Oscillations in Mesocyclone Signatures with Range Owing to Azimuthal Radar Sampling

Abstract

When a thunderstorm mesocyclone changes range relative to a Doppler radar, the deduced core diameter and mean rotational velocity of the Doppler velocity mesocyclone signature oscillate back and forth, even though the radar beam?s physical width changes uniformly with range. The authors investigated the oscillations using a model mesocyclone and a simulated Doppler radar that collected data with an azimuthal sampling interval of 1°. They found that the oscillations are a consequence of changing data point separation with range relative to the Doppler velocity peaks of the mesocyclone signature.