Other algorithm studies
Read our other algorithm studies for current, future and multi-missions.
16 February 2023
08 June 2020
Long-term observations of trends in Sea Surface Height (SSH), as well as Total Column Water Vapour (TCWV), are critical for understanding the impacts and risks of climate change. In particular, changes in SSH are of major societal importance globally, as well as regionally. The Global Climate Observing System (GCOS) has identified both SSH and TCWV as essential climate variables (ECVs).
Atmospheric water vapour increases the refraction index of air, leading to a reduction in the speed of light as compared to dry air. The accuracy of SSH estimates from radar altimetry, therefore, depends strongly on the so-called 'wet tropospheric correction' (WTC), aimed at eliminating the temporally and spatially varying impact of the atmospheric water vapour on SSH retrievals. In fact, the spatial and temporal variability of water vapour is such that an instantaneous estimation of its impact is needed to meet the SSH accuracy requirements. Consequently, the primary role of the nadir-looking Microwave Radiometer (MWR), of the Copernicus Sentinel-3 altimetry missions, is to provide the necessary water vapour observations.
In addition to WTC, TCWV is a highly important climate variable in its own right. The atmospheric water vapour feedback is believed to be the strongest feedback mechanism in climate change, approximately doubling the direct warming impact of increased CO2 forcing [Cess et al., 1990; Forster et al., 2007].
In the frame of the AMTROC study, a novel 1DVAR-based method to derive TCWV and WTC, together with their respective uncertainties over the ice-free global ocean, initially applied to observations from the MWR instruments onboard ERS-1/2 and Envisat [Bennartz et al., 2017], has been adapted to the almost identical MWR instruments flown onboard the Sentinel-3 series of satellites.
The overall objective of this study was to contribute to enhancing the scientific quality of the Level 2 TCWV and WTC products to be derived from observations by the Microwave Radiometer (MWR) instruments onboard the Sentinel-3 series of satellites.
The AMTROC activities have been carried out in several phases:
Phase (started 12/2022:)