The 2015 Spring Freshet and Its Effects on the Alaskan Beaufort Sea

In 2015, a unique set of measurements were collected from the landfast ice of the Alaskan Beaufort Sea, as the buoyant plume resulting from the spring freshet of the largest Arctic Alaska river, the Colville, spread beneath the sea ice covering Harrison Bay. Velocities of both the plume and the ambient shelf water beneath the plume were measured as well as salinity and temperature, particle size and concentration. A suite of geochemical measurements including dissolved oxygen, pH, total suspended solids, dissolved and particulate metals N, P, C and δ¹⁸O were made at the same time. In addition, the Colville as well as the nearby Sagavanirktok and Kuparak Rivers were sampled for many of these same parameters. This comprehensive set of measurements allows us to describe in detail the dynamics of the spring 2015 under ice freshet. The 2015 freshet on the North Slope of Alaska was marked by the rapid onset of melt simultaneously across the entire slope resulting in melt water rapidly spreading both over and under the sea ice north from the coast. Consistent with simple numerical models, the thickness of the buoyant under ice plume increased rapidly with time as well.