Using a regional ocean model to understand the structure and sampling variability of acoustic thermometry measurements in Fram Strait

Florian Geyer1, Hanne Sagen1 and Bruce D Cornuelle2, (1)Nansen Environmental and Remote Sensing Center, Bergen, Norway, (2)University of California San Diego, Scripps Institution of Oceanography, La Jolla, United States
Abstract:
Data assimilation of 2-year dataset of acoustic thermometry observations in Fram Strait will make these observations easier to interpret for oceanographers and provide insight into the strong ocean variability of this important ocean region connecting the Atlantic and Arctic Ocean. A regional ocean model for Fram Strait allows to understand the variability and structure of acoustic arrivals from the acoustic thermometry experiment. The eddy-permitting model (52 vertical layers and 4.5 km horizontal resolution) was evaluated using long-term moored hydrography data and time series of depth-range averaged temperature obtained from the inversion of acoustic tomography measurements. Geometric ray modelling on the ocean model fields reproduces the measured arrival structure of the acoustic tomography experiment. The combination of ocean and acoustic model gives insights into acoustic propagation during winter and spring. The results of this study have implications for the inversion of acoustic thermometry data in Fram Strait. The increased knowledge about the ray-length variations of bottom-reflected rays is valuable information for choosing appropriate observation kernels for the data assimilation of acoustic thermometry data in Fram Strait.