Is the Brewer-Dobson circulation increasing or moving upward?

Sophie Oberländer-Hayn, Edwin P. Gerber, Janna Abalichin, Hideharu Akiyoshi, Andreas Kerschbaumer, Anne Kubin, Markus Kunze, Ulrike Langematz, Stefanie Meul, Martine Michou, Olaf Morgenstern, Luke D. Oman

Research output: Contribution to journalArticlepeer-review

Abstract

The meridional circulation of the stratosphere, or Brewer-Dobson circulation (BDC), is projected to accelerate with increasing greenhouse gas (GHG) concentrations. The acceleration is typically quantified by changes in the tropical upward mass flux (Ftrop) across a given pressure surface. Simultaneously, models project a lifting of the entire atmospheric circulation in response to GHGs; notably, the tropopause rises about a kilometer over this century. In this study, it is shown that most of the BDC trend is associated with the rise in the circulation. Using a chemistry-climate model (CCM), Ftrop trends across 100 hPa are contrasted with those across the tropopause: while Ftrop at 100 hPa increases 1-2 %/decade, the mass flux entering the atmosphere above the tropopause actually decreases. Similar results are found for other CCMs, suggesting that changes in the BDC may better be described as an upward shift of the circulation, as opposed to an increase, with implications for the mechanism and stratosphere-troposphere exchange.

Original languageEnglish (US)
Pages (from-to)1772-1779
Number of pages8
JournalGeophysical Research Letters
Volume43
Issue number4
DOIs
StatePublished - Feb 28 2016

Keywords

  • Brewer-Dobson circulation
  • climate change
  • stratosphere
  • tropical upward mass flux
  • tropopause
  • upward shift

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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