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Title: Simulating estimation of California fossil fuel and biosphere carbon dioxide exchanges combining in situ tower and satellite column observations

Abstract

Here, we report simulation experiments estimating the uncertainties in California regional fossil fuel and biosphere CO 2 exchanges that might be obtained by using an atmospheric inverse modeling system driven by the combination of ground-based observations of radiocarbon and total CO 2, together with column-mean CO 2 observations from NASA's Orbiting Carbon Observatory (OCO-2). The work includes an initial examination of statistical uncertainties in prior models for CO 2 exchange, in radiocarbon-based fossil fuel CO 2 measurements, in OCO-2 measurements, and in a regional atmospheric transport modeling system. Using these nominal assumptions for measurement and model uncertainties, we find that flask measurements of radiocarbon and total CO 2 at 10 towers can be used to distinguish between different fossil fuel emission data products for major urban regions of California. We then show that the combination of flask and OCO-2 observations yields posterior uncertainties in monthly-mean fossil fuel emissions of ~5–10%, levels likely useful for policy relevant evaluation of bottom-up fossil fuel emission estimates. Similarly, we find that inversions yield uncertainties in monthly biosphere CO 2 exchange of ~6%–12%, depending on season, providing useful information on net carbon uptake in California's forests and agricultural lands. Finally, initial sensitivity analysis suggests thatmore » obtaining the above results requires control of systematic biases below approximately 0.5 ppm, placing requirements on accuracy of the atmospheric measurements, background subtraction, and atmospheric transport modeling.« less

Authors:
ORCiD logo [1]; ORCiD logo [2];  [3]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [4];  [5];  [6]; ORCiD logo [7]; ORCiD logo [8]; ORCiD logo [3]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. California Inst. of Technology (CalTech), Pasadena, CA (United States)
  3. Imperial College London, London (United Kingdom)
  4. Jet Propulsion Lab., Pasadena, CA (United States)
  5. Univ. of California, San Diego, La Jolla, CA (United States)
  6. Colorado State Univ., Fort Collins, CO (United States)
  7. Arizona State Univ., Tucson, AZ (United States)
  8. NASA Goddard Space Flight Center (GSFC), Greenbelt, MD (United States); Univ. Space Research Assoc., Columbia, MD (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
Energy Analysis & Environmental Impacts; USDOE
OSTI Identifier:
1364604
Alternate Identifier(s):
OSTI ID: 1402389
Report Number(s):
LBNL-1007266
Journal ID: ISSN 2169-897X; ir:1007266
Grant/Contract Number:
AC02-05CH11231
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Geophysical Research: Atmospheres
Additional Journal Information:
Journal Volume: 122; Journal Issue: 6; Journal ID: ISSN 2169-897X
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 54 ENVIRONMENTAL SCIENCES; fossil fuel; biosphere; emissions; carbon dioxide; simulation; inversion

Citation Formats

Fischer, Marc L., Parazoo, Nicholas, Brophy, Kieran, Cui, Xinguang, Jeong, Seongeun, Liu, Junjie, Keeling, Ralph, Taylor, Thomas E., Gurney, Kevin, Oda, Tomohiro, and Graven, Heather. Simulating estimation of California fossil fuel and biosphere carbon dioxide exchanges combining in situ tower and satellite column observations. United States: N. p., 2017. Web. doi:10.1002/2016JD025617.
Fischer, Marc L., Parazoo, Nicholas, Brophy, Kieran, Cui, Xinguang, Jeong, Seongeun, Liu, Junjie, Keeling, Ralph, Taylor, Thomas E., Gurney, Kevin, Oda, Tomohiro, & Graven, Heather. Simulating estimation of California fossil fuel and biosphere carbon dioxide exchanges combining in situ tower and satellite column observations. United States. doi:10.1002/2016JD025617.
Fischer, Marc L., Parazoo, Nicholas, Brophy, Kieran, Cui, Xinguang, Jeong, Seongeun, Liu, Junjie, Keeling, Ralph, Taylor, Thomas E., Gurney, Kevin, Oda, Tomohiro, and Graven, Heather. Thu . "Simulating estimation of California fossil fuel and biosphere carbon dioxide exchanges combining in situ tower and satellite column observations". United States. doi:10.1002/2016JD025617. https://www.osti.gov/servlets/purl/1364604.
@article{osti_1364604,
title = {Simulating estimation of California fossil fuel and biosphere carbon dioxide exchanges combining in situ tower and satellite column observations},
author = {Fischer, Marc L. and Parazoo, Nicholas and Brophy, Kieran and Cui, Xinguang and Jeong, Seongeun and Liu, Junjie and Keeling, Ralph and Taylor, Thomas E. and Gurney, Kevin and Oda, Tomohiro and Graven, Heather},
abstractNote = {Here, we report simulation experiments estimating the uncertainties in California regional fossil fuel and biosphere CO2 exchanges that might be obtained by using an atmospheric inverse modeling system driven by the combination of ground-based observations of radiocarbon and total CO2, together with column-mean CO2 observations from NASA's Orbiting Carbon Observatory (OCO-2). The work includes an initial examination of statistical uncertainties in prior models for CO2 exchange, in radiocarbon-based fossil fuel CO2 measurements, in OCO-2 measurements, and in a regional atmospheric transport modeling system. Using these nominal assumptions for measurement and model uncertainties, we find that flask measurements of radiocarbon and total CO2 at 10 towers can be used to distinguish between different fossil fuel emission data products for major urban regions of California. We then show that the combination of flask and OCO-2 observations yields posterior uncertainties in monthly-mean fossil fuel emissions of ~5–10%, levels likely useful for policy relevant evaluation of bottom-up fossil fuel emission estimates. Similarly, we find that inversions yield uncertainties in monthly biosphere CO2 exchange of ~6%–12%, depending on season, providing useful information on net carbon uptake in California's forests and agricultural lands. Finally, initial sensitivity analysis suggests that obtaining the above results requires control of systematic biases below approximately 0.5 ppm, placing requirements on accuracy of the atmospheric measurements, background subtraction, and atmospheric transport modeling.},
doi = {10.1002/2016JD025617},
journal = {Journal of Geophysical Research: Atmospheres},
number = 6,
volume = 122,
place = {United States},
year = {Thu Mar 09 00:00:00 EST 2017},
month = {Thu Mar 09 00:00:00 EST 2017}
}

