Estimating CH4 and CO Emissions in California's Urban and Rural Regions Using Multi-site Observations
Abstract
California's commitment (Assembly Bill 32) to reduce total greenhouse gas (GHG) emissions to 1990 levels by 2020 (~20% reduction) requires quantification of current GHG emissions. We will present atmospheric inversion estimates of California's total CH4 emissions for summer 2013, using data from multiple sites covering urban and rural areas of California's South Coast Air Basin (SoCAB), Central Valley, and San Francisco Bay Area. We will also use measured CO from two tall-tower sites (Central Valley and SoCAB) to quantify CO emissions as well as to evaluate atmospheric transport. We use Bayesian inverse modeling to estimate the CH4 and CO emissions from discrete regions of California by combining the atmospheric measurements, upstream background, high-resolution prior emission maps, and predicted atmospheric transport from WRF-STILT. We quantify site-specific model-measurement uncertainties due to transport using meteorological data from a network of atmospheric profilers and in-situ sensors, due to background using oceanic and aircraft observations, and the prior emissions. To reduce the uncertainty in transport, we assimilate available meteorological measurements from surface and upper air stations, and wind profilers into the WRF model. Preliminary inversion results during September 2010 - June 2011 and summer of 2012 suggest that state total CH4 emissions are 1.2 - 1.8 times higher than the current CARB inventory and we will update these estimates. We expect the results of this study will significantly improve upon existing work in quantifying CH4 and CO emissions in California's urban and rural regions.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFM.A44F..07J
- Keywords:
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- 0365 ATMOSPHERIC COMPOSITION AND STRUCTURE Troposphere: composition and chemistry;
- 0368 ATMOSPHERIC COMPOSITION AND STRUCTURE Troposphere: constituent transport and chemistry;
- 3355 ATMOSPHERIC PROCESSES Regional modeling;
- 0490 BIOGEOSCIENCES Trace gases