Implications of all season Arctic sea-ice anomalies on the stratosphere Deutsches Zentrum für Luft- und Raumfahrt, Institut für Physik der Atmosphäre, Oberpfaffenhofen, Germany
17 Dec 2012
Received: 13 Feb 2012 – Published in Atmos. Chem. Phys. Discuss.: 15 May 2012 Abstract. In this study the impact of a substantially reduced Arctic sea-ice cover on
the lower and middle stratosphere is investigated. For this purpose two
simulations with fixed boundary conditions (the so-called time-slice mode)
were performed with a Chemistry-Climate Model. A reference time-slice with
boundary conditions representing the year 2000 is compared to a second
sensitivity simulation in which the boundary conditions are identical apart
from the polar sea-ice cover, which is set to represent the years 2089–2099.
Revised: 28 Nov 2012 – Accepted: 04 Dec 2012 – Published: 17 Dec 2012
Three features of Arctic air temperature response have been identified which
are discussed in detail. Firstly, tropospheric mean polar temperatures
increase up to 7 K during winter. This warming is primarily driven by
changes in outgoing long-wave radiation. The tropospheric response
(e.g. geopotential height anomaly) is in reasonable agreement with similar
studies dealing with Arctic sea-ice decrease and the consequences on the
troposphere. Secondly, temperatures decrease significantly in the summer
stratosphere caused by a decline in outgoing short-wave radiation,
accompanied by a slight increase of ozone mixing ratios. Thirdly, there are
short periods of statistical significant temperature anomalies in the winter
stratosphere probably driven by modified planetary wave activity, but
generally there is no clear stratospheric response. The Arctic
Oscillation (AO)-index, which is related to the troposphere–stratosphere
coupling favours a more neutral state during winter. The only clear
stratospheric response can be shown during November. Significant changes in
Arctic temperature, meridional eddy heat fluxes and the Arctic Oscillation
(AO)-index are detected.
In this study the overall stratospheric response to the prescribed sea-ice
anomaly is small compared to the tropospheric changes.
Citation: Cai, D., Dameris, M., Garny, H., and Runde, T.: Implications of all season Arctic sea-ice anomalies on the stratosphere, Atmos. Chem. Phys., 12, 11819-11831, doi:10.5194/acp-12-11819-2012, 2012.