Abstract's details
Regional CalVal of Jason-2 and Envisat at three calibration sites: Corsica, Harvest and Bass Strait.
CoAuthors
Event: 2014 Ocean Surface Topography Science Team Meeting
Session: Regional and Global CAL/VAL for Assembling a Climate Data Record
Presentation type: Type Oral
Contribution: PDF file
Abstract:
In situ calibration insures regular and long-term control of the altimeter sea surface height (SSH) time series through comparisons with independent records. Usually, in situ calibration of altimeter SSH is undertaken at specific CalVal sites through the direct comparison of the altimeter data with in situ data.
For more than ten years, Noveltis has been developing a regional CalVal technique, which aims at increasing the number and the repeatability of the altimeter bias assessments by determining the altimeter bias both on overflying passes and on satellite passes located far away from the calibration site. In principle, this extends the single site approach to a wider regional scale, thus reinforcing the link between the local and the global CalVal analyses. It also provides a means to maintain a calibration time series through periods of data-outage at a specific dedicated calibration site.
The regional method was initially developed at the Corsican calibration sites of Senetosa and Ajaccio. The method was used to compute the biases of Jason-1, Jason-2 and Envisat (before and after the orbit change in 2010) at both sites, and proved its stability and generality through this cross-calibration exercise.
In 2013, the regional method was successfully implemented at the Californian site of Harvest, in close collaboration with JPL. In 2014, it was also implemented with success at the Australian site in Bass Strait, in close collaboration with the University of Tasmania.
This recent study gave the first Envisat absolute bias estimates in the Southern Hemisphere, which showed high consistency with the analyses of the global CalVal teams. These results highlight the numerous advantages of this technique for monitoring missions on any orbits such as SARAL/AltiKa, CryoSat-2, HY-2A or the future Sentinel-3, Jason-3 and Jason-CS missions.
For more than ten years, Noveltis has been developing a regional CalVal technique, which aims at increasing the number and the repeatability of the altimeter bias assessments by determining the altimeter bias both on overflying passes and on satellite passes located far away from the calibration site. In principle, this extends the single site approach to a wider regional scale, thus reinforcing the link between the local and the global CalVal analyses. It also provides a means to maintain a calibration time series through periods of data-outage at a specific dedicated calibration site.
The regional method was initially developed at the Corsican calibration sites of Senetosa and Ajaccio. The method was used to compute the biases of Jason-1, Jason-2 and Envisat (before and after the orbit change in 2010) at both sites, and proved its stability and generality through this cross-calibration exercise.
In 2013, the regional method was successfully implemented at the Californian site of Harvest, in close collaboration with JPL. In 2014, it was also implemented with success at the Australian site in Bass Strait, in close collaboration with the University of Tasmania.
This recent study gave the first Envisat absolute bias estimates in the Southern Hemisphere, which showed high consistency with the analyses of the global CalVal teams. These results highlight the numerous advantages of this technique for monitoring missions on any orbits such as SARAL/AltiKa, CryoSat-2, HY-2A or the future Sentinel-3, Jason-3 and Jason-CS missions.