The Response of the Midlatitude Jet to Regional Polar Heating in a Simple Storm-Track Model

• Published in: Journal of Climate
• Main Authors: Ruggieri, Paolo, Kucharski, Fred, Novak, Lenka
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Meteorological Society 2019
• Subjects: Atmosphere; Teleconnections; Climate variability; Seasonal variability; Sea ice
• Online Access: https://doi.org/10.1175/JCLI-D-18-0257.1

Given the recent changes in the Arctic sea ice, understanding the effects of the resultant polar warming on the global climate is of great importance. However, the interaction between the Arctic and midlatitude circulation involves a complex chain of mechanisms, which leaves state-of-the-art general circulation models unable to represent this interaction unambiguously. This study uses an idealized general circulation model to provide a process-based understanding of the sensitivity of the midlatitude circulation to the location of high-latitude warming. A simplified atmosphere is simulated with a single zonally localized midlatitude storm track, which is analogous to the storm tracks in the Northern Hemisphere. It is found that even small changes in the position of the forcing relative to that storm track can lead to very different responses in the midlatitude circulation. More specifically, it is found that heating concentrated in one region may cause a substantially stronger global response compared to when the same amount of heating is distributed across all longitudes at the same latitude. Linear interference between climatological and anomalous flow is an important component of the response, but it does not explain differences between different longitudes of the forcing. Feedbacks from atmospheric transient eddies are found to be associated with this strong response. A dependence between the climatological jet latitude and the jet response to polar surface heating is found. These results can be used to design and interpret experiments with complex state-of-the-art models targeted at Arctic–midlatitude interactions. © 2019 American Meteorological Society. Manuscript received 27 April 2018, in final form 4 February 2019. The authors are thankful to three anonymous reviewers for very helpful and insightful comments. The first author is grateful to Roberto Buizza, Franco Molteni, and Panos Athanasiadis for useful discussions and remarks. The authors thank three anonymous reviewers for their helpful ...