The measurement of mesoscale vertical motions in the atmosphere

Abstract

SUMMARYA technique is described for determining the three-dimensional field of vertical air motion in the vicinity of mobile fronts. Radar reflectors are dropped from an aircraft at a height of 5 km and followed by high precision tracking radars. By making assumptions regarding the movement and conservativeness of the frontal system it has been possible to use this technique to obtain horizontal winds over a volume approximately 150 x 100 x 4 km depth with a typical drop separation of 30 km. Using the equation of continuity, vertical velocities have been calculated with an uncertainty of f 1 -2 cm s-l. In a warm front investigated on 19 January 1969, close agreement was obtained between the rainfall observed at the surface and that computed from the vertical velocities assuming saturation of the rising air.

Sir (Basil) John Mason CB. 18 August 1923 — 6 January 2015

“…The dynamics are responsible not only for providing the growth environment for cloud particles but also for imposing severe constraints on their subsequent development. Three observational investigations that Mason promoted in this area were Project Scillonia (Hardman et al 1972), the radar studies of frontal precipitation systems by the Met Office group at the Royal Radar Establishment (RRE), Malvern (13) and, as I discuss later, the GATE project in the tropical Atlantic (WMO 1972): these all led to a better understanding of precipitation systems that was subsequently incorporated into numerical weather-prediction models. The development of these models and their use for basic atmospheric research as well as for weather prediction were areas that Mason strongly supported after he left Imperial College.…”