Diurnal and Intra-Annual Variations in Greenhouse Gases at Fixed Sites in the San Francisco Bay Area
Abstract
The Bay Area Air Quality Management District, the San Francisco Bay Area's air quality regulatory agency, has set a goal to reduce the region's greenhouse gas (GHG) emissions to 80% below 1990 levels by 2050, consistent with the State of California's climate goals. Recently, the Air District's governing board adopted a 2017 Clean Air Plan which lays out the agency's vision and includes actions to put the region on a path towards achieving the 2050 goal while also reducing air pollution and related health impacts. The Plan includes GHG rule-making efforts, policy initiatives, local government partnerships, outreach, grants, and incentives, encompassing over 250 specific implementation actions across all economic sectors to effect ambitious emission reductions in the region. To track trends in atmospheric observations of GHGs and associated species and monitor changes in regional emission patterns, the Air District has established a fixed site network (CO2, CH4, CO) of one generally upwind site (Bodega Bay - on the coast north of Marin County) and three receptor sites (Bethel Island - east of the major refineries, in the Sacramento River Delta; Livermore - east of the bulk of the East Bay cities; and San Martin - south of the major city of San Jose). Having collected over a year of data for each of the fixed sites, the Air District is now investigating spatial and temporal variations in GHG emissions. Concentrating on variations in diurnal cycles, we see the commonly observed pattern of seasonal changes in diurnal amplitude at all sites, with larger variations during the winter than the summer, consistent with seasonally varying daily changes in planetary boundary layer heights. Investigations explore the weekday/weekend effect on the diurnal patterns and the effect of seasonal wind direction changes on the intra-annual variations of the local enhancements. The Air District is beginning to investigate the ways in which the fixed site network reflects the dominant upwind GHG emissions.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.A23G2457N
- Keywords:
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- 0345 Pollution: urban and regional;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0493 Urban systems;
- BIOGEOSCIENCES;
- 1610 Atmosphere;
- GLOBAL CHANGE