7th International Symposium on Gas Transfer at Water Surfaces

Abstract

The 7th International Symposium on Gas Transfer at Water Surfaces was held 18-21 May 2015 in Seattle, Washington. These symposia, which have occurred approximately every five years since 1983, bring together the international scientific and engineering community investigating the mechanisms, parameterizations, and applications of gas transfer at water surfaces. The focus in part is on the physical processes that govern the gas flux, which include air entrainment (by breaking waves, flow over hydraulic structures, or direct injection), turbulence (generated by mechanical agitation, wind, wave breaking, rainfall, or currents), and the effect of natural and synthetic surfactants. Of equal importance to the treatment of the forcing mechanisms are the discussions on how to model or parameterize air-water gas transfer relevant to biogeochemical cycling on global, regional, and local scales. Furthermore, because the mechanisms controlling the gas flux also govern the air-sea flux of heat and momentum, the conference is attended by many studying a wide range of air- and water-side mixing processes that occur at or near the ocean surface. This provides opportunities for crossfertilization of ideas between the classical air-sea interaction community and those focused on biogeochemical cycling.The first symposium was held at Cornell University, Ithaca, New York in 1983 [1]. The second symposium took place in Minneapolis in 1990 [2] and the third symposium was held at the University of Heidelberg in Heidelberg, Germany in 1995 [3]. The fourth symposium took place in Miami in 2000 [4] and the fifth symposium was held in Liège, Belgium in 2005 in conjunction with the 37th International Liège Colloquium on Ocean Dynamics [5]. The sixth symposium was held in Kyoto, Japan in 2010 [6].Gas transfer at air-water interfaces encompasses a wide variety of research, including fundamental fluid dynamics, biogeochemistry, and oceanography across a range of spatial and temporal scales. For example, the exchange of greenhouse gases between the atmosphere and natural bodies of water is critical to characterize and quantify global climate change. The establishment of a regular series of international symposia with a periodicity of five years was motivated by the increasing societal interest in the consequences of gas transfer at air-water interfaces, the size and productivity of the research community, and the wide geographic distribution of active researchers. The symposium has established a reputation as an important and influential venue for presenting and disseminating research progress to the community. The five-year period between gatherings ensures that significant progress since the last occurrence will be reported.The research problems involve extremely challenging and complex issues associated with turbulent flow over a wide range of spatial and temporal scales that include the effects of wind and currents, breaking waves, rainfall, and two-phase flow effects due to the presence of bubbles generated by breaking waves and raindrops. The complexity is increased by the occurrence of both natural and anthropogenic surface films, which can modify the chemical and physical characteristics of the interface. The challenge of understanding gas transfer and the effect of gas exchange on biogeochemistry has led to the need for multidisciplinary, collaborative efforts and the development of a wide variety of innovative observational and experimental techniques. As many dedicated past attendees can attest, the symposia have fostered productive and long-lasting collaborations that have made new and pivotal contributions over the past three decades.