Identification of acoustically active Arctic pressure ridges through the use of RADARSAT Geophysical Processor System (RGPS) sea ice products

Abstract

The identification of acoustically active pressure ridges in the Arctic Ocean represents an important step in the development of a physics based, operational Polar ambient noise model. One method to accomplish this goal is through the use of satellite based remote sensors, specifically synthetic aperture radar (SAR). A proof of concept study was conducted that determined that the RADARSAT Geophysical Processor System (RGPS) produces SAR derived sea ice products capable of quantifying large scale ice deformation that may produce significant levels of low frequency ambient noise. This research also identifies the meteorological forcing that causes the sequence of divergent and convergent events in the ice cover, which results in the creation of open water leads and subsequent generation of noisy pressure ridges. Offshore followed by onshore winds near coasts and land fast ice and atmospheric lows/troughs followed by atmospheric highs/ridges or velocity shear in straight isobaric flow result in significant pressure ridge formation. The RGPS ridging algorithm shows that more ridges exist in RGPS cells exhibiting large cell area changes than in those with small area changes, assuming relatively constant cell heights in all cells. The feasibility of using ice divergence fields generated by Fleet Numerical Meteorology and Oceanography Center's (FNMOC's) Polar Ice Prediction System (PIPS) was evaluated. PIPS modeled ice divergence patterns reasonably well, although divergence values in the high Arctic ice cover were underestimated