Multiple dipole eddies in the Alaska Coastal Current detected with Landsat thematic mapper data

Abstract

Seventeen dipole eddies, including five large, well-formed ones, three second-generation eddies, and two double eddies, were observed in the Alaska Coastal Current near Kayak Island in one single scene of the Landsat thematic mapper (TM) on April 22, 1985. The digital Landsat TM satellite data were computer analyzed to extract details in the near coastal circulation in the northern Gulf of Alaska. Enhancement techniques were applied to the visible and thermal IR bands. The features are evident only in the visible bands because of the ability of these bands to detect the distribution of sediments in the near surface. These eddies did not have a significant thermal signature. The sources of these sediments are the glacial streams found throughout the Gulf of Alaska coast. Eddies of this configuration and frequency have never been observed here previously. However, the oceanographic and meteorological conditions are typical for this time of year. These eddies should be important to the cross-shelf mixing processes in the Alaska Coastal Current and are an indicator that the flow here can be unstable at certain times of the year. 13,041 13,042 AHLN•S ET AL.' MULTIPLE DIPOLE EDDIES IN ALASKA COASTAL CURRENT

Physical variability in Prince William Sound during the SEA Study (1994–98)

“…Dynamic heights (Niebauer et al. , 1994) and satellite colour images (Ahlnas et al. , 1987) suggest weak and variable flow for the shelf region between Montague Island (Fig.…”

Larval fish habitats in a mesoscale dipole eddy in the gulf of California

“…Such mushroom-shaped eddy pairs have been detected using satellite imagery (Ikeda and Emery, 1984;Millot ,1987;Ahlnäs et al, 1987;Lavín et al, 2009;Meunier et al, 2012); and by numerical models (Federov and Ginzburg, 1986;Etling et al, 1993;Sutyrin et al, 2008). The in situ studies of Simpson and Lynn (1990) and de Ruijter et al (2004) described dipoles using hydrographic data off Southern California and South Madagascar, respectively.…”

Three-Dimensional Mesoscale Dipole Frontal Collisions

“…Vortex dipoles have been observed in many places in the ocean (e.g., Fedorov and Ginzburg 1986;Munk et al 1987), including the Alaska Coastal Current (Ahlnäs et al 1987), along the Vancouver Island coast (Ikeda et al 1984), along the California coast (Sheres and Kenyon 1989;Simpson and Lynn 1990), south of Madagascar (de Ruijter et al 2004), in Tartar Strait (Ginzburg and Fedorov 1984), in the Norwegian Coastal Current (Johannessen et al 1989), and in the Oyashio Front (east of Japan; Vastano and Bernstein 1984).…”