These observations were critical in determining the depth and horizontal extent of each significant eddy. Tidal fluctuations and meteorological conditions were the largest sources of variability impacting the tactical acoustic environment. Persistent trade winds provided the mechanical mixing of the surface layer down to depths of ≈50m. However, in ″wind shadow″ areas behind mountainous islands or during periods of low wind speeds, a strong diurnal ″surface cap″ of very warm water formed that ″disguised″ an eddy's inner core characteristics. NCOM did a fairly good job of capturing this variability once observations began to be assimilated. In contrast, the acoustics application module had a harder time capturing the sharp sub-surface temperature gradient sometimes showing much deeper sonic layer depths than actually existed due to the peculiarity of the embedded sound speed algorithm.
We will discuss NCOM model performance, the impact of the deep sea glider observations and the role of the operational ocean forecaster in providing an appropriate tactical assessment to our warfighter customer.