Grantee Research Project Results

Regional adjustment of emission strengths via four dimensional data assimilation.

Citation:

Park S-K, Russell AG. Regional adjustment of emission strengths via four dimensional data assimilation. Asia-Pacific Journal of Atmospheric Sciences 2013;49(3):361-374.

Abstract:

The Four-Dimensional Data Assimilation was performed to evaluate source emission strengths over the United States. The USEPA Models-3 system (CMAQ/MM5/SMOKE) and ridge regression are used as the forward and inverse models, respectively. The continental US is divided into six regions, and data assimilation is performed for each region in July 2001 and January 2002. In addition, two separate scaling factors are calculated for weekdays and weekends. Results show that base emissions for CO and SO2 sources are relatively accurate. Base emissions for PEC source are overestimated 100%, but those for POA source are underestimated up to 70% when compared with the adjusted emissions. Emissions for NH3, NOx, and PMFINE sources are relatively accurate in July 2001, but those in January 2002 are around 100% higher than the adjusted emissions. Base VOC emissions in July 2001 are similar to the adjusted emissions but those in January 2002 are underestimated up to 70% when compared with the adjusted emissions. Though the emission adjustment itself improves the overall air quality model performance, a better improvement is expected with the modification of speciation profiles and temporal allocations in the Models-3 system, as well.