Change search
ReferencesLink to record
Permanent link

Direct link
Polar amplification in a coupled climate model with locked albedo
Stockholm University, Faculty of Science, Department of Meteorology .
2009 (English)In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 33, no 5, 629-643 p.Article in journal (Refereed) Published
Abstract [en]

In recent years, a substantial reduction of the sea ice in the Arctic has been observed. At the same time, the near-surface air in this region is warming at a rate almost twice as large as the global average—this phenomenon is known as the Arctic amplification. The role of the ice-albedo feedback for the Arctic amplification is still a matter of debate. Here the effect of the surface-albedo feedback (SAF) was studied using a coupled climate model CCSM3 from the National Center for Atmospheric Research. Experiments, where the SAF was suppressed by locking the surface albedo in the entire coupled model system, were conducted. The results reveal polar temperature amplification when this model, with suppressed albedo, is forced by a doubling of the atmospheric CO2 content. Comparisons with variable albedo experiments show that SAF amplifies the surface-temperature response in the Arctic area by about 33%, whereas the corresponding value for the global-mean surface temperature is about 15%. Even though SAF is an important process underlying excessive warming at high latitudes, the Arctic amplification is only 15% larger in the variable than in the locked-albedo experiments. It is found that an increase of water vapour and total cloud cover lead to a greenhouse effect, which is larger in the Arctic than at lower latitudes. This is expected to explain a part of the Arctic surface–air-temperature amplification.

Place, publisher, year, edition, pages
Springer , 2009. Vol. 33, no 5, 629-643 p.
Keyword [en]
Albedo feedback, Polar amplification, Greenhouse effect, Climate-model experiment
National Category
Earth and Related Environmental Sciences
URN: urn:nbn:se:su:diva-24815DOI: 10.1007/s00382-009-0535-6ISI: 000269188800004OAI: diva2:198362
Part of urn:nbn:se:su:diva-7473Available from: 2008-04-03 Created: 2008-04-03 Last updated: 2010-09-15Bibliographically approved
In thesis
1. On the recent Arctic Warming
Open this publication in new window or tab >>On the recent Arctic Warming
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The Arctic region attracts considerable scientific interest in these years. Some of the Earth's most pronounced signs of the recent climate change are found here. The summer sea-ice cover is shrinking at an alarming rate. At the same time the region warms faster than the rest of the globe.

The sea-ice reduction implies an increase of solar-radiation absorption at the surface leading to warming which is expected to be larger at higher than at lower latitudes. It is therefore often assumed that the sea-ice reduction is a major cause of the observed Arctic temperature amplification. However, results presented in this thesis suggest that the snow and ice-albedo feedbacks are a contributing but not dominating mechanism behind the Arctic amplification. A coupled climate-model experiment with a doubling of the atmospheric CO2 concentration reveals a considerable Arctic surface-air-temperature amplification in a world without surface-albedo feedback. The amplification is only 8 % larger when this feedback is included. Instead the greenhouse effect associated with an increase of humidity and cloud cover over the Arctic seems to play a major role for the amplification.

Reanalysis data, which are partly based on observations, show Arctic temperature amplification well above the surface in the troposphere. In the summer season, the amplification has its maximum at ~ 2 km height. These trends cannot be explained by the snow- and ice-albedo feedbacks which are expected to induce the largest amplification near the surface. Instead, a considerable part of the trends aloft can be linked to an increase of the atmospheric energy transport into the Arctic.

A major topic of this thesis is the linkage between the mid-latitude circulation and the Arctic warming. It is suggested that the atmospheric meridional energy transport is an efficient indicator of this linkage.

Place, publisher, year, edition, pages
Stockholm: Meteorologiska institutionen (MISU), 2008. 107 p.
Climate change, atmospheric energy transport
National Category
Meteorology and Atmospheric Sciences
Research subject
Atmospheric Sciences
urn:nbn:se:su:diva-7473 (URN)978-91-7155-618-9 (ISBN)
Public defence
2008-04-25, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 12 A, Stockholm, 10:00
Available from: 2008-04-03 Created: 2008-04-03Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Grand Graversen, Rune
By organisation
Department of Meteorology
In the same journal
Climate Dynamics
Earth and Related Environmental Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 77 hits
ReferencesLink to record
Permanent link

Direct link