Andrew Cookson, Eric Boget, and Matthew Alford, together with graduate student Kim Martini and postdoc Zhongxiang Zhao, just completed a major field experiment north of Hawaii. In two cruises totaling 50 days on R/V Roger Revelle from April through June 2006, we collected data that we hope will allow us to unravel some of the processes that befall the "internal tide," a large underwater disturbance that is generated at the Hawaiian Ridge and travels at least 1000-2000 km northward. Because it carries a substantial amount of energy, knowing where it "breaks" (in analogy with surface waves seen breaking on beaches) is important for improving models of the Earth's climate.

Internal Waves Across the Pacific (IWAP) is a $2.6M NSF-funded collaborative project with several Scripps researchers - Drs. Jennifer Mackinnon, Kraig Winters (both formerly at APL-UW), Walter Munk, and Rob Pinkel. The experiment's name is in honor of Walter's 60-year old result "Waves Across the Pacific," where he showed that the surface waves we see on beaches have likewise traveled all the way across ocean basins.

To measure the travel of the internal tide over these large distances, we used a combination of techniques. The backbone of the experiment was six moorings (picture 1, red dots) aligned with Hawaii's strongest "beam" of tidal energy flux (arrows), which emanates from French Frigate Shoals, a shallow ridge northwest of the beautiful Hawaiian Islands. Each mooring consisted of a McLane moored profiler, which crawls up and down the mooring wire between 80-1400 meters beneath the surface each hour and a half, measuring temperature, salinity, and velocity. ADCPs, Anderaa current meters, and Sea-bird temperature loggers were also used to capture the shallower and deeper signals. Many of these instruments were borrowed from other PI's, and we owe them a great debt of gratitude for their generosity.