APL Seminar: "What can chemistry do for you (the Arctic edition)?", Alkire (OSU)

Start Date/Time: Tuesday, November 24, 2009, 10:00 AM
Location: Hardisty Conference Center

Title: "What can chemistry do for you (the Arctic edition)?"
Presenter: Matt Alkire College of Oceanic & Atmospheric Sciences, Oregon State University

There are numerous freshwater inputs to the Arctic Ocean, including river runoff from both North American and Eurasian continents, sea-ice meltwater, and Pacific inflow through Bering Strait. This diversity in low-salinity inputs, combined with predominately low temperatures, demands chemical tracers able to identify various water types otherwise indistinguishable using temperature and salinity alone. The quasi-conservative NO parameter (NO = 9 x [NO3] + [O2]) is an example of one such tool. A pronounced vertical minimum in NO has classically been associated with relatively saline (34.2 â≈€ S â≈€ 34.5) water of Atlantic origin ventilating the Arctic halocline. The first in-situ, sensor-based measurements of nitrate (NO3) were collected from the central Arctic Ocean and southern Canada Basin during spring 2007 and 2008 thanks to an expanded effort of the North Pole Environmental Observatory in the International Polar Year. These data were combined with in-situ dissolved oxygen (O2) profiles to derive the first continuous vertical profiles of NO in the Arctic Ocean. These new, high-resolution measurements of NO reveal complex structure within the halocline of the central Arctic. One such example includes the presence of NO minima at salinities < 34.0 in the Makarov Basin. A somewhat larger contribution of Eurasian river runoff (relative to the Amundsen Basin) was coincident with these less saline NO minima. These observations might be linked as a consequence of the effect of wind forcing on offshore versus alongshore advection of Siberian shelf waters during recent years. In the southern Canada Basin, numerous inputs to the lower halocline (34.2 â≈€ S â≈€ 34.5) were suggested, including brine formation associated with polynyas, a mechanism which has recently come under debate.

Location: Hardisty Conference Center- Use the east entrance of Henderson Hall and ask the receptionist for directions to the Conference Center.