Influence of Estuarine Tidal Mixing on Structure and Spatial Scales of Large River Plumes

The Yenisei and Khatanga rivers are among the largest estuarine rivers that inflow to the Arctic Ocean. Discharge of the Yenisei River is one order of magnitude larger than of the Khatanga River. However, spatial scales of buoyant plumes formed by freshwater runoffs from the Yenisei and Khatanga gulfs are similar. This feature is caused by different tidal forcing in these estuaries, which have similar sizes, climate conditions, and geomorphology. The Khatanga discharge exhibits strong tidal forcing that causes formation of a diluted bottom-advected plume in the Khatanga Gulf. This deep and low stratified plume has low freshwater fraction and, therefore, occupies large area at the sea shelf. The Yenisei Gulf, on the opposite, is a salt-wedge estuary that receives large freshwater discharge and is limitedly affected by tidal mixing. As a result, low-saline and strongly stratified Yenisei plume has high freshwater fraction and its horizontal size is relatively small.