Publications

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2003
Lueker, TJ, Walker SJ, Vollmer MK, Keeling RF, Nevison CD, Weiss RF, Garcia HE.  2003.  Coastal upwelling air-sea fluxes revealed in atmospheric observations of O2/N2, CO2 and N2O. Geophysical Research Letters. 30   10.1029/2002gl016615   AbstractWebsite

[1] We capture water column ventilation resulting from coastal upwelling in continuous records of O-2/N-2, CO2, and N2O at Trinidad, California. Our records reveal the gas exchange response time of the ocean to the upwelling and ensuing biological production. Satellite and buoy wind data allow extrapolation of our records to assess coastal upwelling air-sea fluxes of O-2 and N2O. We improve on previous regional estimates of N2O flux in coastal and continental shelf region of the western U. S. We characterize the source of N2O as being predominately from nitrification based on the O-2/N2O emissions ratio observed in our atmospheric records.

2002
Vollmer, MK, Weiss RF, Schlosser P, Williams RT.  2002.  Deep-water renewal in Lake Issyk-Kul. Geophysical Research Letters. 29   10.1029/2002gl014763   AbstractWebsite

[1] The deep-water renewal rates of Lake Issyk-Kul are studied using the time-dependent anthropogenically produced tracers sulfur hexafluoride (SF6), chlorofluorocarbons (CFCs) and tritium-helium-3. SF6 and the CFCs are used to calibrate a mixing model from which the vertical age distribution is calculated and found to be comparable to the SF6 apparent ages. Based on this model, the mean age of the water below 100 m depth is 6.1 yrs. The mean oxygen consumption rate for the same depth range is 6.4 m mol kg(-1) yr(-1) and the mean remineralization rates for nitrate, phosphate and silicate are 0.53, 0.003 and 0.67 m mol kg(-1) yr(-1), respectively.

1995
Nevison, CD, Weiss RF, Erickson DJ.  1995.  Global oceanic emissions of nitrous oxide. Journal of Geophysical Research-Oceans. 100:15809-15820.   10.1029/95jc00684   AbstractWebsite

The global N2O flux from the ocean to the atmosphere is calculated based on more than 60,000 expedition measurements of the N2O anomaly in surface water. The expedition data are extrapolated globally and coupled to daily air-sea gas transfer coefficients modeled at 2.8 degrees x 2.8 degrees resolution to estimate a global ocean source of about 4 (1.2-6.8) Tg N yr(-1). The wide range of uncertainty in the source estimate arises mainly from uncertainties in the air-sea gas transfer coefficients and in the global extrapolation of the summertime-biased surface N2O data set. The strongest source is predicted from the 40-60 degrees S latitude band. Strong emissions also are predicted from the northern Pacific Ocean, the equatorial upwelling zone, and coastal upwelling zones occurring predominantly in the tropical northern hemisphere. High apparent oxygen utilization (AOU) at 100 m below the mixed layer is found to be correlated positively both to N2O production at depth and to the surface N2O anomaly. On the basis of these correlations, the expedition data are partitioned into two subsets associated with high and low AOU at depth. The zonally averaged monthly means in each subset are extrapolated to produce two latitude-by-month matrices in which monthly surface N2O is expressed as the deviation from the annual mean. Both matrices contain large uncertainties. The low-AOU matrix, which mainly includes surface N2O data from the North Atlantic and the subtropical gyres, suggests many regions with positive summer deviations and negative winter deviations, consistent with a seasonal cycle predominantly driven by seasonal heating and cooling of the surface ocean. The high-AOU subset, which includes the regions most important to the global N2O ocean source, suggests some regions with positive winter deviations and negative summer deviations, consistent with a seasonal cycle predominantly driven by wintertime mixing of surface water with N2O-rich deep water. Coupled seasonal changes in gas transfer coefficients and surface N2O in these important source regions could strongly influence the global ocean source.