360 Works

A star-tracker processor for Sentinel-6: performance and application for radar antenna pitch bias calibration

Gerard Gallardo i Peres, Ferran Gibert, Gorka Moyano, Marco Fornari, Albert Garcia-Mondéjar & Mònica Roca i Aparici
Radar altimeter processors require knowledge of platform and radar antenna attitude to provide accurate range and datation measurements. Although the attitude solution generated at real-time by the on-board computer may be accurate enough for ground applications, it is actually of interest to reprocess the star-trackers raw measurements on-ground with consolidated orbit data for validation purposes. Additionally, having more than one star-tracker on-board allows to derive independent Roll-Pitch-Yaw attitude estimates as observed from each star-tracker, what...

Blending AIS data and altimetric measurements to estimate sea surface currents in the Gulf of Mexico

Clément Le Goff, Brahim Boussidy, Solene Jousset, Sandrine Mulet & Gerald Dibarboure
The maritime traffic around the Loop current of the Gulf of Mexico is large enough to help retrieving the oceanic surface current. Using Automatic Identification System (AIS) data streams for the period 2019-2020, a distance-weighted least-squares approach [Le Goff et al 2021] is used to estimate ocean surface currents at a depth corresponding to the mean draught of the commercial vessels (about 7m). The calculated gridded data product has spatial resolution of 0.125⁰ × 0.125⁰...

Sentinel-3 SAR Mode altimetry observations of wave breaking dissipation owing to large-amplitude Internal Solitary Waves: effects on SWH and radar backscatter

Adriana M. Santos-Ferreira, José C.B. Da Silva, Jorge M. Magalhaes, Thomas Moreau, Claire Maraldi, Franck Borde & Craig Donlon
Wave breaking is a common phenomenon when there is high to medium wind speeds over the ocean. But the wave breaking can have various sources, being the wind only one of them. For instance, wave breaking occurs near inhomogeneous unsteady currents, when waves propagate into an opposing current steepen, shorten and may break; or more simply, as waves shoal over shallow bathymetry. Wave breaking limits the height of surface waves, mixes the ocean surface, generates...

Assessment of global and regional tidal models in coastal regions – a contribution to improve coastal altimetry retrievals

Mathilde Cancet, Ergane Fouchet, David Cotton & Jérôme Benveniste
Because of the repeat period of the satellite altimetry missions (from 10 days for the Topex/Jason suite to more than one year for CryoSat-2), the high-frequency ocean tidal signals are aliased in the altimeter sea surface height measurements at periods that correspond to other ocean dynamics processes. To access the ocean circulation dynamics with the centimetric accuracy expected by the users, it is thus necessary to accurately remove the ocean tide signals from the altimeter...

Improved time-variable gravity modelling using monthly COST-G models for precise orbit determination of low Earth orbiting satellites

Adrian Jäggi, Heike Peter & Ulrich Meyer
Accurate time-variable Earth’s gravity field information is essential for precise orbit determination (POD) of low Earth orbiters (LEO). In particular the POD of altimeter satellites relies on accurate modelling of the time-variable gravity field. The Combination Service for Time-variable Gravity Fields (COST-G) provides monthly gravity fields based on a combination of GRACE/GRACE-FO derived monthly gravity field solutions from different analysis centers. These monthly solutions are available with a latency of 2-3 months. They serve as...

CTOH studies for extending the range of altimetry applications over the ocean and continental surfaces

Fabien Blarel, Damien Allain, Florence Birol, Denis Blumstein, Robin Chevrier, Lucrèce DJEUMENI, Wassim Fkaier, Frederic Frappart, Yvan Gouzenes, Fabien Leger, Rosemary Morrow & Fernando Niño
The Center for Topography of the Oceans and Hydrosphere (CTOH) is a French Observation Service created in 1989 and dedicated to satellite altimetry studies. It focuses on the development and promotion of new processing approaches of the altimetric data for emerging research domains (coastal ocean, oceanic sub-mesoscale phenomenons, continental surface water, sea ice, polar caps). It works in close relationship with space agencies (mainly CNES and ESA) at different levels for satellite altimetry missions: preparation...

The new CNES-CLS 2022 marine gravity anomaly model: first validation in the Mediterranean

Philippe Schaeffer, Sean Bruinsma & Franck Reinquin
A new model of marine free-air gravity anomalies has been determined. It is based on the same data set used in the CNES CLS 2022 Mean Sea Surface determination. Particular attention was paid to the shortest wavelengths of less than 30 km. Furthermore, data sampling at 1 Hz (~7km) along track is not sufficient in this context. It is necessary to focus this new determination on the use of high-resolution data that are provided by...

Validation of altimetry by using in situ observations of pressure and acoustic travel time in the Southern Ocean

Jens Schroeter, Olaf Boebel & Roelof Rietbroek
In large parts of the Southern Ocean stratification and dynamics are relatively uniform and allow the application of the “Gravest Empirical Mode” (GEM) concept. Among other characteristics, the concept describes how variations of heat content are linearly related to those of salt content and steric height. The slope of the function depends on the local stratification. Furthermore heat content variations are a function of vertical acoustic travel time. This leads to the conclusion that measuring...

Analysis of Fully Focused and unfocused SAR data in the [0 - 5] km of the coastal strip

Ana Aldarias, Marcello Passaro, Jesús Gómez-Enri, Roberto Mulero-Martínez, Irene Laiz, Frithjof Ehlers, Florian Schlembach & Michele Scagliola
One of the most novel concepts in coastal altimetry is the Fully Focused SAR (FF SAR) processing. FF SAR introduces improvements in terms of along-track resolution in high Pulse Repetition Frequency (PRF) radar altimeters. The processing is similar to the SAR altimetry, but the along-track resolution up to the theoretical limit equal to half the antenna length (~0.5 m). This is in contrast to the ~300 m unfocused SAR along-track resolution given in coastal altimeter...

MAGAL Constellation

Arlindo Marques, Clara Lázaro, M. Joana Fernandes, Joaquim Melo, André G. C. Guerra, André João, Miguel Martin, Miguel Arantes, Paulo Figueiredo, Vitor Coelho, Nuno Borges Carvalho, Catarina M. Cecilio, Ana Martins, Yaroslav Mashtakov, Edgar Carrolo, Burke Fort & Byron Tapley
The concept of a small radar altimeter constellation has already been proposed but not yet implemented due to technological limitations or high costs associated with the operation of such a constellation. Yet, some oceanic processes are still poorly studied and understood due to the lack of adequate sampling of the ocean by past and current satellite altimetry missions. With the increase in popularity of the CubeSat concept and the current availability of low-cost and high-performance...

Registration Year

  • 2022

Resource Types

  • Conference Paper