Airflow distortion at anemometer sites on the OWS Polarfront

Accurate wind speed measurements from anemometers on research ships are required to obtain high quality air-sea flux measurements. However, the measurements can be biased by the distortion of the airflow over the ship, i.e. the wind speed can either be accelerated or decelerated by the presence of the ship and the flow of air can be displaced vertically over the ship's superstructure. The computational fluid dynamics software VECTIS was used to numerically simulate the airflow over the Ocean Weather Ship Polarfront. The airflow distortion at six anemometer sites has been quantified for a wind speed of 10 ms-1 blowing a) directly over the bows of the ship and b) over the ship’s starboard beam. The wind speed errors ranged fromdecelerations of about 1 % for an airflow directly over the bow to accelerations of 10 % for the beam-on flow.