Error estimation of Radiosonde, GPS, Satellite and Model wet tropospheric correction

Bruno Picard (CLS, France)


Marie-Laure Frery (CLS, France); Mathilde Siméon (CLS, France); Nicolas Picot (CNES, France)

Event: 2016 Ocean Surface Topography Science Team Meeting

Session: Quantifying Errors and Uncertainties in Altimetry data

Presentation type: Type Poster

The wet tropospheric correction (WTC) is a major source of uncertainty in altimetry budget error, due to its large spatial and temporal variability: this is the reason why the main altimetry missions include a microwave radiometer (MR).

The commonly agreed requirement on WTC for current missions is to retrieve WTC with an error better than 1cm rms. But in the lack of any reference, it is difficult to precisely assess this error, which is often roughly estimated by the difference between the radiometer and ECMWF WTC.

Based on the work of Janssen et al. (JAOT 2007), we propose an estimation of WTC error by a triple collocation technique, the same used by Janssen to assess the error on wave height.

For this purpose, we compare different sources of WTC: radiosonde, from IGRA database, GPS, from SUOMINET network, radiometers from Jason-2 and AltiKa and ECMWF model.

Coastal areas are selected from the in-situ measurements and collocation criteria are applied. Over the 3 years of AltiKa measurements, even with drastic criteria (within 1 hour and 100 km), a large number of match-ups are available, and a limited number of locations even benefits from both radiosonde and GPS measurements.

We will discuss the errors, the correlations and calibration coefficients for the different measurements techniques and we will conclude on the impact of the WTC error on the altimetry system.

Poster show times:

RoomStart DateEnd Date
Grande Halle Thu, Nov 03 2016,11:00 Thu, Nov 03 2016,18:00
Bruno Picard