Collaborative Research: Bubble Processes during Air-Sea Gas Transfer

University Of Washington, Seattle WA

Investigators

Abstract

Remote gas measurements by floats, gliders, and moorings are used to indirectly determine the Annual Net Community Production (ANCP) in the ocean by examining the gases produced by the biological community during photosynthesis and respiration (i.e. oxygen and carbon dioxide). In principal this method works well, but currently there is a great deal of uncertainty regarding the role of bubbles in the air-sea exchange of gases, and thus in altering the concentrations of gases important for ANCP calculations. This research aims to constrain the effects of bubbles on remote gas measurements used for these production estimates. In particular, oxygen, nitrogen, and carbon dioxide will be studied. By making measurements of these gases under storm conditions, the study will attempt to determine how much impact turbulence has on bubble processes and air-sea gas transfer. Data from the field observations will then be used to create a bubble process model which will help researchers more accurately use gas measurements to estimate how the biological signal (i.e. ANCP) is modified by physical processes (i.e. bubbles). One graduate student at Louisiana State University will be funded through this project, and the Program for Climate Change at the University of Washington will be supported through training of high school teachers on the role of the oceans in the earth's climate. Upper ocean turbulence has a significant effect on the air-sea transfer of gases. This effect is known, but currently not very well understood or constrained. In particular, the role of bubble processes in this exchange are largely a mystery and introduces a great deal of uncertainty into the use of oxygen measurements as proxies for Annual Net Community Production. This research plans to merge fieldwork and modeling methods to create mechanistic models that will allow researchers to more accurately quantify bubble processes as a mechanism for air-sea exchange of biogenic gases, thereby resulting in a more precise method to calculate Annual Net Community Production from remote sensors on floats, gliders, and moorings. By making precise measurements of O2, N2, and CO2 at the air-sea boundary before and after the rapid pressure changes during storm conditions, a better understanding of the these effects on the exchange of these gases between the surface ocean and lower atmosphere will be achieved.