12.1 How much benefit could there be from knowing transfer velocities more accurately?

Thursday, 23 August 2007: 1:30 PM
Broadway-Weidler-Halsey (DoubleTree by Hilton Portland)
Barry J. Huebert, Univ. of Hawaii, Honolulu, HI

If we could measure (and then model) hourly air/sea gas fluxes to within 10%, what would we know better? Anything? “We need better measurements” is a kind of a mantra, but what specific parts of the climate problem could be derived with greater confidence? Certainly studies of flux controlling factors would benefit from having more accurate flux measurements.

Would we be able to constrain the ocean's 2 GtC/yr net uptake of CO2 (the difference between emissions of 90 GtC/yr and uptake of 92 GtC/yr) any better? To say “the net CO2 uptake is 2 ±0.5 GtC/yr” requires that the uptake and emission be known to within 0.26%, about two orders of magnitude better than we can do now in any region. We will probably never know exchange velocities to ±5%, yet using more accurate formulations for modeling both the emissions and the uptake might still reduce the error in the difference considerably. Now many authors compute regional fluxes using two different models (often Wanninkhof and Liss and Merlivat), and present both results in the same table! Thus, any uncertainty less than a factor of two will constrain budget computations much better than can be done at present.

However, if the net loss of atmospheric CO2 is controlled largely by how fast physical or biological carbon pumps operate, are there any areas where the exchange coefficient is the factor limiting a major part of the carbon cycle? Do interfacial C-exchange and C-burial essentially operate as serial resistances? In what circumstances would an improvement in our understanding of exchange velocities (as opposed to carbon pumps) improve long-term C uptake estimates?

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