Satellite Thermal Observation of the River Shannon Plume

Thermal infra-red images from National Oceanic and Atmospheric Administration (NOAA) satellites have been used to obtain synoptic patterns of surface temperature off the west coast of Ireland. As natural tracers of surface circulation, patterns of surface temperature reveal the movement of the River Shannon plume. The plume frequents the mid-western coastal waters north of the River Shannon estuary with a length of the order of 100 km and an area of about 100 km2. The plume turns nearly 90° and travels towards the north after it leaves the river mouth. When approaching the Aran Islands, the plume usually turns to the northwest. Sometimes it divides into two parts, one going northeast towards Galway Bay and the other going northwest and meeting the open sea. The effect of the river discharge rate, of wind and of tide on the plume dynamics have been studied. The amount of the river discharge affects the area of the plume but does not change the direction of the plume movement. On the other hand, the winds are effective in dispersing and extending the plume. The tidal effect on the plume appears very weak