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Applying OMI and TROPOMI NO2 observations in EPA’s CMAQ modeling framework (HAQAST meeting)
Citation:
East, J., B. Henderson, S. Napelenok, S. Koplitz, R. Pierce, A. Lenzen, D. Tong, R. Gilliam, G. Sarwar, AND F. Garcia-Menendez. Applying OMI and TROPOMI NO2 observations in EPA’s CMAQ modeling framework (HAQAST meeting). HAQAST, Virtual, Virtual, January 20 - 21, 2022.
Impact/Purpose:
This research presents results of implementing NO2 data assimilation into the CMAQ model and shares information about how research at EPA uses satellite data.
Description:
The sub-product is a presentation at the HAQAST Update22 meeting. Long-range transport of ozone (O3) to the US has human health and regulatory impacts, and is produced, in part, from international nitrogen oxides (NOx) emissions. Accurately representing international O3 transport in hemispheric and global-scale air quality models requires accurate emissions inventories. However, developments of global bottom-up emissions inventories can be out-of-date and uncertain, particularly in developing countries, limiting the representation of international emissions and transport in air quality models. This research introduces a satellite data assimilation system for inverse modeling of northern hemispheric NOx emissions which offers opportunities to improve representations of long-range O3 transport and model performance. The system is capable of assimilating observations from OMI and TROPOMI satellite instruments, and we compare the capabilities of OMI and TropOMI NO2 observations in NOx emissions estimations. The system can provide estimates of NOx emissions in China, India, Europe, US, and the Mexico based on a finite-difference mass balance inversion. We assimilate data from OMI and TropOMI separately in EPA’s Community Multiscale Air Quality (CMAQ) model for 2019 over the northern hemisphere and perform NOx emissions inversions for each assimilation. We compare NOx emissions estimated with observations from each satellite instrument and analyze model performance: (1) without any satellite derived information, (2) with assimilated NO2, and (3) with satellite derived emissions updates, for each satellite. Results suggest that OMI inferred adjustments tend to increase northern hemisphere NOx emissions from the base case emissions by 9% while TROPOMI inferred adjustments tend to decrease base case emissions by 33%. Adjustments from both satellites can lead to modest impacts on transpacific O3 in the free troposphere of up to 5 ppb.
