多源卫星遥感估算中国东部秋季秸秆焚烧污染排放的研究

In recent years, the severely and frequently polluted events over the North China and Northeast China during autumn were related with agricultural residue burning, which emitted amounts of polluted gases and particles. These pollutants superimposed the emissions from urban and industry, which had elevated the level of pollutions. Most of agricultural burning inventories were based on statistic data or fire products from polar satellites, which had low resolutions and large uncertainties and can’t reflect the types of small and intermittent wildfires of residue burning the in China. Thus, the emissions from open agricultural burning are underestimated. This project will confirm the emission factors of maize straw, the main crop in eastern China during autumn, through field experiments based on the real burning modes using by farmers. The high resolution of fire counts and fire radiation power (FRP) were retrieved using multi-sense remote sensing, and these fires were further identified based on high-precision land cover data and filed investigation. Consequently, using FRP data, division of crop planting area in China and residue types, the emission characters of open agricultural burning in eastern China during autumn will be explored, and a high resolution emission inventory (hourly and daily scales) will be established. This research will promote the precise of emission inventory, which is very crucial for accurate simulation by air quality models and urgent for haze pollution prevention and control.

近年来我国华北、东北秋季频发的重霾污染事件与农业秸秆焚烧密切相关，焚烧释放的大量污染气体和颗粒物，叠加城市、工业区的污染排放，加剧霾污染强度。现有秸秆焚烧排放清单基于省级统计年鉴或者单一极轨卫星火点产品，时空分辨率低、不确定性大，无法反映我国秸秆焚烧时间随意、燃烧迅速的特点，排放量被大大低估。本研究拟基于调研的田间焚烧方式，利用野外火烧实验准确测定秋季主要作物玉米的排放因子；利用新一代极轨和静止卫星联合反演高时空分辨率的火点及辐射功率，并基于高精度土地覆盖数据，以及野外燃烧的定位和调查，判识卫星火点；最终利用能识别秸秆焚烧小火的卫星火点辐射功率数据，结合我国农作物种植区划分和秸秆类型，揭示秋季我国东部秸秆焚烧排放特征，建立高时空分辨率的排放清单（时和日尺度）。研究成果将有助于提高区域秸秆焚烧排放清单的精确度，为空气质量模式精确模拟提供必要初始数据，是当前区域霾污染防治的迫切需求。

近年来我国东部秋季频发的重霾污染事件与农业秸秆焚烧密切相关，叠加其他人为污染排放，加剧霾污染强度。现有秸秆焚烧排放清单更新滞后，且基于卫星的清单低估显著。本项目基于2014年相继发布的高时空分辨率的Suomi-NPP极轨卫星和日本Himawari-8静止卫星，识别和确定我国东部农田火点及火辐射功率(FRP)，并在东北和华北外场实验获得的主要农作物(水稻和玉米)秸秆燃烧排放特征和排放因子，最终结合农作物种植区划分，利用双星的FRP数据和本地化排放因子，建立较为准确的高时空分辨率的秸秆燃烧排放清单。主要成果为：1.建立中国本地化卫星农业火点判识算法和自动化提取程序，将NPP和Him-8卫星农田火点识别准确度分别提高到93.4%和95%以上；2.利用野外露天燃烧实验获取东北本地化水稻和玉米秸秆污染物排放特征和排放因子；3.基于双星联合，利用FRP数据和本地化排放因，估算了逐日0.1度分辨率的华北地区(2012-2015年)和东北地区(2014-2019年)污染物排放清单。结果显示华北地区秸秆禁烧效果显著，污染物排放量逐渐下降，东北地区受秸秆禁烧政策影响，使燃烧峰值从秋季（9-10月）转移到次年春季（2-4月），并且本项目计算的秸秆干物质量高出全球主流排放清单（GFAS、GFED和FINN）2-5倍。本研究结果不仅为区域空气质量模型提供必要的基础数据，有助于精确评估秸秆露天燃烧造成的环境效应和气候效应，提高大气污染成因诊断以及预报的准确性和时效性，也为助力“碳达峰、碳中和”提供秸秆露天燃烧碳排放数据。