Matt Alkire is currently involved in research projects at the Polar Science Center and the Ocean Physics Department. His research interests include: (1) the use of chemical tracers (salinity, δ18O, total alkalinity, barium, nutrients, and oxygen) to differentiate sources of freshwater (meteoric water, sea-ice meltwater, and Pacific water) in the Arctic Ocean and study changes in their distribution over time; (2) the evolution of these tracers in response to on-going Arctic change (e.g., warming, loss of sea ice, increased biological activity); (3) the linkages between changes in the surface circulation of the Arctic Ocean and the flux and composition of freshwater exported through the Canadian Arctic Archipelago and Nares Strait; and (4) the use of autonomous platforms (Lagrangian floats and Seagliders) to study biogeochemical dynamics and net community production on relatively small (mesoscale and sub-mesoscale) spatial and temporal scales.
Matt’s current research involves the use of chemical sensors to measure nitrate (NO3-) and dissolved oxygen (O2) in the central Arctic Ocean. These high-resolution profiles yield detailed information that cannot be achieved using standard bottle sampling techniques. The combination of these NO3 and O2 measurements allows the calculation of the tracer, “NO”, that can be used to study changes in the formation and distribution of dense waters formed on the broad continental shelves. These shelf waters play important roles in the ventilation of the halocline layer that separates the cold, polar mixed layer and sea ice cover from the warmer Atlantic waters at depth.
APL-Ocean Physics Projects
A vast renewal event happens each spring as a wave of tiny plant growth covers the North Atlantic Ocean. This mass greening of the ocean’s surface is observed dramatically from space by color-sensitive sensors on satellites as it extends from Bermuda to the ice edge in the Arctic during the season. The phytoplankton of the North Atlantic bloom play a major role in pulling CO2 from the atmosphere and storing it in the ocean. Despite the magnitude and importance of this event, it has rarely been observed from start to end due to the difficulty and expense of maintaining ships in the region for many months.
APL-UW investigators, their students, and colleagues from the University of Maine and Dalhousie University in Nova Scotia led an ambitious collaborative experiment in the North Atlantic near Iceland to coincide with the bloom in 2008. The challenge of the experiment was to characterized the bloom’s temporal and spatial evolutions of physics, biology, and chemistry over its entire duration.