Fossil fuel CO₂ emissions mapping and measurements

• This joint NASA-DOE project (Vulcan) is developing maps of fossil fuel CO₂ emissions at high spatiotemporal resolution for the continental United States.  The work is led by Purdue University (Kevin R. Gurney <kgurney@purdue.edu>) in collaboration with the Lawrence Berkeley National Laboratory (Marc L. Fischer <mlfischer@lbl.gov>).  Vulcan is being built using a combination of measured data and inventory models developed by US-EPA for criteria pollutant emissions and then scaled to finer spatial scales using geographic information systems (GIS) data relevant for specific human activities. Carbon monoxide is obtained directly from EPA emission estimates in the National Emissions Inventory (EPA-NEI) for 2002.  CO₂ must be estimated separately because it is not currently comprehensively included of the NEI.  For large point sources, hourly continuous CO₂ emissions monitoring data are ingested in Vulcan directly.  For mobile sources, EPA NMIM and Mobil6.2 models are used to estimate hourly CO₂ emissions at the county level.  Mobile emissions are then disaggregated onto a national GIS data base of roadways.  For area sources including residential and small industries, EPA estimates of fuel use at 30km spatial and hourly temporal scales is disaggregated using census data on population and industrial activity.  First results from Vulcan (v0.1) are being compared with 1) DOE Energy Information Agency CO₂ emissions estimates (annual and monthly county level data by fuel type) and 2) independent data for major emissions sectors in California being gathered by Berkeley Lab in cooperation with the California Energy Commission and Air Resources Board. The public release of Vulcan 2002 fossil CO₂ emissions for the continental US is expected in winter 2007.

• A collaborative project between UC Irvine (Jim Randerson <jranders@uci.edu>) and Lawrence Berkeley National Laboratory (William Riley <wjriley@lbl.gov>), compared measured and predicted ¹⁴C content of annual grasses in California.  Grass samples were collected at the end of the growing season across California and compared with growing-seasonal-averaged ¹⁴C uptake predicted with a coupled landsurface-atmosphere model (MM5-ISOLSM) with fossil CO₂ emissions estimated in a constant scaling from EPA NOx emissions.  Model predictions compared well with the measurements, indicating that growing season averaged atmospheric fossil CO₂ covers a large range from approximately 14 ppm in the Los Angeles area to less than 1 ppm on the North Coast of California.  In a result that has important implications for the North American Carbon Program, more than 50% of the fossil CO₂ emitted from California is blown to the south into Mexico rather than east into the continental United States.
  

Publications

Riley, W.J, D.Y. Hsueh, J.T. Randerson, M.L. Fischer, J.G. Hatch, D.E. Pataki, and M.L. Goulden (2007). Where do Fossil Fuel Carbon Dioxide Emissions from California Go? An Analysis Based on Radiocarbon Observations and an Atmospheric Transport Model. JGR-Biogeosciences (submitted).