Analysis of the trends in ambient methane in the Baltimore-Washington region and comparison to model outputs.
Abstract
There has been an unprecedented rise in natural gas production and usage in the continental United States. The increase in natural gas activity can have implications for air quality and greenhouse gas footprint. Trends of methane, the primary component of natural gas, can be used to understand the sources of natural gas emissions. Methane measurements from the towers in the region display a distinct diurnal cycle with a maximum in the early morning and at nighttime. The presence of such a distinct diurnal cycle indicates significant local emissions. We have been studying how well models capture the methane observations and compared modeled methane enhancements from WRF-STILT, run with various inventories, to observed enhancements. The 5th percentile of the data is subtracted from both the observations and model enhancements. We observe that discrepancies between model and observations are higher during early morning and nighttime hours than in afternoon hours when the boundary layer is well-mixed. When running EDGAR 4.3.2 inventory, the model reproduces observed diurnal patterns better than other inventories (EPA, EDGAR 4.2, EDGAR 5). For all inventories, we find especially significant discrepancies between modeled and observed methane enhancements at the tower on Maryland's Eastern shore (BUC), in an area of extensive estuaries and other wetlands. The model does not account for wetland emissions, and the fact that emissions peak during summer at BUC, suggests natural, biogenic process as the dominant source of methane at this site. Future work would involve incorporating wetland emissions to understand the discrepancies between model and observation at BUC This research aims to understand better what sources of methane explain the observed trends in ambient methane and how we can quantify the emissions. Such studies will help quantify the emissions from each source and to reduce emissions from these sectors.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMB066.0028S
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0469 Nitrogen cycling;
- BIOGEOSCIENCES;
- 0490 Trace gases;
- BIOGEOSCIENCES