Abstract's details
Synergetic use of surface drifters and altimetry to increase resolution and accuracy of maps of sea level anomaly in the Gulf of Mexico
CoAuthors
Event: 2017 Ocean Surface Topography Science Team Meeting
Session: Science III: Mesoscale and sub-mesoscale oceanography
Presentation type: Type Poster
Contribution: PDF file
Abstract:
Strong improvements have been made in our knowledge of the surface ocean geostrophic circulation thanks to satellite observations. However, the synergy of different sources of observation (satellite and in-situ) is mandatory in order to go toward higher resolution. In this study, we combined altimetric along track Sea Level Anomalies (SLA) with velocity estimates from surface drifters to map SLA and associated geostrophic current anomalies in the Gulf of Mexico.
First, an important work is done to pre-process drifter data to extract the geostrophic component of the signal in order to be consistent with physical content of altimetry. This step include estimate and remove of Ekman current, Stokes drift and wind slippage. Two kind of drifters are used:
- Drifters from the HMI Company are processed from 2014 to 2016 (this company, part of CLS group, launches their own drifter in the Gulf of Mexico for their downstream services).
- The drifters launched in the framework of the Lagrangian Submesoscale ExpeRiment (LASER) campaign (January-April 2015) are also processed.
Second, drifters and along track SLA from Jason2, HY2 and Saral are combined through multivariate objective analysis to map a time series of SLA and associated geostrophic current anomalies. Finally, comparisons with independent data (along track SLA from Cryosat2 and drifters) show the better agreement of maps merging both altimetry and drifters than maps using altimetry only.
First, an important work is done to pre-process drifter data to extract the geostrophic component of the signal in order to be consistent with physical content of altimetry. This step include estimate and remove of Ekman current, Stokes drift and wind slippage. Two kind of drifters are used:
- Drifters from the HMI Company are processed from 2014 to 2016 (this company, part of CLS group, launches their own drifter in the Gulf of Mexico for their downstream services).
- The drifters launched in the framework of the Lagrangian Submesoscale ExpeRiment (LASER) campaign (January-April 2015) are also processed.
Second, drifters and along track SLA from Jason2, HY2 and Saral are combined through multivariate objective analysis to map a time series of SLA and associated geostrophic current anomalies. Finally, comparisons with independent data (along track SLA from Cryosat2 and drifters) show the better agreement of maps merging both altimetry and drifters than maps using altimetry only.