卫星观测协同估算西北煤炭基地污染气体及CO2排放量

Satellite-based collaborative estimation of pollutant gases and CO2 emissions in coal-based regions of Northwestern China

  • 摘要: 煤炭生产重心自2010年后持续向资源禀赋优良、开采条件优越的西部区域转移。西北地区的煤、电、化三大主导产业逐渐兴起,在其生产运营过程中产生了大量的空气污染物与CO2。然而,现有的地面监测站点数量较为有限,难以全面且精准地反映基地建设所引发的排放状况。相比之下,卫星遥感技术具备覆盖面广和成本相对较低的优势。采用基于大气质量守恒方法与哨兵−5P卫星搭载的对流层观测仪(TROPOMI)数据,“自上而下”地估算2019—2020年西北煤炭基地污染气体(NOx、CO及SO2)的排放量。由于污染气体和温室气体呈现“同源、同步和同区”的特征,根据“自下而上”多尺度排放清单模型(MEIC)的排放量关系,间接估算了CO2排放量。结果表明:基于大气质量守恒原则拟合获得的物理化学驱动因子合理反映了西北地区的煤炭消费水平、地形因素和排放特征,展现了年度分布的良好一致性。MEIC清单对西北地区燃煤源污染气体的排放存在低估,主要原因包括:清单中西北地区存在许多接近零值的区域,但忽视了居民散烧煤或野外煤火;统计数据缺乏,导致许多新兴中小型燃煤工业和其他排放源未被充分记录。使用单一物种间接估算CO2排放量的误差较大,因此综合NOx、CO和SO2的结果更为准确。估算结果与MEIC展现了时空分布的一致性,但87%的网格排放量高于MEIC,凸显了在低排放量和高排放量方面提高CO2排放清单精度的必要性。

     

    Abstract: Since 2010, coal production in China has increasingly shifted to the western regions, characterized by superior resource endowments and favorable mining conditions. The three major industries—coal, electricity, and chemicals—in the northwestern region have experienced significant growth, leading to substantial emissions of air pollutants and CO2 during both production and operations. However, the limited number of existing ground monitoring stations hinders a comprehensive and precise reflection of the emissions induced by these industrial bases. In contrast, satellite remote sensing offers broader coverage at relatively lower costs. An atmospheric mass-conserving approach and the Tropospheric Monitoring Instrument (TROPOMI) onboard Sentinel-5 Precursor datasets are employed to quantify the emissions of NOx, CO, and SO2 from the northwestern coal-based regions from 2019 to 2020. Given the “co-synchronous, co-located, and co-sourced” characteristics of pollutants and greenhouse gases, CO2 emissions are indirectly estimated based on established bottom-up emission relationships. The results show that: The physical and chemical driving factors derived from the mass-conserving equation appropriately reflect coal consumption levels, topographic factors, and emission characteristics in the northwestern regions, exhibiting consistency in annual distribution. An underestimation of coal-fired source pollutant emissions is also revealed in the northwestern regions according to existing inventories. Contributing factors include numerous near-zero value areas in the inventory despite prevalent residential coal burning and coal fires. Additionally, a lack of statistical data results in many emerging small and medium-sized coal-fired industries and other emission sources being inadequately recorded. The use of a single species for indirectly estimating CO2 emissions leads to significant errors; Hence, integrating results from NOx, CO, and SO2 provides more precise estimates. The temporal and spatial distribution consistency is demonstrated with the Multi-resolution Emission Inventory model for Climate and air pollution research (MEIC). However, in 87% of valid grids, the CO2 emission estimates exceed those reported by MEIC, underscoring the necessity of improving the accuracy of CO2 emission inventory for both low and high emission scenarios.

     

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