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.
Open fires play a significant role in atmospheric pollution and climatic change. This work aims to develop an emission inventory for nonagricultural open fires in Asia using the newly released MODIS (Moderate Resolution Imaging Spectroradiometer) burned area product (MCD45A1), as the MODIS sensor cannot efficiently detect field crop residue burning. Country-level or province-specific biomass density data were used as fuel loads. Moisture contents were taken into account when calculating combustion factors for grass fuel. During the nine fire years 2000–2008, both burned areas and fire emissions clearly presented spatial and seasonal variations. Extensive nonagricultural open fires were concentrated in the months of February and March, while another peak was between August and October. Indonesia was the most important contributor to fire emission, which was largely attributable to peat burning. Myanmar, India, and Cambodia together contributed approximately half of the total burned area and emission. The annual emissions for CO 2 , CO, CH 4 , NMHC s , NO x , NH 3 , SO 2 , BC, OC, PM 2.5 , and PM 10 were 83 (69–103), 6.1 (4.6–8.2), 0.38 (0.24–0.57), 0.64 (0.36–1.0), 0.085 (0.074–0.10), 0.31 (0.17–0.48), 0.030 (0.024–0.037), 0.023 (0.020–0.028), 0.27 (0.22–0.33), 2.0 (1.6–2.6), and 2.2 (1.7–2.9) Tg yr − 1 , respectively. This inventory has a daily temporal resolution and 500 m spatial resolution, and covers a long period, from April 2000 to February 2009. It could be used in global and regional air quality modeling.