Space-Based Constraints on Hydrocarbon Emissions in East Asia

Formaldehyde (HCHO) columns measured from space by solar backscatter allow quantitative mapping of reactive hydrocarbon emissions. We analyze measurements from the GOME satellite instrument between 1996 and 2001 over East Asia and compare the resulting monthly constraints on hydrocarbon emissions with the latest biogenic, anthropogenic, and biomass burning emission inventories. Multivariate regression, exploiting the spatial and seasonal variations of the HCHO column data, is used to quantify regional contributions from these different emission types. We show that current inventories are too low for anthropogenic emissions in winter and for biogenic and biomass burning emissions in summer. Large HCHO signals are consistently observed in early summer over the North China Plain, implying a large, previously unrecognized source from winter wheat harvesting and crop residual burning.