Development of a Prototype Operational Urban Greenhouse Gas Emissions Estimation System for the Washington, DC and Baltimore, MD Metropolitan Area

Climate change is a highly significant issue that must be addressed. Reducing emissions of greenhouse gases is a fundamental goal. Increased accurate and up-to-date greenhouse gas emissions data will improve stakeholder capabilities to set priorities for reduction efforts and assess their progress. A U.S. interagency effort is underway to develop a prototype operational greenhouse gas emissions estimation system. This presentation discusses an initial effort to estimate urban carbon dioxide (CO₂) and methane (CH₄) emissions. Initial urban scale emissions estimates will be performed for the Washington, DC and Baltimore, MD metropolitan area with plans to extend this effort to other urban areas with sufficient greenhouse gas measurements. Greenhouse gas observations from a dense network of tower based CO₂ and CH₄ observations from the National Institute of Standards and Technology (NIST) and Earth Networks, Inc. within and surrounding the Washington, DC and Baltimore, MD area and campaign-based mobile and aircraft measurements will be used within our measurement - modeling system. The modeling portion of our system includes operational National Weather Service (NWS) numerical weather prediction (NWP) models, the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model and the CarbonTracker-Lagrange inversion model. NWP meteorological fields are used to drive backward dispersion simulations with the HYSPLIT model initialized from greenhouse gas monitoring locations to identify locations of possible sources and sinks of CO₂ and CH₄ impacting observed concentrations at the measurement sites. HYSPLIT model output is fed into the CarbonTracker-Lagrange inversion model to obtain top-down estimates of greenhouse gas emissions. Improved emissions estimates will be useful to evaluate and improve emissions inventories, assess whether greenhouse gas emissions reduction targets are on track, and identify sources and their estimated magnitudes for emissions reductions strategies.