Characterization of air-sea gas exchange processes and dissolved gas/ice interactions using noble gases
In order to constrain the processes controlling the cycles of biogeochemically important gases such as 02 and C02, and thereby infer rates of biological activity in the upper ocean or the uptake of radiatively important "greenhouse" gases, the noble gases are used to characterize and quantify the physical processes affecting the dissolved gases in aquatic environments. The processes of vertical mixing, gas exchange, air injection, and radiative heating are investigated using a 2 year time-series of the noble gases, temperature, and meteorological data from Station S near Bermuda, coupled with a 1- dimensional upper ocean mixing model to simulate the physical processes in the upper ocean. The rate of vertical mixing that best simulates the thermal cycle is 1.1±0.1 x104 m The gas exchange rate required to simulate the data is consistent with the formulation of Wanninkhof (1992) to ± 40%, while the formulation of Liss and Merlivat 1986 must be increased by a factor of 1.7± 0.6. The air injection rate is consistent with the formulation of Monahan and Torgersen (1991) using an air entrainment velocity of 3±1 cm s1. Gas flux from bubbles is dominated on yearly time-scales by larger bubbles that do not dissolve completely, while the bubble flux is dominated by complete dissolution of bubbles in the winter at Bermuda. In order to obtain a high-frequency time-series of the noble gases to better parameterize the gas flux from bubbles, a moorable, sequential noble gas sampler was developed. Preliminary results indicate that the sampler is capable of obtaining the necessary data. Dissolved gas concentrations can be significantly modified by ice formation and melting, and due to the solubility of He and Ne in ice, the noble gases are shown to be unique tracers of these interactions. A three-phase equilibrium partitioning model was constructed to quantify these interactions in perennially ice-covered Lake Fryxell, and this work was extended to oceanic environments. Preliminary surveys indicate that the noble gases may provide useful and unique information about interactions between water and ice.
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution September 1997
Showing items related by title, author, creator and subject.
FASINEX Frontal Air-Sea Interaction Experiment (January-June 1986) : summaries for FASINEX mooring cruises; phase one: R/V KNORR Cruise 119, phase three: RV/KNORR Cruise 123 Pennington, Nancy J.; Weller, Robert A. (Woods Hole Oceanographic Institution, 1986-10)The Frontal Air-Sea Interaction Experiment (FASINEX) was a study of the response of the upper ocean to atmospheric forcing in the vicinity of an oceanic front in the subtropical convergence zone southwest of Bermuda, the ...
FASINEX Frontal Air-Sea Interaction Experiment (January-June 1986) : cruise summaries for FASINEX phase two; R/V OCEANUS cruise 175, R/V ENDEAVOR cruise 141 Pennington, Nancy J.; Weller, Robert A. (Woods Hole Oceanographic Institution, 1986-10)The Frontal Air-Sea Interaction Experiment (FASINEX) was a study of the response of the upper ocean to atmospheric forcing in the vicinity of an oceanic front in the subtropical convergence zone southwest of Bermuda, ...
Cosmogenic ³²P and ³³P in the atmosphere and aligotrophic ocean and applications to the study of phosphorus cycling Waser, Nathalie A. D. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1992-11)Cosmogeruc P-32 (14.28 days) and P-33 (25.3 days) are powerful tracers of upper ocean P cycling, when coupled with time-series of the atmospheric sources. A method was developed to determine the low-level beta activities ...