Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/acp-2017-823
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
12 Sep 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Atmospheric Chemistry and Physics (ACP).
Energy transport, polar amplification, and ITCZ shifts in the GeoMIP G1 ensemble
Rick D. Russotto1 and Thomas P. Ackerman1,2 1Department of Atmospheric Sciences, University of Washington, Seattle, Washington, USA
2Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, Seattle, Washington, USA
Abstract. The polar amplification of warming and the ability of the inter-tropical convergence zone (ITCZ) to shift to the north or south are two very important problems in climate science. Examining these behaviors in global climate models (GCMs) running solar geoengineering experiments is helpful not only for predicting the effects of solar geoengineering, but also for understanding how these processes work under increased CO2. Both polar amplification and ITCZ shifts are closely related to the meridional transport of moist static energy (MSE) by the atmosphere. This study examines changes in MSE transport in 10 fully coupled GCMs in Experiment G1 of the Geoengineering Model Intercomparison Project, in which the solar constant is reduced to compensate for abruptly quadrupled CO2 concentrations. In G1, poleward MSE transport decreases relative to preindustrial conditions in all models, in contrast to the CMIP5 abrupt4xCO2 experiment, in which poleward MSE transport increases. Since poleward energy transport decreases rather than increasing, and local feedbacks cannot change the sign of an initial temperature change, the residual polar amplification in the G1 experiment must be due to the different spatial patterns of the simultaneously imposed solar and CO2 forcings. However, the reduction in poleward energy transport likely plays a role in limiting the polar warming in G1. An attribution study with a moist energy balance model shows that cloud feedbacks are the largest source of uncertainty regarding changes in poleward energy transport in mid-latitudes in G1, as well as for changes in cross-equatorial energy transport, which are anticorrelated with ITCZ shifts.

Citation: Russotto, R. D. and Ackerman, T. P.: Energy transport, polar amplification, and ITCZ shifts in the GeoMIP G1 ensemble, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2017-823, in review, 2017.
Rick D. Russotto and Thomas P. Ackerman
Rick D. Russotto and Thomas P. Ackerman
Rick D. Russotto and Thomas P. Ackerman

Viewed

Total article views: 276 (including HTML, PDF, and XML)

HTML PDF XML Total BibTeX EndNote
205 64 7 276 3 4

Views and downloads (calculated since 12 Sep 2017)

Cumulative views and downloads (calculated since 12 Sep 2017)

Viewed (geographical distribution)

Total article views: 276 (including HTML, PDF, and XML)

Thereof 274 with geography defined and 2 with unknown origin.

Country # Views %
  • 1

Saved

Discussed

Latest update: 18 Nov 2017
Publications Copernicus
Download
Short summary
We analyzed climate model simulations to see what happens to the way the atmosphere moves heat around when the sun is turned down in order to compensate for increased greenhouse gas concentrations. We found that the atmosphere transports less heat from the tropics to the poles, which helps us understand the patterns of warming or cooling at different latitudes. We also looked at the sources of uncertainty regarding changes in tropical rainfall patterns, and found that clouds are the biggest one.
We analyzed climate model simulations to see what happens to the way the atmosphere moves heat...
Share