Sensitivity study on the use of Argo data for the validation of altimeter products in the Mediterranean Sea

Antonio Sánchez-Román (IMEDEA (CSIC-UIB), Spain)

CoAuthors

Simón Ruiz (IMEDEA (CSIC-UIB), Spain); Stéphanie Guinehut (CLS (Toulouse), France); Ananda Pascual (IMEDEA (CSIC-UIB), Spain)

Event: 2015 Ocean Surface Topography Science Team Meeting

Session: Science III: Large scale and global change ocean processes: the ocean's role in climate

Presentation type: Type Poster

The existing Argo network strongly complements the observations of the ocean surface from space, especially the observation of the surface topography with satellite altimeters. The comparison of Sea Level Anomalies (SLA) provided by satellite altimeters with in-situ Dynamic Heights Anomalies (DHA) derived from the temperature and salinity profiles of Argo network contributes to better characterize the error budget associated to the altimeter observations. However, the uncertainty associated with some of these results remains relatively high and some impact studies assessing to which extent the validation of altimeter measurements by comparison with in-situ steric heights derived from the Argo network is sensitive to these in-situ data and their processing are still needed.

In this work, performed in the frame of the E-AIMS FP7 European project, we review the method of comparison between SLA and DHA in the Mediterranean Sea (regional scale) in order to validate altimeter sea level measurements with an increased confidence. Namely, we focus on the sensitivity of specific SLA gridded products provided by AVISO in the Mediterranean Sea to the reference depth (400 or 900 dbars) selected in the computation of the Argo dynamic height as an integration of the Argo T/S profiles (Coriolis-GDAC dataset) through the water column. As a previous step to the comparison, the dynamic height anomalies were referenced to a synthetic climatology (400 or 900 m). Finally, to perform the comparison of both datasets, altimeter grids and synthetic climatologies were spatially and temporally interpolated at the position and time of each in-situ Argo profile by a mapping method based on an optimal interpolation scheme. Then, statistics and coherence analyses were carried out between altimetry and the in-situ Argo reference. The analysis was conducted in both the entire Mediterranean Sea and different sub-regions of the basin in order to (1) check biases in the altimetry validation to different reference depths of Argo DHA and (2) investigate the impacts of a given reference depth of integration on the regional and sub-regional Argo sampling and on the comparison with altimeter data. Preliminary results show that correlations between altimeter product and Argo data using 400 m as reference level are slightly higher than those obtained using a 900 m reference level. On the other hand, the standard deviation of the difference between both datasets exhibits the opposite behaviour with higher mean values in the later.

 

Poster show times:

RoomStart DateEnd Date
Grand Ballroom Foyer Thu, Oct 22 2015,11:00 Thu, Oct 22 2015,18:00
Antonio Sánchez-Román
IMEDEA (CSIC-UIB)
Spain
asanchez@imedea.uib-csic.es