Introduction:
Multiple single-mission sea level anomalies and tide gauge time series are combined to produce regulary gridded fields of sea surface height (SSH) anomaly in the northern part of the California Current System.
The word anomaly indicates that a multi-year temporal mean is removed from the time series at each altimeter location along the sub-satellite track.

Data used:
Corrected along track Sea Level Anomalies for the satellite single-mission data sets for Envisat, Ers-2, Topex/Poseidon, Jason-1 and GFO were downloaded from the AVISO/CLS website for the time period January 1999-September 2005. Hourly time series from coastal tide gauges for the same period of time (Jan 1999 to September 2005) were downloaded from the University of Hawaii Sea Level Center web page . Tide gauges data were low pass filtered to elimiate the effect of the tides (using a 40-hour filter) and coastal trapped waves (20-day filter). The inverse barometric correction was applied to the time series, using the Sea Level Presure from the NCEP reanalysis (www.cdc.noaa.goc).

Gridding methodology:
In order to merge comparable anomalies from the different data sets, the longest complete-year mean is removed at each alongtrack data point, for each altimeter. Gridded data are produced every seven days merging all the data in a 40 days period centered on the date considered. Before gridding, a gaussian weighting function is applied in time to those data which are at the same position in the 40-day time period considered (typically data from the 10 days cyle Topex/Poseidon and Jason satellite missions and form the tide gauges). The gridding technique is then apllied in space: data points selected by the Delaunay triangulation method are linearly interpolated.