Developments on current observations from HF radars
Lead: CNR-ISMAR (Annalisa Griffa)
The task will build upon the present state of the art regarding instrument retrievals of surface current velocity and integration with information from other coastal data. The general goals are to improve the quality of current estimates and to integrate the surface information from HF radar with vertical information from the other components of the coastal observing system to improve 4D transport estimates.
The task is based on the joint effort of the participating partners and addresses the following 3 specific ways forward:
- New HF radar procedures for current retrievals and data quality
- HF radar network developments
- New products for 4D characterization of shelf/slope hydrodynamics and transport.
SubTask: 3.2.1 New HF radar procedures for current retrievals and data quality control (led by HZG): The development will concentrate on the influence of strong variability of currents and bathymetry in space and time that are still problematic for state of the art HF radar current and sea state retrievals. The partners will consider both direction-finding and phased-array HF radar systems and they will specifically address the influence of a) shallow water environments (<10 m), b) areas close to river outflow, and c) high sea state conditions. A crucial point is also error quantification and quality control. Ways forward beyond the present state of the art will be investigated, including the use of a Machine Learning approach, and filtering processes and error map quantification will be improved. Joint validation surveys and common protocols for cross-validation (drifters, fixed platforms) for these new procedures will be performed in different representative study areas.
SubTask: 3.2.2 HF radar network developments (led by AZTI): Developments include improvements on HF radar network design. Based on the analysis of existing systems and future developments scenarios (new antenna locations, data processing, baseline gaps methods), guidelines will be produced for optimizing and developing HF radar systems at regional scales. For this assessment, different combinations of technological hardware solutions will be analysed (including different method of angle determination, direction finding versus beam forming). Moreover, existing data assimilation methodologies (OSSEs extended in 3.7) will be used to compare different scenarios.
SubTask: 3.2.3 New products for 4D characterization of shelf/slope hydrodynamics and transport (led by CNR-ISMAR): New developments will be performed for an integrated shelf/slope hydrodynamics characterization and for transport assessment. The 3D structure of the current will be investigated integrating surface HF radar currents with information from data within the water column, i.e. data from ADCPs, buoys, drifters, gliders as well as numerical models. Also the relationship between HF radar surface currents, water column structure, and atmospheric variables will be considered to increase process understanding. Improvements of Lagrangian products for tracking biological and pollution quantities using HF radar data will be developed. Methods to compute error maps for trajectories from HF radar currents will be investigated and quantitatively tested. Short-term prediction tools will be improved based on HF radar and other integrated data.
Deliverable 3.3: Report on first methodological improvements on current retrieval algorithms and HF radar network design. Results obtained up to date in SubTasks 3.2.1 and 3.2.2, providing first recommendations on the implementation of improved techniques for HF radar systems (M24)
Deliverable 3.4: Report on final assessment of methodological improvements and testing on the JERICO infrastructures. (M46).