和PM_2.5的年排放量均值分别为12.91万、0.78万、0.16万、0.17万、2.77万、2.26万、2.21万t,排放高值区域分布在广西中部及西南部。秸秆露天燃烧排放的主要时间集中在冬、春季节(10月至次年3月),时值晚稻收割期和甘蔗榨季,占全年排放量的60%以上。广西秸秆露天燃烧PM_2.5年均排放量是全广西PM_2.5人为源年排放量的8.74%,通过逐日排放贡献分析发现,秸秆露天燃烧具有短期排放量较大的特点,2017—2021年,在1—2月有34 d出现秸秆露天燃烧导致PM_2.5排放量超过人为源排放量50%的情况。

Evaluation of Emissions from Open Crop Residue Burning in Guangxi (2017-2021) Based on Fire Radiative Energy Data

Based on fire radiative energy of fires detected by the MODIS,VIIRS and Himawari-8 from 2017 to 2021,with the methods of replacing fires of lower resolution with fires of higher resolution in adjacent locations and using cloud data from satellites and fire distribution data as supplementary information to areas covered by clouds,a 2km high-resolution open crop residue burning emissions in Guangxi was established.Spatial and temporal distribution of emissions from open crop residue burning in Guangxi for recent five years were studied.The results showed that the average annual emissions of CO,NO_x,SO₂,NH₃,VOCs,PM₁₀ and PM_2.5 from open crop residue burning in Guangxi from 2017 to 2021 were 129.1,7.8,1.6,1.7,27.7,22.6 and 22.1 thousand tons,respectively.The regions with high emission value were distributed in the central and southwest of Guangxi.Open crop residue burning emissions often occurred in winter and spring (October to March of the next year),corresponding to the late rice harvest period and sugarcane crushing season,accounting for more than 60% of the annual emission.The average annual emission of PM_2.5 from open crop residue burning was 8.74% of the annual anthropogenic emission in Guangxi.Open crop residue burning emitted large amount of pollutant on certain days.From 2017 to 2021,in January and February there were 34 days when emission of PM_2.5 from open crop residue burning exceeded 50% of anthropogenic emission in Guangxi.