基于中分辨率遥感数据的秸秆露天焚烧碳排放估算——以呼和浩特市为例

Estimation of Carbon Emissions from Straw Burned Openly Based on Medium Resolution Remote Sensing Data:A Case Study of Hohhot

秸秆露天焚烧是农业生产的主要碳排放活动。为全面掌握秸秆露天焚烧的时空分布,准确获取秸秆露天焚烧的碳排放量,以2014-2020年Satellite See Fire数据为数据源,提取呼和浩特市的秸秆火点,分析其数量的年际、月际和区域变化规律;基于2020年Sentinel-2遥感影像,使用归一化燃烧指数(NBR)、燃烧面积指数(BAI)以及改进的燃烧指数(NBRSWIR11、BAI_(Red Edge5)、BAI_(Red Edge6)、BAI_(Red Edge7))提取研究区主要月份的火烧迹地,通过筛选燃烧指数、确定估算阈值,进而得到秸秆露天焚烧的碳排放量。结果表明:2014-2020年呼和浩特市秸秆火点主要集中在土默特左旗、托克托县、和林格尔县以及市区南部,火点数量整体呈下降趋势;春季(3、4月)和秋季(10、11月)为秸秆露天焚烧的主要月份,其中3、10、11月提取火烧迹地的最佳燃烧指数和阈值分别为BAI和78、120与110,4月提取火烧迹地的最佳燃烧指数和阈值分别为BAIRed Edg e5和78;2020年秸秆露天焚烧面积为16万hm^(2),秸秆露天焚烧总量为114.8万t,CH4、CO、CO_(2)和碳排放总量分别为0.25万t、11.73万t、159.62万t和48.75万t。

Open-field straw burning is a major contributor to carbon emissions within agricultural practices.This study employs data from Satellite See Fire(2014-2020)to investigate the spatiotemporal dynamics of straw open burning in Hohhot,thereby accurately quantifying its interannual,monthly,and regional variation of carbon emissions.By exploiting the 2020 Sentinel-2 remote sensing imagery,indices such as the Normalized Burning Index(NBR),Burning Area Index(BAI),and an enhanced set of burning indices(NBRSWIR11、BAI_(Red Edge5)、BAI_(Red Edge6)、BAI_(Red Edge7))were used to determine the principal months'burned areas.Subsequent to index selection and threshold estimation,carbon emissions from straw open burning were ascertained.The results showed a spatial concentration of straw fires from 2014-2020 in Tumd Left Banner,Togtoh County,Horinger County,and southern Hohhot,with a declining trend in fire incidences.Major open burning seasons were identified as spring(March-April)and autumn(October-November).The optimal indices and thresholds for burn extraction during these periods were found to be BAI(with thresholds of 78,120,and 110)and BAIRed Edges with a threshold of 78,respectively.In 2020,open burning affected an area of 160000 hm²and consumed approximately 1.148 million tons of straw.This resulted in total emissions of 2500 tons of CH4,117300 tons of CO,1.5962 million tons of CO_(2),and 487500 tons of carbon.