Annabelle Ollivier (CLS, France); Nicolas Picot (CNES, France)

The wet tropospheric correction (WTC) plays a critical role on the altimetry mission budget error due to its large spatial and temporal variability.

Ubelmann et al 2013 has shown the effect of the WTC on the performance of the future SWOT mission using simulated 2D fields obtained from spectral analysis of existing WTC measurements provided by radiometers.
This work raised some questions on the geographical and seasonal variability of WTC power density spectra (PSD), specifically on its slope, also called scaling exponent.

Based on the work of G. King and A. Stoeffelen performed on scatterometer winds (JGR 2015), we propose to analyse the sensitivity of water vapor scaling exponent using structure functions against SST, clouds and rain. Structure functions are related to PSD but preferred to these latter since less sensitive to gaps and boundary effects.

We will show how rain and convection events strongly modify the slope, we will compare AltiKa , Jason-2 and GMI water vapour products and we will conclude on how these results could affect the SWOT budget error.