| Summary: | Observational and modeling studies are conducted to explore the changing physical environment of the western Arctic Ocean and its significance to upper-ocean hydrography and acoustic energy propagation. In-situ observations of temperature and salinity were made as part of the Canada Basin Acoustic Propagation Experiment (CANAPE) pilot study in summer 2015. Sound-speed fluctuations due to internal waves and spice were analyzed to describe spatio-temporal variability. Internal-wave frequency spectra show a spectral slope lower than the Garrett-Munk (GM) model, and the energy level is 4% of the standard GM value. Frequency spectra of spice show a form similar to the internal-wave spectra but with a steeper spectral slope. Several global climate models were evaluated against historical and recent hydrographic observations and found to inadequately represent key upper-ocean hydrographic features. The Regional Arctic System Model (RASM) was used to investigate sensitivity of the simulated upper ocean to various configurations and showed that sub-grid scale brine rejection parameterization, appropriately tuned surface momentum coupling, and increased vertical and horizontal resolution improved model simulation. In both observational and model data sets, a near-surface sound channel is present, the significance and variability of which warrant further in-situ investigations and model improvements. Approved for public release; distribution is unlimited. Lieutenant Commander, United States Navy http://archive.org/details/observationsndmo1094551680
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