Tidal and non-tidal sea level variability along the coastal Nova Scotia from satellite altimetry

Abstract

TOPEX/Poseidon (T/P) sea level data are used to investigate tidal and non-tidal sea level variability over the Scotian Shelf. Eight major diurnal and semi-diurnal tidal constituents are derived from the September 1992 to December 2001 T/P data. The present altimetric tides agree generally with in situ observations and show an error reduction of over 30° in phase over Han et al.’s [Han, G., Ikeda, M. and Smith, P.C., 1996, Oceanic tides on the Newfoundland and Scotian Shelves from TOPEX/POSEIDON altimetry. Atmosphere–Ocean, 34, pp. 589–604] results for the diurnal tides. De-tided T/P sea level data are used to provide geo-referenced seasonal-mean sea surface topography during the period September 1992 to July 2002. The T/P data are explored to estimate seasonal-mean sea level along the Nova Scotia coast. Comparisons with sea level measurements from coastal tide gauges are carried out to evaluate the potential of altimetry data for coastal sea level monitoring. Seasonally the sea level is highest along the coast in late autumn/early winter (associated with the peak of the Nova Scotian Current), and over the Scotian Slope in summer. On the interannual scale it was low in the early 1990s, high in the mid 1990s, and close to normal in the late 1990s and early 2000s.