Upcoming Events
Brown-Bag Lunch Hour Seminar: Internal Tides and Mixing on the Oregon Continental Slope Kim Martini
Heat and Freshwater Controlling Processes on the Northern Gulf of Alaska Shelf
Friday, 13 November, 1:00 pmMarkus Janout, Ph.D. Oceanography Degree Candidate
School of Fisheries and Ocean Sciences
Faculty Advisor: Dr. Tom Weingartner
Fairbanks—201 Vera Alexander Learning Center • Seward—101 Rae Building • Juneau—101 Lena Point • Anchorage—GHH 101 UAA
*Other sites available upon request to Madeline Scholl
Abstract:
We present results from the examination of processes that control the distribution of heat and freshwater on the northern Gulf of Alaska (GOA) shelf. In particular, we discuss the role of anticyclonic GOA eddies and the dynamics that led to the recent GOA cooling, and discuss the mechanisms that control temperatures on the GOA shelf.
We found that the outer shelf is subjected to cross-shelf freshwater transport under the impact of large (~200 km) anticyclonic eddies that form in the eastern GOA and propagate along the continental slope. These eddies are among the longest-lived (~5 years) oceanic eddies in the global ocean, and are significant biological hot sports in the high-nutrient-low-chlorophyll GOA basin. Additionally, the inner and middle shelves are governed by the seasonality of coastal freshwater runoff, which forces the Alaska Coastal Current and controls water column stability and deep ocean temperatures on this shelf. We examined the recent shift in ocean temperatures on the northern GOA shelf and concluded that the cooling was initiated by strong air-sea heat loss, low freshwater runoff and a reduction in along-shore heat transport. We also estimated that the ACC may re-supply the northern GOA with 10-35% of the heat removed by the atmosphere, highlighting its importance as an advective pathway for heat and freshwater.