Bibliography - Jasmin John

1. Baker, D F., R M Law, K R Gurney, P Rayner, P Peylin, A S Denning, P Bousquet, L Bruhwiler, Y-H Chen, P Ciais, I Y Fung, M Heimann, Jasmin John, T Maki, S Maksyutov, K Masarie, M J Prather, B Pak, S Taguchi, and Z Zhu, 2006: TransCom 3 inversion intercomparison: Impact of transport model errors on the interannual variability of regional CO2 fluxes, 1988–2003. Global Biogeochemical Cycles, 20, GB1002, doi:10.1029/2004GB002439.
   [ Abstract ]

   Monthly CO2 fluxes are estimated across 1988–2003 for 22 emission regions using data from 78 CO2 measurement sites. The same inversion (method, priors, data) is performed with 13 different atmospheric transport models, and the spread in the results is taken as a measure of transport model error. Interannual variability (IAV) in the winds is not modeled, so any IAV in the measurements is attributed to IAV in the fluxes. When both this transport error and the random estimation errors are considered, the flux IAV obtained is statistically significant at P ≤ 0.05 when the fluxes are grouped into land and ocean components for three broad latitude bands, but is much less so when grouped into continents and basins. The transport errors have the largest impact in the extratropical northern latitudes. A third of the 22 emission regions have significant IAV, including the Tropical East Pacific (with physically plausible uptake/release across the 1997–2000 El Niño/La Niña) and Tropical Asia (with strong release in 1997/1998 coinciding with large-scale fires there). Most of the global IAV is attributed robustly to the tropical/southern land biosphere, including both the large release during the 1997/1998 El Niño and the post-Pinatubo uptake

2. Gurney, K R., A Lauer, A S Denning, P Rayner, D F Baker, P Bousquet, L Bruhwiler, Y-H Chen, P Ciais, Song-Miao Fan, I Y Fung, M Gloor, M Heimann, K Higuchi, Jasmin John, E Kowalczyk, T Maki, S Maksyutov, P Peylin, M J Prather, B Pak, Jorge L Sarmiento, S Taguchi, T Takahashi, and C-W Yuen, 2003: TransCom 3 CO2 inversion intercomparison: 1. Annual mean control results and sensitivity to transport and prior flux information. Tellus B, 55B(2), 555-579.
   [ Abstract PDF ]

   Spatial and temporal variations of atmospheric CO₂ concentration contain information about surface sources and sinks, which can be quantitatively interpreted through tracer transport inversion. Previous CO₂ inversion calculations obtained differing results due to different data, methods and transport models used. To isolate the sources of uncertainty, we have conducted a set of annual mean inversion experiments in which 17 different transport models or model variants were used to calculate regional carbon sources and sinks from the same data with a standardized method. Simulated transport is a significant source of uncertainty in these calculations, particularly in the response to prescribed "background" fluxes due to fossil fuel combustion, a balanced terrestrial biosphere, and air-sea gas exchange. Individual model-estimated fluxes are often a direct reflection of their response to these background fluxes. Models that generate strong surface maxima near background exchange locations tend to require larger uptake near those locations. Models with weak surface maxima tend to have less uptake in those same regions but may infer small sources downwind. In some cases, individual model flux estimates cannot be analyzed through simple relationships to background flux responses but are likely due to local transport differences or particular responses at individual CO₂ observing locations. The response to the background biosphere exchange generates the greatest variation in the estimated fluxes, particularly over land in the Northern Hemisphere. More observational data in the tropical regions may help in both lowering the uncertain tropical land flux uncertainties and constraining the northern land estimates because of compensation between these two broad regions in the inversion. More optimistically, examination of the model-mean retrieved fluxes indicates a general insensitivity to the prior fluxes and the prior flux uncertainties. Less uptake in the Southern Ocean than implied by oceanographic observations, and an evenly distributed northern land sink, remain in spite of changes in this aspect of the inversion setup.

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