Abstract We use 2005–2016 observations of formaldehyde (HCHO) columns over China from the OMI, GOME-2, and SCIAMACHY satellite instruments to evaluate long-term trends in emission inventories of volatile organic compounds (VOCs) that affect air quality. The observations show large increases over 2005–2016 in the North China Plain (+1.1 ± 0.5% a−1 relative to 2005) and the Yangtze River Delta region (+1.5 ± 0.4% a−1 relative to 2005), consistent with the trend of anthropogenic VOC emissions in the Multi-resolution Emission Inventory for China (MEIC). Unlike other pollutants, VOC emissions have not been decreasing in recent years. An exception is the Huai River Basin in rural eastern China where the satellite data show rapidly decreasing VOC emissions since the early 2010s that appear to reflect bans on agricultural fires.
Abstract Gas flaring is a commonly used practice in the oil and gas sector that leads to key air pollutant and greenhouse gas emissions. Here we use multipollutant (NO2, SO2) satellite observations from 2005 to 2017 to quantify gas flaring activity in Mexico's offshore production cluster, which produces 50–70% of the country's oil and is among the world's largest oil fields. We estimate annual flared gas volume ranging from 5.5 to 20 × 109 m3 over the Mexican offshore corresponding to >40% associated gas production, which is significantly larger than for instance offshore United States where reportedly <3% of associated gas is flared. The 13-year record of satellite-derived gas flaring indicates a drastic increase until 2008 and a decline afterward. While the increased flaring is associated with efforts to enhance oil production, the post-2008 decline is linked to an expanding capacity of associated gas utilization, providing a continuing opportunity to reduce flaring for environmental and economic benefits.
Satellite observations of formaldehyde (HCHO) columns provide top-down constraints on emissions of highly reactive volatile organic compounds (HRVOCs). This approach has been used previously in the US to estimate isoprene emissions from vegetation, but application to anthropogenic emissions has been stymied by lack of a discernable HCHO signal. Here we show that temporal oversampling of HCHO data from the Ozone Monitoring Instrument (OMI) for 2005–2008 enables detection of urban and industrial plumes in eastern Texas including Houston, Port Arthur, and Dallas/Fort Worth. By spatially integrating the HCHO enhancement in the Houston plume observed by OMI we estimate an anthropogenic HCHO source of 250 ± 140 kmol h −1 . This implies that anthropogenic HRVOC emissions in Houston are 4.8 ± 2.7 times higher than reported by the US Environmental Protection Agency inventory, and is consistent with field studies identifying large ethene and propene emissions from petrochemical industrial sources.