Synergistic Use of Satellite and In-Situ Current Data to Improve the Characterisation of Seasonal Trends

The synergistic use of measured in-situ current data and altimetry derived geostrophic current data provides improved seasonal characterisation of the current regime, West of Shetland. In September 2007, considerable downtime was experienced by an offshore operator, West of Shetland, as a result of unexpectedly high currents persisting for a number of days. This downtime was unanticipated following conclusions derived from one year of in-situ measured data, which suggested a most favourable current regime during the months August to October. Ten years of altimetry derived geostrophic currents were utilised in conjunction with approximately 3 years of in-situ data to assess the validity of the reported seasonal trend. The altimetry derived geostrophic currents correlated well with the dominating long period signal extracted from the in-situ data. Seasonal comparison between the altimetry derived geostrophic currents and the total measured signal showed the previously available measurement year had a relatively benign September. Based on the 10 years of satellite data, the inter-annual variability of the current regime West of Shetland does not show any clear seasonal trend.