Abstract's details
Seasonal estimations of baroclinic tides using MIOST model and altimeter data
CoAuthors
Event: 2023 Ocean Surface Topography Science Team Meeting
Session: Tides, internal tides and high-frequency processes (ROUND TABLE)
Presentation type: Type Poster
Contribution: PDF file
Abstract:
Thanks to its current accuracy and maturity, altimetry is considered as a fully operational observing system dedicated to various applications such as climate studies. Altimeter measurements are corrected from several geophysical parameters in order to isolate the oceanic variability and the tide correction is one of the most critical. Global ocean and loading tide models GOT and FES are used in present altimeter GDRs to remove the barotropic tide component, and the internal tides signatures can be partly corrected with specific models since recently.
Internal tides have a surface signature of several cm with wavelengths about 50-250 km for the first mode and even smaller for higher modes. In the perspective of high-resolution ocean missions, the correction of these small-scale signals is mandatory, as we need to separate all tidal variability from other oceanic signals.
Several scientific teams have developed some empirical and hydrodynamic IT models in order to correct the coherent internal tide signal for the main tidal components (M2, K1, O1 and S2; Carrere et al. 2021). Using these models allows a significant altimeter variance reduction on ocean regions where internal tides are generating and propagating, and Zaron model (2019) is now used in altimetry GDRs.
However non-stationary IT signal due to seasonal variability of the ocean conditions and the interactions with mesoscales and other ocean waves is still not corrected as it is more difficult to estimate.
Seasonal estimations of the surface IT signal have been performed using the MIOST model (Ubelmann et al. 2021), empirical estimations of seasonal IT parameters (Barbot 2022) and the entire altimeter database (1993-2020). Analysis has been conducted on two different regions (Gulf of Gascogne and Amazon off-shore area) with different oceanic behaviours. We present the regional models and their impact in terms of altimeter variance reduction on the two regions of interest.
Internal tides have a surface signature of several cm with wavelengths about 50-250 km for the first mode and even smaller for higher modes. In the perspective of high-resolution ocean missions, the correction of these small-scale signals is mandatory, as we need to separate all tidal variability from other oceanic signals.
Several scientific teams have developed some empirical and hydrodynamic IT models in order to correct the coherent internal tide signal for the main tidal components (M2, K1, O1 and S2; Carrere et al. 2021). Using these models allows a significant altimeter variance reduction on ocean regions where internal tides are generating and propagating, and Zaron model (2019) is now used in altimetry GDRs.
However non-stationary IT signal due to seasonal variability of the ocean conditions and the interactions with mesoscales and other ocean waves is still not corrected as it is more difficult to estimate.
Seasonal estimations of the surface IT signal have been performed using the MIOST model (Ubelmann et al. 2021), empirical estimations of seasonal IT parameters (Barbot 2022) and the entire altimeter database (1993-2020). Analysis has been conducted on two different regions (Gulf of Gascogne and Amazon off-shore area) with different oceanic behaviours. We present the regional models and their impact in terms of altimeter variance reduction on the two regions of interest.