Products from tide gauge data
Sea level trends around the UK coastline
Sea level trends for locations around the UK coastline are plotted as in monthly and yearly mean form
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For more information use the
UK Mean Sea Level (MSL) time series - international locations are also included in this database.
British Isles sea level index - extended from Woodworth, P.L., Tsimplis, M.N., Flather, R.A. and Shennan, I. 1999.
A review of the trends observed in British Isles mean sea level data measured by tide gauges. Geophysical Journal International, 136, 651-670.
This shows averaged interannual variability (long term trends removed) from the five long station records.
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Long records of annual MSL data from Aberdeen, North Shields, Sheerness, Newlyn and Liverpool were used to provide a representative sampling of sea level change around the coastline. First, the long term rate of MSL change was removed from each record, thereby removing contributions from vertical land movements and (linear) climate change associated sea level rise. Then, MSL values from the 5 records were averaged to make an index of UK interannual and decadal MSL variability, with the index having zero trend by construction, as shown in (a). (The standard deviation of the 5 values about their mean in any one year is typically 25 mm except for the early years of the 20th century when it is several times larger.)
Finally, a UK-average value for the long term climate change component of MSL change, estimated from a comparison of tide gauge and geological rates at a number of UK sites, was added to make the time series in (b). This average long term trend is estimated as 1.4 +/- 0.2 mm/year which is slightly lower than the 1.7 mm/year consensus value for global sea level change over a similar period.
Longer British Isles records
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Changes in extreme high and low sea levels
Newlyn and Aberdeen are at opposite ends of the UK and have some
of the longer data sets of hourly (or 15 minute) sea level data.
The smaller red and blue dots in the plot below for Newlyn show
the time series of annual 99 and 1 percentile levels respectively
(i.e. the levels which sea level is exceeded 1 and 99 percent
of the time) with the long term average for each series set to zero.
The use of 99 and 1 percentiles is sometimes preferred over the
choice of the annual maximum and minimum water levels (i.e. 100
and 0 percentiles respectively) as they provide a description
of change in high and low water characteristics without the
greater variability inherent in the true extremes.
The larger red and blue dots show the annual maximum and
minimum water levels relative to the long term means for the
99 and 1 percentiles.
The long term trend in 99 and 1 percentile is 2.2 and 1.8 mm/year,
compared to the trend of 2.1 mm/year in median sea level. Trends
for the extremes are more difficult to calculate because of the
greater variability in their records. Those for high and low
extreme levels are 2.2 and 1.3 mm/year. The small gradual greater
increase in high waters over low waters is considered to be a
consequence of increasing local tidal amplitudes (see e.g.
Araujo, I.B. and Pugh, D.T. 2007.
Sea levels at Newlyn 1915-2005: analysis of trends for
future flooding risks. Journal of Coastal Research, in press).
The corresponding plot for Aberdeen shows trends of 1.9 and
1.3 mm/year for the 99 and 1 percentiles for the period shown,
compared to 1.3 mm/year for the median percentile. High and low
extremes are again noisier and indicate trends of 3.8 and 0.0 mm/year.
PDF version of this plot (56K)
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Acrobat Reader v4 or above)
PDF version of this plot (56K)
(pdf files require
Acrobat Reader v4 or above)