A warm jet in a cold ocean.

Unprecedented quantities of heat are entering the Pacific sector of the Arctic Ocean through Bering Strait, particularly during summer months. Though some heat is lost to the atmosphere during autumn cooling, a significant fraction of the incoming warm, salty water subducts (dives beneath) below a cooler fresher layer of near-surface water, subsequently extending hundreds of kilometers into the Beaufort Gyre. Upward turbulent mixing of these sub-surface pockets of heat is likely accelerating sea ice melt in the region.

The formation and fate of internal waves in the South China Sea.

Internal gravity waves, the subsurface analogue of the familiar surface gravity waves that break on beaches, are ubiquitous in the ocean. Because of their strong vertical and horizontal currents, and the turbulent mixing caused by their breaking, they affect a panoply of ocean processes, such as the supply of nutrients for photosynthesis, sediment and pollutant transport and acoustic transmission; they also pose hazards for man-made structures in the ocean. Generated primarily by the wind and the tides, internal waves can travel thousands of kilometres from their sources before breaking, making it challenging to observe them and to include them in numerical climate models, which are sensitive to their effects.

Field measurements and modeling of attenuation from near-surface bubbles for frequencies 1-20 kHz.

Measurements of excess attenuation from near-surface bubbles from the Shallow Water '06 experiment are reported. These are transmission measurements made over the frequency range 1-20 kHz, and they demonstrate a frequency, grazing angle, and wind speed dependence in attenuation. Data modeling points to bubble void fractions of order 10(-6) in effect for wind speeds 10-13 m/s.