The weakening summer circulation in the Northern Hemisphere mid-latitudes
- Rapid warming in the Arctic could influence mid-latitude circulation by reducing the poleward temperature gradient. The largest changes are generally expected in autumn or winter, but whether significant changes have occurred is debated. Here we report significant weakening of summer circulation detected in three key dynamical quantities: (i) the zonal-mean zonal wind, (ii) the eddy kinetic energy (EKE), and (iii) the amplitude of fast-moving Rossby waves. Weakening of the zonal wind is explained by a reduction in the poleward temperature gradient. Changes in Rossby waves and EKE are consistent with regression analyses of climate model projections and changes over the seasonal cycle. Monthly heat extremes are associated with low EKE, and thus the observed weakening might have contributed to more persistent heat waves in recent summers.
Author details: | Dim CoumouORCiDGND, Jascha LehmannORCiD, Johanna Beckmann |
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DOI: | https://doi.org/10.1126/science.1261768 |
ISSN: | 0036-8075 |
ISSN: | 1095-9203 |
Pubmed ID: | https://pubmed.ncbi.nlm.nih.gov/25765067 |
Title of parent work (English): | Science |
Publisher: | American Assoc. for the Advancement of Science |
Place of publishing: | Washington |
Publication type: | Article |
Language: | English |
Year of first publication: | 2015 |
Publication year: | 2015 |
Release date: | 2017/03/27 |
Volume: | 348 |
Issue: | 6232 |
Number of pages: | 4 |
First page: | 324 |
Last Page: | 327 |
Funding institution: | German Research Foundation [CO994/2-1]; German Federal Ministry of Education and Research [01LN1304A] |
Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
Peer review: | Referiert |