Wet Tropospheric Correction of Wide-swath Altimeter by Optimum Interpolation Method

  Objectives  Since there is only nadir radiometer onboard for the wide-swath altimetry, the wet tropospheric delay can only be corrected by models inside the cross-swath or substituted by the nadir radio-meter measured data, which lead to the lower accuracy.

  Methods  In order to improve the accuracy of wet tropospheric correction (WTC) inside the cross-swath, an optimum interpolation method to fuse the nadir radiometer WTC is proposed, and it is verified by taken the SWOT (surface water and ocean topography) wide-swath altimeter as example.

  Results  Inside the cross-swath, when the ERA5 (ECMWF reanalysis 5th generation) data are used, the residual of WTC after correction by optimum interpolation method can be reduced by 40% compared with the nadir radiometer WTC substituted. When the simulated WTCs from the spectrum of radiometer measured WTCs are used, the residual of WTC after correction by optimum interpolation method can be reduced by 80% in all latitude areas compared with the nadir radiometer WTC substituted.

  Conclusions  The optimum interpolation method has much better accuracy than the nadir radiometer WTC substituted in the case of high water vapor variability.