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  • Characterizing flow patterns and mixing of fossil fuel-derived CO{sub 2} is important for effectively using atmospheric measurements to constrain emissions inventories. Here we used measurements and a model of atmospheric radiocarbon ({sup 14}C) to investigate the distribution and fluxes of atmospheric fossil fuel CO{sub 2} across the state of California. We sampled {sup 14}C in annual C{sub 3} grasses at 128 sites and used these measurements to test a regional model that simulated anthropogenic and ecosystem CO{sub 2} fluxes, transport in the atmosphere, and the resulting {sup 14}C of annual grasses ({Delta}{sub g}). Average measured {Delta}{sub g} in Los Angeles,more » San Francisco, the Central Valley, and the North Coast were 27.7 {+-} 20.0, 44.0 {+-} 10.9, 48.7 {+-} 1.9, and 59.9 {+-} 2.5{per_thousand}, respectively, during the 2004-2005 growing season. Model predictions reproduced regional patterns reasonably well, with estimates of 27.6 {+-} 2.4, 39.4 {+-} 3.9, 46.8 {+-} 3.0, and 59.3 {+-} 0.2{per_thousand} for these same regions and corresponding to fossil fuel CO{sub 2} mixing ratios (Cf) of 13.7, 6.1, 4.8, and 0.3 ppm. {Delta}{sub g} spatial heterogeneity in Los Angeles and San Francisco was higher in the measurements than in the predictions, probably from insufficient spatial resolution in the fossil fuel inventories (e.g., freeways are not explicitly included) and transport (e.g., within valleys). We used the model to predict monthly and annual transport patterns of fossil fuel-derived CO{sub 2} within and out of California. Fossil fuel CO{sub 2} emitted in Los Angeles and San Francisco was predicted to move into the Central Valley, raising Cf above that expected from local emissions alone. Annually, about 21, 39, 35, and 5% of fossil fuel emissions leave the California airspace to the north, east, south, and west, respectively, with large seasonal variations in the proportions. Positive correlations between westward fluxes and Santa Ana wind conditions were observed. The southward fluxes over the Pacific Ocean were maintained in a relatively coherent flow within the marine boundary layer, while the eastward fluxes were more vertically dispersed. Our results indicate that state and continental scale atmospheric inversions need to consider areas where concentration measurements are sparse (e.g., over the ocean to the south and west of California), transport within and across the marine boundary layer, and terrestrial boundary layer dynamics. Measurements of {Delta}{sub g} can be very useful in constraining these estimates.« less
  • Abstract not provided.
  • The estimation of the rate of net CO{sub 2} uptake of vegetated land surfaces is essential for studies of global carbon cycle. The present paper demonstrates the use of spectral reflectance data from satellite remote sensing to model net CO{sub 2} flux (NCF) of a tallgrass canopy at the Konza prairie, Kansas. A bidirectional reflectance canopy model was used to estimate seasonal changes in canopy leaf area index (LAI) from surface reflectances remotely sensed by SPOT 1 and Landsat 5 satellites. The radiation model was also coupled with leaf conductance-photosynthesis models to scale up stomatal conductance and NCF from individualmore » leaves to canopy level according to radiation distribution inside the canopy. The satellite-data-driven model was able to closely simulate the seasonal change in LAI as well as the short-term variation of canopy LAI caused by the dry period during late July and early August in the area. Modeled canopy stomatal conductance (g{sub c}) and NCF agree with measurements within 0.16 cm s{sup {minus}1} and 0.28 mg m{sup {minus}2} s{sup {minus}1}, and respectively, during the growth season from late May to late August. In October both measured and modeled NCF turned to small negative values as canopy photosynthesis diminished and predicted LAI approached zero. In addition to data scatter, some of the differences between modeled and measured g{sub c} and NCF may be attributed to uncertainties in seasonal changes of plant physiological status that were not detected by satellite data; some of the differences were caused by inadequate description of the dependence of nighttime CO{sub 2} flux of soil respiration on near-surface turbulent mixing. 49 refs., 5 figs., 2 tabs.« less
  • In the original paper a mistake in Figure 11 occurred. The corrected version of the figure is provided.