Average Vertical Motions in the Tropical Atmosphere Observed by a Radar Wind Profiler on Pohnpei (7°N Latitude, 157°E Longitude)

Abstract

Average vertical profiles of the vertical wind obtained under clear sky conditions as weal as under conditions of both light-to-moderate and heavy rainfall am presented from data obtained using a radar wind profiler located on the island of Pohnpei (latitude 7°N, longitude 157°E). The average profiles for the precipitation conditions were obtained, insofar as possible, under conditions similar to those present within the stratiform and convective regions of tropical mesoscale convective complexes. Comparison between the vertical wind profiles obtained from the wind profiler and vertical wind profiles obtained earlier by wore conventional methods (i.e., deduced from the convergence-divergence of mesoscale horizontal winds) shows that, while the general features of the profiles obtained by both techniques are similar, the profiler results exhibit somewhat more detail. The profiler is able to resolve long-term average vertical motions down to the, ∼cm s⁻¹ subsidence that occurs under clear air conditions. Additional evidence for an apparent difference between vertical wind profiles in the Atlantic and Pacific regions in heavy convection reported earlier, is presented.