The validation of geophysical parameters relies on comparisons with reference data that can be split in three main categories:
Model data: Global models are available everywhere with time step of 3 hours. They allow co-locations with all acquired products in Wave mode. Thus, they can be used for statistics based on large dataset. Typically one month of data with global acquisition is able to get a first estimated of the performances. However for case studies they may be insufficient as model cannot always capture the complexity of all situations. ECMWF with a 0.125° spatial resolution is used for ocean surface wind. Wave Watch 3 (WW3) with a 0.5° resolution is used for wave validation and operated at Ifremer by IOWAGA group. An ocean wave spectrum is produced for each CFOSAT Level 5x5 km boxes.
In-situ data: in-situ data are used to get reference measurements for wind, ocean wave spectra and ocean surface current. The limitation is the coverage and a good quality control.
Satellite data: They allow to check the consistency between different sensors measuring the same geophysical parameters. For ocean surface wind, radiometer, scatterometer or altimeter wind can be used. Altimeter also provides good estimate of significant wave height for wave validation and the geostrophic component of the ocean surface current for radial velcoities validation.
In addition we also investigate and monitor radar quantities such as Doppler, Normalized radar cross-section, Normalized variance of the image intensity, signal to noise ratio. They are good indicators to check if the sensor is operating nominally to produce good L2 OCN products. Indeed these radar parameters are used as input of the L2 processing.