S. Crewell et al., MILLIMETER-WAVE SPECTROSCOPIC MEASUREMENTS OVER THE SOUTH-POLE .1. A STUDY OF STRATOSPHERIC DYNAMICS USING N2O OBSERVATIONS, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 100(D10), 1995, pp. 20839-20844
Millimeter wave measurements of N2O and O-3 [Cheng ef al., 1995], alon
g with several other trace gases, have been made nearly continuously f
rom February 1993 through early January 1994 at the Amundsen-Scott Sta
tion, South Pole. In order to separate chemical and dynamical effects,
this paper uses the observations of the long-lived tracer N2O to stud
y stratospheric dynamics. The main emphasis is on the synoptic evoluti
on of the polar vortex over an entire winter period, and quantitative
results are given for various times and altitudes. Diabatic descent ra
tes derived for different altitude levels showed the strongest descent
in austral fall at high altitudes, agreeing fairly well with model pr
edictions by Rosenfield et al. (1994). Subsidence was observed to cont
inue until late October, well after polar sunrise. The breakdown of th
e vortex occurred first in the upper stratosphere, marked in the intru
sion of N2O rich air at these altitudes, consistent with trajectory ca
lculations. Our calculated descent rates are not consistent with the i
dea that the polar vortex is a ''flowing processor'', but instead shou
ld be viewed as an isolated system.