Two campaigns were conducted in order to prove that the main SKIM concept works, i.e., that a pulse-pair Doppler radar measurement of the ocean surface can be used to retrieve a meaningful ocean surface current. The two SKIM campaigns named DRIFT4SKIM and KUROS4SKIM address respectively the in-situ and airborne components.
The campaigns took place in November 2018 in the Iroise Sea (France). Surface currents were measured simutaneously from the sea and from the air. For the sea component (DRIFT4SKIM), 130 drifters (CARTHE, SVP) were released from two different vessels (the research vessel Thalia vessel and a smaller zodiac) into the water and follow the current which will be key to validate the airborne measurements. The airborne component (KUROS4SKIM) was composed of two aircrafts from SAFIRE. The larger aircraft, SAFIRE ATR42, was flying the main payload, a Ku-band radar developed by LATMOS called KuROS and a more experimental Ka-Band radar from IETR called KARADOC. KuROS which was developed for the French/Chinese mission CFOSAT has a rotating antenna with different beams similar to the planned SKIM payload (even though at a different frequency, since SKIM will be Ka band) and has been flying since 2012 whereas KARADOC (same frequency as SKIM but doesn’t rotate) is a recent development and underwent its first campaign with an optimized configuration for SKIM. Complementing the radar flights, there are also optical and IR instrumentation flying on a smaller SAFIRE airplane (Piper Aztec) providing a comprehensive heat signature of the ocean.
Results show that surface currents measured from the air are consistent with in-situ measurements (drifters, HF Radar). This confirms the capability of SKIM to retrieve a meaningful ocean surface current from Doppler radar measurements.