Seasonal Hydrography of Ameralik: A Southwest Greenland Fjord Impacted by a Land-Terminating Glacier

Greenland's coastal zone encompasses a large number of fjords, many of which are impacted by glacial meltwater runoff from land-terminating glaciers. This type of fjord has received limited research attention, yet may represent the future of other fjords currently impacted by marine-terminating glaciers that are retreating. In this study we describe the seasonal hydrography of Ameralik, a fjord on the southwest coast of Greenland impacted by a land-terminating glacier. To complement this analysis we compare our results with observations from the neighbouring Godthabsfjord, which receives meltwater from both land- and marine-terminating glaciers. We find that the absence of subglacial discharge and glacial ice in Ameralik has a strong impact on the inner fjord density profiles and on circulation. The mean temperature of the upper 50 m layer was lower in Ameralik than Godthabsfjord in May, but by September was 2 degrees C higher in Ameralik. Dense coastal inflows occur in the late winter months in Ameralik, flushing the fjord and contributing to the return to a weakly stratified state. During the runoff period the surface waters are subject to estuarine circulation and wind forcing, while at intermediate depths a density gradient between the inner and outer fjord regions produces an intermediate baroclinic circulation, resulting in the exchange of water in this layer and the deepening of isopycnals. During summer a large fraction of the meltwater runoff is retained within the fjord rather than being exported. A substantial export of this summer accumulated freshwater occurs in connection with coastal inflows during winter.