Impacts of River Runoff in the Arctic Ocean: Modelling Changes in Flow and Temperature

Abstract

River runoff plays a very important role in the Arctic Ocean. The Arctic Ocean accounts for around 1% of the total world ocean volume, but receives around 11% of the worlds river runoff. In addition, the Arctic Ocean is a β ocean, where stratification is primarily determined by salinity as opposed to temperature as in most of the worlds oceans. This makes many processes in the Arctic Ocean sensitive to changes in river discharge. With climate change, inflow from rivers is expected to increase into the Arctic Ocean. River water temperatures are also rising, which will increase the heat flux from rivers into the Arctic Ocean. Ocean models can provide an important tool to understand the Arctic’s response to these changes. This thesis will first introduce background information on Arctic Ocean processes, focusing on freshwater and river runoff. Ocean modelling basics will be reviewed, as well as specific information on the modelling configuration used in this work. The sensitivity of ocean model simulations to different river runoff forcing will be investigated. This will look at regional impacts particularly in the Canadian Arctic, and the propagation of runoff increases downstream into the North Atlantic. Riverine heat flux into the Arctic Ocean is also examined, by incorporating river water temperature information into ocean model simulations. Particular focus is given to the associated heat fluxes into the Arctic Ocean, as well as the impacts on sea ice.