Trends in components of sea level around the English Channel

The longest available records of hourly sea level data have been analysed for six ports around the English Channel. The quality of the data is extremely variable with the longest and most reliable records belonging to Brest and Newlyn. A separate analysis of the components of sea level: mean sea level, tides and meteorological residuals (surges), is used. Results show a general increase in mean sea level throughout the period of observation. The various tidal constituents show interesting local short-term variations in amplitude and phase but no longterm trends. There is no evidence of an increase in weather effects on sea levels over the period analysed. De-trended sea level and pressure values show annual sea level fall as annual air pressures increase, as expected for the inverse barometer response. Meteorological residuals were compared to North Atlantic Oscillation (NAO) index values. The correlations are in general very small, especially for the annual mean NAO values. However correlations are slightly more apparent for the annual winter mean NAO values.