Abstract's details
SEA ICE RETRIEVAL FROM CRISTAL: DESIGN, DEVELOPMENT AND VALIDATION
CoAuthors
Event: 2023 Ocean Surface Topography Science Team Meeting
Session: Science IV: Altimetry for Cryosphere and Hydrology
Presentation type: Type Poster
Contribution: PDF file
Abstract:
The Copernicus Polar Ice and Snow Topography Altimeter (CRISTAL) is a satellite system developed as part of the European Union Copernicus program expansion activities. Main objective of the CRISTAL mission design is to measure and monitor variability of Arctic and Southern Ocean sea ice thickness and its snow depth. Built on the heritage of CryoSat, the CRISTAL instrument technical solution is based on a dual-frequency synthetic-aperture radar altimeter with interferometric capabilities at Ku-band and a second Ka-band frequency. Additionally CRISTAL will carry a passive microwave radiometer to support atmospheric corrections and surface-type classification. The characteristics of the CRISTAL instrument will lead to improved geophysical estimates: (i) an increased precision for sea ice freeboard and along-track resolution, exploiting the open-burst chronogram and the FFSAR processing on-ground, (ii) across-track leads detection capability by interferometric acquisitions and (iii) snow thickness retrieval by analysis of the scattering range at Ku- and Ka-band.
Throughout this abstract, the current plan for the design, development and validation of the ESA CRISTAL Level-2 products is described. The CRISTAL Level-2 products will include different geophysical parameters in the sea ice domain, in the land ice domain, in the hydrology domain and in the ocean domain. ESA is responsible for the generation of the Level-2 Thematic Data Products (TDP) related to the sea ice, land ice and hydrology aspects of the Mission.
The CRISTAL Level-2 TDP and algorithms are planned to be provisioned in a two-step approach prior to launch: a ground processor prototype will be designed and developed in a first stage, with the primary objective of defining the Level-2 product format and up-to-date algorithms for the geophysical variables retrieval to leverage the full capabilities of the CRISTAL instruments, while the operational processor will be developed in a second stage, with the objective of optimizing the computational performance and guaranteeing the integration in the Copernicus Ground Segment.
The CRISTAL Level-2 ground processor prototype in the sea ice domain will implement the geophysical retrieval algorithms for the following variables: sea ice freeboard, sea ice thickness, snow depth over sea ice, ice shelves thickness, iceberg distribution and volume. To achieve the Mission performance objectives, advanced geophysical retrieval algorithms for sea ice and icebergs are needed to be defined so that the Level-2 GPP activity will carry on R&D studies to support the definition and implementation of the retrieval algorithms. Such R&D studies will be aimed at providing answers to the current scientific open question related to the sea ice retrieval in the context of CRISTAL: (i) assess differences between sea ice freeboard derived from Ku-band and Ka-band altimetry due to the different penetration depth in snow on sea ice (ii) increasing the number of sea surface height measurements in ice-covered regions by exploitation of multi-peak retracking of waveforms, leads from adjacent tracks and swath processing, (iii) extend the geophysical retrieval capability under complex sea ice conditions (e.g. thin ice, melt ponds, summer months).
Another key task to be carried on is the definition of the methods and protocols for the validation of the CRISTAL Level-2 TDP. To this aim, Pre-Flight and In-Flight validation will be prepared. The Pre-Flight Validation will be based on the validation of the Level-2 products generated by the ground processor prototype starting from simulated altimeter radar echoes in order to preliminary assess the end-to-end performance. In-Flight validation plan will be prepared to define methods and protocols for the validation of the CRISTAL Level-2 products versus Fiducial Refence Measurements (FRM) and in synergy with other Missions, primarily with the other Copernicus Expansion Missions operating in the polar domain, namely CIMR and ROSE-L.
The activities for the design and development of the CRISTAL Level-2 ground processor prototype will start in 2023 and other ones will follow in the next years having 2027 as target date for CRISTAL launch.
Throughout this abstract, the current plan for the design, development and validation of the ESA CRISTAL Level-2 products is described. The CRISTAL Level-2 products will include different geophysical parameters in the sea ice domain, in the land ice domain, in the hydrology domain and in the ocean domain. ESA is responsible for the generation of the Level-2 Thematic Data Products (TDP) related to the sea ice, land ice and hydrology aspects of the Mission.
The CRISTAL Level-2 TDP and algorithms are planned to be provisioned in a two-step approach prior to launch: a ground processor prototype will be designed and developed in a first stage, with the primary objective of defining the Level-2 product format and up-to-date algorithms for the geophysical variables retrieval to leverage the full capabilities of the CRISTAL instruments, while the operational processor will be developed in a second stage, with the objective of optimizing the computational performance and guaranteeing the integration in the Copernicus Ground Segment.
The CRISTAL Level-2 ground processor prototype in the sea ice domain will implement the geophysical retrieval algorithms for the following variables: sea ice freeboard, sea ice thickness, snow depth over sea ice, ice shelves thickness, iceberg distribution and volume. To achieve the Mission performance objectives, advanced geophysical retrieval algorithms for sea ice and icebergs are needed to be defined so that the Level-2 GPP activity will carry on R&D studies to support the definition and implementation of the retrieval algorithms. Such R&D studies will be aimed at providing answers to the current scientific open question related to the sea ice retrieval in the context of CRISTAL: (i) assess differences between sea ice freeboard derived from Ku-band and Ka-band altimetry due to the different penetration depth in snow on sea ice (ii) increasing the number of sea surface height measurements in ice-covered regions by exploitation of multi-peak retracking of waveforms, leads from adjacent tracks and swath processing, (iii) extend the geophysical retrieval capability under complex sea ice conditions (e.g. thin ice, melt ponds, summer months).
Another key task to be carried on is the definition of the methods and protocols for the validation of the CRISTAL Level-2 TDP. To this aim, Pre-Flight and In-Flight validation will be prepared. The Pre-Flight Validation will be based on the validation of the Level-2 products generated by the ground processor prototype starting from simulated altimeter radar echoes in order to preliminary assess the end-to-end performance. In-Flight validation plan will be prepared to define methods and protocols for the validation of the CRISTAL Level-2 products versus Fiducial Refence Measurements (FRM) and in synergy with other Missions, primarily with the other Copernicus Expansion Missions operating in the polar domain, namely CIMR and ROSE-L.
The activities for the design and development of the CRISTAL Level-2 ground processor prototype will start in 2023 and other ones will follow in the next years having 2027 as target date for CRISTAL launch.