Global atmospheric teleconnections and multidecadal climate oscillations driven by Southern Ocean convection
Autor: | Anand Gnanadesikan, Irina Marinov, Anna Cabré |
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Rok vydání: | 2017 |
Předmět: |
Convection
Atmospheric Science Atmosphere-ocean interaction 010504 meteorology & atmospheric sciences Atmospheric circulation Baroclinity General circulation models Westerlies 010502 geochemistry & geophysics Atmospheric sciences 01 natural sciences Energy transport Climatology Middle latitudes Environmental science Climate model Hadley cell Radiation budgets Climate variability Deep convection 0105 earth and related environmental sciences Teleconnection |
Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
ISSN: | 1520-0442 0894-8755 |
Popis: | A 1000-yr control simulation in a low-resolution coupled atmosphere-ocean model from the Geophysical Fluid Dynamics Laboratory (GFDL) family of climate models shows a natural, highly regular multidecadal oscillation between periods of Southern Ocean (SO) open-ocean convection and nonconvective periods. It is shown here that convective periods are associated with warming of the SO sea surface temperatures (SSTs), and more broadly of the Southern Hemisphere (SH) SSTs and atmospheric temperatures. This SO warming results in a decrease in the meridional gradient of SSTs in the SH, changing the large-scale pressure patterns, reducing the midlatitude baroclinicity and thus the magnitude of the southern Ferrel and Hadley cells, and weakening the SO westerly winds and the SH tropical trade winds. The rearrangement of the atmospheric circulation is consistent with the global energy balance. During convective decades, the increase in incoming top-of-the-atmosphere radiation in the SH is balanced by an increase in the Northern Hemisphere (NH) outgoing radiation. The energy supplying this increase is carried by enhanced atmospheric transport across the equator, as the intertropical convergence zone and associated wind patterns shift southward, toward the anomalously warmer SH. While the critical role of the SO for climate on long, paleoclimate time scales is now beyond debate, the strength and global scale of the teleconnections observed here also suggest an important role for the SO in global climate dynamics on the shorter interannual and multidecadal time scales. |
Databáze: | OpenAIRE |
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