Publication Date:
2019-09-21
Description:
We estimate the overall CO2, CH4, and CO flux from the South Coast Air Basin using an inversion that couples Total Carbon Column Observing Network (TCCON) and Orbiting Carbon Observatory-2 (OCO-2) observations, with the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model and the Open-source Data Inventory for Anthropogenic CO2 (ODIAC). Using TCCON data we estimate the direct net CO2 flux from the So-CAB to be 10426 Tg CO2 yr(exp -1) for the study period of July 2013August 2016. We obtain a slightly higher estimate of 12030 Tg CO2 yr(exp -1) using OCO-2 data. These CO2 emission estimates are on the low end of previous work. Our net CH4 (36090 Gg CH4 y(exp -1)) flux estimate is in agreement with central values from previous top-down studies going back to 2010 (342440 Gg CH4 yr(exp -1)). CO emissions are estimated at 487122 Gg CO yr(exp -1), much lower than previous top-down estimates (1440 Gg CO yr(exp -1)). Given the decreasing emissions of CO, this finding is not unexpected. We perform sensitivity tests to estimate how much errors in the prior, errors in the covariance, different inversion schemes, or a coarser dynamical model influence the emission estimates. Overall, the uncertainty is estimated to be 25%, with the largest contribution from the dynamical model. Lessons learned here may help in future inversions of satellite data over urban areas.
Keywords:
Earth Resources and Remote Sensing
Type:
GSFC-E-DAA-TN73293
,
Atmospheric Chemistry and Physics (ISSN 1680-7316) (e-ISSN 1680-7324); 18; 22; 16,271-16,291
Format:
application/pdf
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