The Haida eddies are a group of mesoscale, anticyclonic eddies that form off the coast of the Queen Charlotte Islands in the winter months. These eddies transport coastal water, which contain high metal and nutrient concentrations, westward into the Alaskan gyre. The Alaskan gyre is considered a high nutrient, low chlorophyll region where primary production is limited by iron. The Haida eddies may be a form of iron introduction to this system that was previously overlooked. The study of these eddies also gives us a chance to study coastal water as it ages, since there is limited interaction with surrounding waters. This allows for calculation of removal rates of trace metals.
The Haida eddy study is in collaboration with the Institute of Ocean Sciences, Sidney, BC. Sampling cruises occurred in June and September 2000 and 2001 (with limited sampling in February). The eddies were tracked by means of satellite altimetry. They have a positive sea surface height anomaly since their density is lower than the surrounding open ocean water. Below is a typical SSH anomaly plot of September 2001 (courtesy of the Colorado Center for Astrodynamics Research). The red circle indicates the Haida 2001 eddy.
In April 2001, a large dust storm originating in the Gobi and Takla Makan deserts resulted in large quantities of dust to be transported to the northeastern Pacific Ocean (satellite image below). The most concentrated plume of dust traveled toward the eastern Gulf of Alaska, depositing dust in the region of the Haida eddies. The presence of dust remnants held within a quasi-isolated mesoscale eddy allows us to draw conclusions about succession following dust deposition events and yields further information regarding interactions between trace metal supply and primary production in the NE Subarctic Pacific.
This plot represents absorbing aerosol particles (airborne microscopic dust/smoke). The higher the index, the larger the number of particles in the air.