TITLE:
Effects of Sudden Stratospheric Warming Events on the Distribution of Total Column Ozone over Polar and Middle Latitude Regions
AUTHORS:
Vazhathottathil Madhu
KEYWORDS:
Stratospheric Sudden Warming, Total Column Ozone, Polar Vortex
JOURNAL NAME:
Open Journal of Marine Science,
Vol.6 No.2,
April
21,
2016
ABSTRACT: In winter the polar
stratosphere is extremely cold. During the Sudden Stratospheric Warming events,
the polar stratospheric temperature rises concurrently zonal-mean zonal flow
weakens over a short period of time. As the zonal flow weakens, the
stratospheric circulation becomes highly asymmetrical and the stratospheric
polar vortex is displaced off the pole. The polar stratospheric temperature
rises by 50°C and the stratospheric circumpolar flow reverses direction in a
span of just few days. Sudden Stratospheric Warming (SSW) leads to significant
changes in the rate of several chemical reactions which occur in the polar
stratosphere. During such events, the dynamical fields in the polar stratosphere
completely altered and columnar ozone changed. This study concentrated on the
variability of winter polar vortex, meridional temperature gradient and
associated changes in the Total Column Ozone (TCO) over the polar and middle
latitude regions. It is found that changes in the amount of column ozone are
positively correlated with polar lower stratospheric temperature with colder
(warmer) temperature correlating with less (high) amount column ozone. But in
the middle latitude region we observed negative correlations between ozone
concentration and stratospheric temperature. In almost all cases there is
sudden increase of ozone concentration over the pole and after few days the
value is reduced when the warming effect is weak. During SSW events there
observed an increase of 30 DU in TCO from the average value over the pole and
if the SSW is strong TCO is found to rise by 50 DU. But in the middle latitude
approximately 10 DU increase is noted. From the above results it may be
concluded that variability of column ozone depends on dynamic and stratospheric
chemistry over the poles and in middle latitude the variability can be
attributed to the dynamical aspects. Anomaly of column ozone is higher during
sudden stratospheric warming events over both polar and middle latitude region.
The meridional temperature gradient reverses first and after two days polar
vortex changes its direction or weakens followed by an increase of column ozone
over the polar region. An increase of 30° Kelvin in the average temperature
value noted over the polar region during sudden stratospheric warming events.