Understanding emission fluxes from earth's surface has considerable scientific importance because the variability of atmospheric composition is largely driven by emissions. Due to the rapid regional economic growth, emissions in East Asia have degraded regional air quality and visibility and damaged human health. East Asia emissions also contribute a large share of the global emissions and dominate the Asian continental outflow that travels across the Pacific. Hence they also have significant impacts on global air quality and climate and attract great attention of scientists and policy makers.

To date developing an understanding of emissions has largely relied on bottom-up approaches that aggregate fuel combustion data and emission factors. The large uncertainty in East Asia bottom-up inventories hampers interpretation of observation data and has been recognized as the bottleneck in limiting the predictive performances of chemical transport models. The community has made considerable efforts to reduce uncertainties in emission inventories, e.g., development of improved emission models, application of inverse models with top-down constraints from in situ and satellite observations. However, those different approaches are rarely compared and validated with each other. There are still large gaps among different top-down/bottom-up inventories.

Organized by the Global Emissions InitiAtive (GEIA) China Working Group, the East Asia Emissions Assessment (EA2) is designed to bridge these gaps through the integration of different approaches. The assessment includes inter-comparison of current bottom-up inventories in East Asia, development of novel emission inventory models, observation-based constraints on emissions, and evaluation and uncertainty analysis of different emission quantification approaches. The outputs from EA2 studies will not only help reduce uncertainties in East Asia inventories but also provide improved emission quantification methodologies that can be applied to other world regions.