Rj. Atkinson et Ra. Plumb, 3-DIMENSIONAL OZONE TRANSPORT DURING THE OZONE HOLE BREAKUP IN DECEMBER 1987, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 102(D1), 1997, pp. 1451-1466
Since the onset of springtime ozone depletion in the Antarctic lower s
tratosphere, the question has arisen as to the extent to which transpo
rt of ozone hole material out into the surrounding regions might influ
ence ozone levels at midlatitudes through a so-called ozone hole dilut
ion effect. One such event was previously identified which followed th
e vortex breakup during early December 1987, but the extent to which i
t was attributable to the presence of an Antarctic ozone deficit, rath
er than being the result of ozone transports which would have occurred
anyway in the absence of an ozone hole, was not quantified at the tim
e. Here we describe the results of a more detailed study of the Decemb
er 1987 event, in which we have addressed this issue. A quasi-conserva
tive coordinate transformation technique is used on ozone data from th
e second stratospheric aerosol and gas experiment (SAGE II) to obtain
a three-dimensional description of the hemispheric ozone distribution
immediately prior to the event. A contour advection technique is used
to describe the stratospheric material evolution during the period, an
d this provides a detailed depiction of the quasi-horizontal ozone tra
nsports which occurred at the time. The calculated dynamically induced
total ozone changes during the period are then separated into contrib
utions arising from ''vertical'' and ''horizontal'' advection. The pot
ential vorticity tendency form of the quasi-geostrophic omega equation
is solved to provide insight into the horizontal scales and vertical
domain of the dynamical ''forcing'' primarily responsible for the vert
ical advection component. Finally, by imposing a ''no ozone hole'' ozo
ne distribution during the period, and comparing the resulting ozone d
istribution with that obtained with the unmodified reconstruction, we
then isolate a significant component of the observed midlatitude total
ozone changes which was attributable solely to the presence of Antarc
tic ozone depletion.