Airflow distortion at instrument sites on the FS Polarstern

Wind speed measurements obtained from research ships are prone to systematic errors caused by the distortion of the air flow around the ship’s hull and superstructure. In this report the air flow around the FS Polarstern is simulated for a wind speed of 15 ms-1 blowing directly over the bows of the ship using Computational Fluid Dynamics (CFD). The airflow distortion at five anemometer sites has been quantified. All anemometers in this study were located on the lattice mast attached to the crane on the forecastle. The crane was extended in two positions with the anemometers 11.2m and 14.2m forward of the bows. All the anemometers experienced moderate to severe flow distortion, with the wind speed being decelerated by 6% to 15% depending on the instrument location. The flow had been displaced vertically by between 0.1m and 0.7m, with the displacement increasing with height.