Along-track resolution and uncertainty of altimeter-derived wave height and sea level: re-defining the significant wave height in extreme storms

Retracking of altimeter waveforms yields fluctuations in wave height and sea level, correlated at the scale of the effective footprint• A good approximation for the effective footprint diameter is the square root of the product of wave height and satellite altitude• An estimation of phenomenal wave heights precise to better than 2% requires filtering over wave groups, typically over a distance of 20 to 50 km