Project Rationale
High-resolution satellite images of ocean colour reveal a multitude of oceanic features at scales below 10km. Small eddies, whirls and filaments permeate the global ocean but are particularly frequent near current jets, mesoscale eddies, in coastal seas and near sea ice. Recent research show that these small-scale processes play a critical role in the global climate system by modulating interactions between the atmosphere, ocean, land and cryosphere - impacting vertical exchanges of heat, gases, freshwater and nutrients between the surface and the ocean interior [1] and horizontal transport pathways [2]. However, today’s knowledge of these processes stems mainly from models, with little observational data available for validation. Measuring small scales in situ is extremely challenging, expensive and rare. This project investigates a new type of ocean observations from the innovative OSCAR airborne system that images ocean current and wind fields at 1km resolution or finer. The project analyses data from two recent airborne campaigns in France and the Netherlands, comparing with high-resolution models, in situ sensors and satellites. The project will demonstrate the added-value of OSCAR data to understand and model small-scale ocean dynamics, and strengthen the scientific motivation of the Earth Explorer 11 SEASTAR mission candidate [3].
Methodology
SEASTAR is one of four candidate missions currently studied for the prestigious Earth Explorer 11 programme of the European Space Agency (ESA). SEASTAR uses Synthetic Aperture Radar along-track interferometry to measure 2D fields of total ocean surface currents and winds at an unprecedented 1km resolution. OSCAR is the airborne equivalent of SEASTAR, developed by ESA to confirm the observing principle and evaluate performance against independent observations. The PhD project focuses on OSCAR data acquired in May 2022 over Iroise Sea (Brittany, France) and the southern North Sea (Netherlands). The student will join the NOC team working with OSCAR to expand investigations using in situ, satellite and high-resolution models in different oceanographic and meteorological regimes. The student will have access to in situ and satellite observations acquired during the campaigns including moored ADCP, directional wave buoys, HF radar, X-band radar, stereo-photography, spaceborne SAR and optical imagers (e.g. Sentinel-1, NovaSAR-1, Sentinel-2). The student will analyse high-resolution model data from Met Office and European services to examine how well models represent ocean dynamics in different oceanographic conditions. Analyses over the continental shelf, coastal regions and near extreme tidal jets at Ouessant will highlight strengths and weaknesses to identify priorities for future airborne campaigns.
Training
The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at National Oceanography Centre. Specific training will include:
· Satellite ocean remote sensing
· Microwave radar scattering and interferometry
· Validation and analytical methods
· Data handling and programming
· Analysis of numerical model simulations
The student will join the NOC team that leads several international projects as part of European Space Agency Earth Explorer 11 SEASTAR activities. The student will be able to participate in meetings and scientific conferences, and to develop collaborations and visits with our partners in France, Netherlands, Spain, Germany and Sweden.
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