Publications

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2009
Muhle, J, Huang J, Weiss RF, Prinn RG, Miller BR, Salameh PK, Harth CM, Fraser PJ, Porter LW, Greally BR, O'Doherty S, Simmonds PG.  2009.  Sulfuryl fluoride in the global atmosphere. Journal of Geophysical Research-Atmospheres. 114   10.1029/2008jd011162   AbstractWebsite

The first calibrated high-frequency, high-precision, in situ atmospheric and archived air measurements of the fumigant sulfuryl fluoride (SO(2)F(2)) have been made as part of the Advanced Global Atmospheric Gas Experiment (AGAGE) program. The global tropospheric background concentration of SO(2)F(2) has increased by 5 +/- 1% per year from similar to 0.3 ppt (parts per trillion, dry air mol fraction) in 1978 to similar to 1.35 ppt in May 2007 in the Southern Hemisphere, and from similar to 1.08 ppt in 1999 to similar to 1.53 ppt in May 2007 in the Northern Hemisphere. The SO(2)F(2) interhemispheric concentration ratio was 1.13 +/- 0.02 from 1999 to 2007. Two-dimensional 12-box model inversions yield global total and global oceanic uptake atmospheric lifetimes of 36 +/- 11 and 40 +/- 13 years, respectively, with hydrolysis in the ocean being the dominant sink, in good agreement with 35 +/- 14 years from a simple oceanic uptake calculation using transfer velocity and solubility. Modeled SO2F2 emissions rose from similar to 0.6 Gg/a in 1978 to similar to 1.9 Gg/a in 2007, but estimated industrial production exceeds these modeled emissions by an average of similar to 50%. This discrepancy cannot be explained with a hypothetical land sink in the model, suggesting that only similar to 2/3 of the manufactured SO(2)F(2) is actually emitted into the atmosphere and that similar to 1/3 may be destroyed during fumigation. With mean SO(2)F(2) tropospheric mixing ratios of similar to 1.4 ppt, its radiative forcing is small and it is probably an insignificant sulfur source to the stratosphere. However, with a high global warming potential similar to CFC-11, and likely increases in its future use, continued atmospheric monitoring of SO(2)F(2) is warranted.

2005
Nevison, CD, Keeling RF, Weiss RF, Popp BN, Jin X, Fraser PJ, Porter LW, Hess PG.  2005.  Southern Ocean ventilation inferred from seasonal cycles of atmospheric N2O and O2/N2 at Cape Grim, Tasmania. Tellus Series B-Chemical and Physical Meteorology. 57:218-229.   10.1111/j.1600-0889.2005.00143.x   AbstractWebsite

The seasonal cycle of atmospheric N(2)O is derived from a 10-yr observational record at Cape Grim, Tasmania (41 degrees S, 145 degrees E). After correcting for thermal and stratospheric influences, the observed atmospheric seasonal cycle is consistent with the seasonal outgassing of microbially produced N(2)O from the Southern Ocean, as predicted by an ocean biogeochemistry model coupled to an atmospheric transport model (ATM). The model-observation comparison suggests a Southern Ocean N(2)O source of similar to 0.9 Tg N yr(-1) and is the first study to reproduce observed atmospheric seasonal cycles in N(2)O using specified surface sources in forward ATM runs. However, these results are sensitive to the thermal and stratospheric corrections applied to the atmospheric N(2)O data. The correlation in subsurface waters between apparent oxygen utilization (AOU) and N(2)O production (approximated as the concentration in excess of atmospheric equilibrium Delta N(2)O) is exploited to infer the atmospheric seasonal cycle in O(2)/N(2) due to ventilation of O(2)-depleted subsurface waters. Subtracting this cycle from the observed, thermally corrected seasonal cycle in atmospheric O(2)/N(2) allows the residual O(2)/N(2) signal from surface net community production to be inferred. Because N(2)O is only produced in subsurface ocean waters, where it is correlated to O(2) consumption, atmospheric N(2)O observations provide a methodology for distinguishing the surface production and subsurface ventilation signals in atmospheric O(2)/N(2), which have previously been inseparable.

2004
Nevison, CD, Lueker TJ, Weiss RF.  2004.  Quantifying the nitrous oxide source from coastal upwelling. Global Biogeochemical Cycles. 18   10.1029/2003gb002110   AbstractWebsite

A continuous record of atmospheric N2O measured from a tower in northern California captures strong pulses of N2O released by coastal upwelling events. The atmospheric record offers a unique, observation-based method for quantifying the coastal N2O source. A coastal upwelling model is developed and compared to the constraints imposed by the atmospheric record in the Pacific Northwest coastal region. The upwelling model is based on Ekman theory and driven by high-resolution wind and SST data and by relationships between subsurface N2O and temperature. A simplified version of the upwelling model is extended to the world's major eastern boundary regions to estimate a total coastal upwelling source of similar to0.2 +/- >70% Tg N2O-N/yr. This flux represents similar to5% of the total ocean source, estimated here at similar to4 Tg N2O-N/yr using traditional gas-transfer methods, and is probably largely neglected in current N2O budgets.