SAR observing large-scale nonlinear internal waves in the White Sea

- The SW Gorlo Strait is a major hotpoint for generation of nonlinear internal waves.
- Short internal waves evolve into large-scale packets crossing the sea.
- Internal waves strongly impact the vertical mixing and hydrology of shelf areas.

The compiled archive of synthetic aperture radar (SAR) images acquired by the Advanced SAR (ASAR) onboard the Envisat satellite over the White Sea during the extended summer periods (May-September) between 2007 and 2011, provides the first detailed analysis of 2-D patterns of internal waves (IWs) in the White Sea. Unambiguously, the primary region of IW activity is the southwestern (SW) Gorlo Strait (GS). IW packets emerging from this area are regularly observed to reach crest lengths up to 200 km, and also to propagate a few hundred kilometers from their origin. Model results confirm that large-scale IWs can be generated every tidal cycle and are able to cross the entire sea. As suggested, the source of these packets is governed by the intense dynamics of the frontal zone in the tidal cycle over local complex bottom. As further revealed, these large-scale IWs cascade into intense large-amplitude short IW packets on the shoaling White Sea shelf, significantly impacting vertical turbulent exchange and the overall hydrology.