Supporting information Text S2.
The first step is to retrack the raw SGDR waveforms from Jason-1 and Jason-2 altimeter missions using a two-pass waveform retracker (Sandwell et al. 2014). The second step is to low-pass filter and resample the 20-Hz retracked height into ~5 Hz, to enhance the signal to noise. The third step is to correct the retracked height using state of the art geophysical and range corrections (Andersen and Scharroo, 2011). The fourth step is to perform outlier editing through comparing height and along-track slopes with the associated heights and along track slopes from EGM2008 as described by Zhang et al., (2020). The fifth step is to remove the slopes of the EGM2008 geoid and the slopes of the Mean Dynamic Topography (DOT_min1x1_EGM08) associated with the EGM2008 geoid) and to apply a low-pass filter in order to obtain along-track filtered sea surface height gradients.
Finally, the along-track sea surface slopes were turned into residual vertical deflections and then residual gravity anomalies. Subsequently the marine gravity anomalies at 1’×1’ resolution were then computed by restoring the EGM2008 gravity field associated with the EGM2008 geoid model (Zhang et al., 2017).

References

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