Intellectual Merit: This project is a one-year study to measure turbulent buoyancy flux with an instrumented mast. These measurements will test whether it is possible to quantify turbulent buoyancy flux in energetic and highly stratified coastal environments. The study will be conducted in conjunction with an ongoing study in the Merrimack estuary and in the adjacent waters of the Gulf of Maine. In both areas the stratification is high and a control-volume approach has shown that the buoyancy flux is orders of magnitude greater than in almost any other oceanographic regime. The mast system will add direct estimates of buoyancy flux as well as measurements of stress and estimates of dissipation. There are risks associated with the physical implementation of the measurements and in the processing of the data. Surface waves affect operations in part because the heavy 10-meter mast changes how the vessel responds. In addition, the interference of the mast mostion and the wave motion may mask the signal of the turbulent motions. However, if this project is successful, this could provide a significant breakthrough in quantifying mixing in the coastal and estuarine ocean. Broader Impacts: This study will contribute to our understanding of mixing in the coastal ocean, which has implications for the transport and dispersal of pollutants as well as biogeochemical materials. In addition, this study will assist the ongoing field work of a new PI.
