Numerical simulation of remote acoustic sensing of ocean temperature in the Fram Strait environment

Abstract

An important part of the general problem of the Arctic climate change is the monitoring of the Fram Strait, which lies between Greenland and Spitsbergen. For this reason it is reasonable to apply acoustic methods which are proven to be effective in acoustic ocean thermometry, acoustic tomography, etc. Knowledge of the main peculiarities of sound signal propagation in this region is needed to estimate the feasibility of applying remote acoustic methods. To this end computer simulation of sound signal propagation in the Fram Strait environment was performed, based on oceanographic data obtained by the R/V POLARSTERN expedition. The presence of stable eigenrays in Fram Strait environmental conditions is demonstrated, typical values of acoustic signal travel time fluctuations due to environmental variations are determined, and the temperature effect on the signal travel time variation is considered. Sensitivity estimates for measurement of the average ocean temperature across Fram Strait is considered in two approaches: by calculating travel time changes along selected stable eigenrays, and by determining the cumulative sum of the whole envelope of the signals passed along water-borne paths.