Drivers of the Recent Tropical Expansion in the Southern Hemisphere: Changing SSTs or Ozone Depletion?

Abstract Observational evidence indicates that the southern edge of the Hadley cell (HC) has shifted southward during austral summer in recent decades. However, there is no consensus on the cause of this shift, with several studies reaching opposite conclusions as to the relative role of changes in sea surface temperatures (SSTs) and stratospheric ozone depletion in causing this shift. Here, the authors perform a meta-analysis of the extant literature on this subject and quantitatively compare the results of all published studies that have used single-forcing model integrations to isolate the role of different factors on the HC expansion during austral summer. It is shown that the weight of the evidence clearly points to stratospheric ozone depletion as the dominant driver of the tropical summertime expansion over the period in which an ozone hole was formed (1979 to late 1990s), although SST trends have contributed to trends since then. Studies that have claimed SSTs as the major driver of tropical expansion since 1979 have used prescribed ozone fields that underrepresent the observed Antarctic ozone depletion.

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Northern Hemisphere Stratospheric Ozone Depletion Caused by Solar Proton Events: The Role of the Polar Vortex

Geophysical Research Letters ◽

10.1002/2017gl075966 ◽

2018 ◽

Vol 45 (4) ◽

pp. 2115-2124 ◽

Cited By ~ 5

Author(s):

M. H. Denton ◽

R. Kivi ◽

T. Ulich ◽

M. A. Clilverd ◽

C. J. Rodger ◽

...

Keyword(s):

Northern Hemisphere ◽

Ozone Depletion ◽

Stratospheric Ozone ◽

Polar Vortex ◽

Solar Proton ◽

Stratospheric Ozone Depletion ◽

Solar Proton Events

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Sensitivity of the Amundsen Sea Low to Stratospheric Ozone Depletion

Journal of Climate ◽

10.1175/jcli-d-13-00657.1 ◽

2014 ◽

Vol 27 (24) ◽

pp. 9383-9400 ◽

Cited By ~ 16

Author(s):

Ryan L. Fogt ◽

Elizabeth A. Zbacnik

Keyword(s):

Ozone Depletion ◽

Climate Models ◽

Stratospheric Ozone ◽

Austral Summer ◽

Lower Troposphere ◽

Southern Annular Mode ◽

Stratospheric Ozone Depletion ◽

Austral Spring ◽

Regional Warming ◽

Amundsen Sea

Abstract Dramatic sea ice loss in the Amundsen and Bellingshausen Seas and regional warming in West Antarctica and the Antarctica Peninsula have been observed over the last few decades. Both of these changes are strongly influenced by the presence of the Amundsen Sea low (ASL), a climatological region of low pressure in the Amundsen Sea. Studies have demonstrated a deepening of the ASL, particularly in austral spring and to a lesser extent autumn, the former related to decreases in the underlying cyclone central pressures and the latter previously suggested to be due to stratospheric ozone depletion. This study further investigates the sensitivity of the ASL to stratospheric ozone depletion using geopotential height from a suite of chemistry–climate models (CCMs) as well as historical simulations from phase 5 of the Coupled Model Intercomparison Project (CMIP5). Overall, both model types capture the mean characteristics of the ASL, although they have notable positive height biases at 850 hPa and a subdued seasonal cycle in its longitudinal position. Comparing across model simulations, it is observed that there is a pronounced influence of stratospheric ozone depletion in the vicinity of the ASL in the stratosphere through the lower troposphere during austral summer, consistent with the positive phase of the southern annular mode. In the autumn, the authors note a weaker, secondary influence of stratospheric ozone depletion on the ASL only in the CMIP5 simulations.

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A meta-analysis of plant field studies simulating stratospheric ozone depletion

Oecologia ◽

10.1007/s004420000592 ◽

2001 ◽

Vol 127 (1) ◽

pp. 1-10 ◽

Cited By ~ 317

Author(s):

Peter S. Searles ◽

Stephan D. Flint ◽

Martyn M. Caldwell

Keyword(s):

Ozone Depletion ◽

Meta Analysis ◽

Stratospheric Ozone ◽

Field Studies ◽

Stratospheric Ozone Depletion

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Stratospheric Ozone Depletion: The Main Driver of Twentieth-Century Atmospheric Circulation Changes in the Southern Hemisphere

Journal of Climate ◽

10.1175/2010jcli3772.1 ◽

2011 ◽

Vol 24 (3) ◽

pp. 795-812 ◽

Cited By ~ 360

Author(s):

Lorenzo M. Polvani ◽

Darryn W. Waugh ◽

Gustavo J. P. Correa ◽

Seok-Woo Son

Keyword(s):

Twentieth Century ◽

Greenhouse Gases ◽

Atmospheric Circulation ◽

Southern Hemisphere ◽

Ozone Depletion ◽

General Circulation ◽

Stratospheric Ozone ◽

Hadley Cell ◽

Stratospheric Ozone Depletion ◽

Circulation Changes

Abstract The importance of stratospheric ozone depletion on the atmospheric circulation of the troposphere is studied with an atmospheric general circulation model, the Community Atmospheric Model, version 3 (CAM3), for the second half of the twentieth century. In particular, the relative importance of ozone depletion is contrasted with that of increased greenhouse gases and accompanying sea surface temperature changes. By specifying ozone and greenhouse gas forcings independently, and performing long, time-slice integrations, it is shown that the impacts of ozone depletion are roughly 2–3 times larger than those associated with increased greenhouse gases, for the Southern Hemisphere tropospheric summer circulation. The formation of the ozone hole is shown to affect not only the polar tropopause and the latitudinal position of the midlatitude jet; it extends to the entire hemisphere, resulting in a broadening of the Hadley cell and a poleward extension of the subtropical dry zones. The CAM3 results are compared to and found to be in excellent agreement with those of the multimodel means of the recent Coupled Model Intercomparison Project (CMIP3) and Chemistry–Climate Model Validation (CCMVal2) simulations. This study, therefore, strongly suggests that most Southern Hemisphere tropospheric circulation changes, in austral summer over the second half of the twentieth century, have been caused by polar stratospheric ozone depletion.

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