Search Results

You are looking at 1 - 2 of 2 items for :

  • Author or Editor: A. C. Riddle x
  • Journal of the Atmospheric Sciences x
  • Refine by Access: All Content x
Clear All Modify Search
B. B. Balsley
and
A. C. Riddle

Abstract

Monthly-averaged horizontal and vertical mesospheric wind fields have been measured using the Poker Flat Radar at 65°N latitude during 15 months in 1980–81. The horizontal wind fields are reasonably consistent with previous observations and with some of the current theoretical models that take into account enhanced turbulence and eddy transport observed at mesospheric heights. However, the observed vertical wind field has a quasi-sinusoidal seasonal variation with peak values of 25 cm s−1 both downward near summer solstice and upward near winter solstice and is inconsistent with current models of mean circulation in the meridional plane. Because there are no other comparable vertical wind observations, the possibility of error in the vertical wind measurements was carefully considered and rejected. We conclude that the actual mean circulation is more complex than that implied by current models. Possible complicating factors include nonuniform zonal flow, multicellular meridional structure and an enhanced vertical Stokes drift that would arise from strong eddy activity.

Full access
B. B. Balsley
,
W. L. Ecklund
,
D. A. Carter
,
A. C. Riddle
, and
K. S. Gage

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.

Full access