Indication of low ozone anomaly in Arctic Spring during QBO-westerly and
solar-minimum years
Abstract
This study investigates the influence of the phase of quasi-biennial
oscillation (QBO) and the 11-year solar cycle on the Arctic spring
ozone, using satellite observations, reanalysis data, and outputs of a
chemistry climate model (CCM) during the period of 1979–2011. For this
duration, we found that the composite mean of the Northern Hemisphere
high-latitude total ozone in the QBO-westerly (QBO-W)/solar minimum (S)
phase indicates a large negative anomaly for the climatology in
February–March. An analysis of the passive ozone tracer defined at the
pressure levels between 220 hPa and 12 hPa in the CCM simulation
indicates that this negative anomaly is primarily caused by transport.
The negative anomaly is consistent with a weakening of the residual mean
downward motion in the polar lower stratosphere. The contribution of
chemical processes estimated using the total ozone difference between
the chemically active ozone runs and the passive tracer simulations is
less than 6% of the total anomaly in February and between 10–20% in
March. The lower ozone levels in the Arctic spring during the
QBO-W/Syears are associated with a stronger Arctic polar vortex from
late winter to early spring, which is linked to the reduced occurrence
of sudden stratospheric warming in the winter during the QBO-W/Syears.