Retrieval of mean vertical air motion in stratiform snow using Doppler Radar wind measurements

There is yet no instrument or method of calculation that gives good estimates of the vertical air motion in the mesoscale. A new attempt was made for an interesting case of stratiform snow cyclone, observed by the vertically-pointing X-band Radar (VertiX) of McGill University. Also available observations were measurements by a VHF wind profiler located 25 km from the VertiX. Both instruments measure the resultant of the dynamical air motion and the microphysics of growth of snow particles. To consider only the wind component of the Doppler velocity, first, a mean vertical air motion can be calculated from the radial wind measurements of the S-band scanning Doppler radar of McGill by integration of the horizontal divergence. Second, a synoptic vertical air motion can be computed from temperature profiles collected by commercial aircrafts.

The computed vertical air motion profiles from the aircraft measurements showed dependence with height comparable to the Doppler observations in this particular case, a phase difference between the compared profiles was also observed. Direct comparison of the vertical wind profiles computed from the radial wind measurements with observations was not conclusive, thought to be mainly due to the relatively low vertical resolution of the scanning radar and the range dependence of its results.