Abstract's details
Atmospheric Gravity Waves signature on the sea surface: Insights from SWOT and OSCAR observations
Event: 2025 SWOT Science Team Meeting
Session: Oceanography: Calibration and Validation
Presentation type: Poster
The Surface Water and Ocean Topography (SWOT) satellite mission, launched in December 2022, delivers groundbreaking 2D and high-resolution observations of oceanic dynamics with centimeter-level precision in Sea Level Anomaly (SLA) measurements. Additionally, SWOT measures the ocean surface roughness (Normalized Radar Cross Section - NRCS), which is highly complementary to SLA to interpret processes at the interface between the ocean and the atmosphere.
During the SWOT Cal/Val 1-day repeat orbit in 2023, several campaigns were conducted under the Adopt a Crossover (AdaC) consortium. In the Western Mediterranean Sea, the BioSWOT-Med campaign focused on biogeophysical processes at the core and edge of an eddy north of Minorca. In parallel, OSCAR, the airborne demonstrator of the satellite mission concept SeaSTAR, was deployed below the western sub-swath of SWOT Track 3 during the Cal/Val period. OSCAR measures the roughness and the Doppler shift in phase of the ocean surface with a pixel of 8m and derives the ocean surface current and wind at 100m resolution. Three flights were conducted on the 5th, 7th and 8th of May 2023.
On the 8th of May, waves of about 2km wavelength are visible in SWOT SLA and NRCS. In SWOT SLA data, these waves have an amplitude of about 2 cm, corresponding to a direct inverse barometric effect of 2hPa. These waves are clearly visible in OSCAR data across the three antennas in both NRCS and phase. Météo-France AROME (resolution of ~1km) numerical model outputs confirm the existence of the wave, although the model does not reproduce the wavelength (>5km) and the amplitude (~0.2hPa). The signature visible by the SWOT and OSCAR radars on the surface roughness (NRCS) is directly due to oscillation of increased/decreased wind speed, without significant change in the wind direction.
This paper provides a comprehensive overview of the atmospheric gravity waves signature on the sea surface, highlighting the SWOT's unparalleled capability to produce 2D maps of SSH with km-scale resolution and centimeter-level precision.
During the SWOT Cal/Val 1-day repeat orbit in 2023, several campaigns were conducted under the Adopt a Crossover (AdaC) consortium. In the Western Mediterranean Sea, the BioSWOT-Med campaign focused on biogeophysical processes at the core and edge of an eddy north of Minorca. In parallel, OSCAR, the airborne demonstrator of the satellite mission concept SeaSTAR, was deployed below the western sub-swath of SWOT Track 3 during the Cal/Val period. OSCAR measures the roughness and the Doppler shift in phase of the ocean surface with a pixel of 8m and derives the ocean surface current and wind at 100m resolution. Three flights were conducted on the 5th, 7th and 8th of May 2023.
On the 8th of May, waves of about 2km wavelength are visible in SWOT SLA and NRCS. In SWOT SLA data, these waves have an amplitude of about 2 cm, corresponding to a direct inverse barometric effect of 2hPa. These waves are clearly visible in OSCAR data across the three antennas in both NRCS and phase. Météo-France AROME (resolution of ~1km) numerical model outputs confirm the existence of the wave, although the model does not reproduce the wavelength (>5km) and the amplitude (~0.2hPa). The signature visible by the SWOT and OSCAR radars on the surface roughness (NRCS) is directly due to oscillation of increased/decreased wind speed, without significant change in the wind direction.
This paper provides a comprehensive overview of the atmospheric gravity waves signature on the sea surface, highlighting the SWOT's unparalleled capability to produce 2D maps of SSH with km-scale resolution and centimeter-level precision.
Contribution: ST2025OS1-Atmospheric_Gravity_Waves_signature_on_the_sea_surface__Insights_from_SWOT_and_OSCAR_observations.pdf (pdf, 2431 ko)
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