Spatial and temporal variability of ocean temperature over the Labrador Shelf

The mid-to-bottom waters of the Labrador Shelf are shown to exhibit an anomalous along-shelf temperature gradient, with warmer waters found in the north. This feature is present in summer and autumn but appears to reverse in December: Inadequate data are available during winter and spring to draw firm conclusions regarding this feature. A time averaged heat loss of the shelf waters to the atmosphere would result on average, in colder waters in the south (because of north-south advection); however; it is shown that there is a net annual-mean input of heat to the shelf waters. An examination of the seasonal temperature cycle at standard depths reveals that its phase is almost uniform below 30-m depth on the northern banks of the Labrador Shelf The limited phase variation suggests the influence of a plume of well mixed water originating near Hudson Strait. It thus appears that mixing at the entrance to Hudson Strait imparts a phase anomaly to the seasonal cycle in the north that contributes to the observed inversion of the expected latitudinal temperature gradient.