Abstract's details

Benefits of high-frequency observations for the retrieval of the wet tropospheric correction over open ocean: first results based on HRMR Sentinel-6 measurements.

Bruno Picard (Fluctus SAS, France)

Event: 2022 Ocean Surface Topography Science Team Meeting

Session: Instrument Processing: Propagation, Wind Speed and Sea State Bias

Presentation type: Type Oral

Statistical methods are usually used to provide estimations of the wet tropospheric correction (WTC), necessary to correct altimetry measurements for atmospheric path delays, using brightness temperatures measured at two or three low frequencies from a passive microwave radiometer on board the altimeter mission. Despite their overall accuracy over oceanic surfaces, uncertainties still remain in specific regions of complex atmospheric stratification.

Statistical methods are usually used to provide estimations of the wet tropospheric correction (WTC), necessary to correct altimetry measurements for atmospheric path delays, using brightness temperatures measured at two or three low frequencies from a passive microwave radiometer on board the altimeter mission. Despite their overall accuracy over oceanic surfaces, uncertainties still remain in specific regions of complex atmospheric stratification.

It has been demonstrated that high-frequency observations (above 80 GHz) would improve the performances of WTC retrieval over coastal areas and open ocean (Hermozo et al. 2018, 2019). The availability of such channels on-board Sentinel-6 HRMR (89 Hz, 130 GHz, 165 GHz) is a great opportunity to demonstrate those assertions using measurements in coincidence with the historical 3-low frequency channels. Indeed Shannon Brown shown in 2022 the very first results of a coastal algorithm that mitigates the land contamination and provides an accurate correction closer to the coast.

Within this study we will focus on the open ocean area and we will show the first results of the impact of high-frequency channels on the performance of WTC retrieval.
A 3 dense (fully-connected) layers is classically learned over ECMWF analysis and simulated brightness temperatures for each of the 6 channels.
The performances of the 6-channels WTC are compared to the operational product based on the 3-low frequency channels and discussed at global and regional scales based on the variance of SSH at cross-overs metric.
The potential of high frequency channels for the improvement of performances of WTC retrieval under precipitating conditions is also discussed over specific cases.
 

Oral presentation show times:

Room Start Date End Date
Sala Grande Tue, Nov 01 2022,14:15 Tue, Nov 01 2022,14:30
Bruno Picard
Fluctus SAS
France
bpicard@satobsfluctus.eu