@article{27962,
  keywords = {Emissions, Carbon dioxide, Simulation, Biosphere, Fossil Fuel, Inversion},
  author = {Marc L Fischer and Nicholas Parazoo and Kieran Brophy and Xinguang Cui and Seongeun Jeong and Junjie Liu and Ralph Keeling and Thomas E Taylor and Kevin R Gurney and Tomohiro Oda and Heather Graven},
  title = {Simulating Estimation of California Fossil Fuel and Biosphere Carbon Dioxide Exchanges Combining In-situ Tower and Satellite Column Observations},
  abstract = {<p>We report simulation experiments estimating the uncertainties in California regional fossil fuel 36 and biosphere CO<sub>2</sub> exchanges that might be obtained using an atmospheric inverse modeling 37 system driven by the combination of ground-based observations of radiocarbon and total CO<sub>2</sub>, 38 together with column-mean CO<sub>2</sub> observations from NASA’s Orbiting Carbon Observatory 39 (OCO-2). The work includes an initial examination of statistical uncertainties in prior models for 40 CO<sub>2</sub> exchange, in radiocarbon-based fossil fuel CO<sub>2</sub> measurements, in OCO-2 measurements, 41 and in a regional atmospheric transport modeling system. Using these nominal assumptions for 42 measurement and model uncertainties, we find that flask measurements of radiocarbon and total 43 CO<sub>2</sub> at 10 towers can be used to distinguish between different fossil fuel emissions data products 44 for major urban regions of California. We then show that the combination of flask and OCO-2 45 observations yield posterior uncertainties in monthly-mean fossil fuel emissions of ~ 5-10%, 46 levels likely useful for policy relevant evaluation of bottom-up fossil fuel emission estimates. 47 Similarly, we find that inversions yield uncertainties in monthly biosphere CO<sub>2</sub> exchange of ~ 48 6%-12%, depending on season, providing useful information on net carbon uptake in 49 California’s forests and agricultural lands. Finally, initial sensitivity analysis suggests that 50 obtaining the above results requires control of systematic biases below approximately 0.5 ppm, 51 placing requirements on accuracy of the atmospheric measurements, background subtraction, and 52 atmospheric transport modeling.</p>},
  year = {2017},
  journal = {Journal of Geophysical Research: Atmospheres},
  volume = {122},
  pages = {3653-3671},
  month = {03/2017},
  doi = {10.1002/2016JD025617},
}