Optimal Interpolation details

• cov = s^2 exp(-ar)(1 + ar + 1/6 (ar)^2 - 1/6 (ar)^3) exp(-t/T)^2
• along-track OI of T/P and ERS data with a = 1/50km, error variance 4E-4m^2
• coastal tide gauges (triangles) filtered at 5 days
• 'bogus gauges' (circled) interpolated along coast
• outer shelf height estimates = coast - local and remote wind forcing
• OI with T=15days, a = 1/130km, error variance 5E-5m^2
• add 2nd OI of residuals with a = 1/50km, error variance 6.4E-5m^2
• overlapping data windows of 25 days