Multimodel attribution of the Southern Hemisphere Hadley cell widening: Major role of ozone depletion

Abstract This paper investigates the connection between the delay in the final breakdown of the stratospheric polar vortex, the stratospheric final warming (SFW), and Southern Hemisphere climate trends. The authors first analyze Interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim) and three climate model outputs with different climate forcings. Climate trends appear when there is a delay in the timing of SFWs. When regressed onto the SFW dates (which reflect the anomaly when the SFW is delayed for one standard deviation of its onset dates), the anomaly pattern bears a resemblance to the observed climate trends, for all the model outputs, even without any trends. This suggests that the stratospheric and tropospheric circulations are organized by the timing of SFWs in both the interannual time scale and climate trends because of external forcings. The authors further explore the role of the SFW using a simplified dynamical model in which the ozone depletion is mimicked by a springtime polar stratospheric cooling. The responses of zonal-mean atmospheric circulation, including zonal wind, temperature, and poleward edge of the Hadley cell and the Ferrel cell, are similar to the observed climate trends. The authors divide the years into those in which the SFW is delayed and those in which it is not. The responses for the years in which the SFW is delayed are very similar to the overall response, while the stratosphere is only characterized by the localized cooling for those years in which the SFW is not delayed, with no subsequent downward influence into the troposphere. This suggests that, in order to affect the troposphere, ozone depletion must first delay the SFW so as to induce a deep response in planetary wave drag and the associated eddy-driven circulation.

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

Journal of Climate ◽

10.1175/jcli-d-15-0138.1 ◽

2015 ◽

Vol 28 (16) ◽

pp. 6581-6586 ◽

Cited By ~ 59

Author(s):

Darryn W. Waugh ◽

Chaim I. Garfinkel ◽

Lorenzo M. Polvani

Keyword(s):

Ozone Depletion ◽

Meta Analysis ◽

Stratospheric Ozone ◽

Austral Summer ◽

Hadley Cell ◽

Sea Surface ◽

Relative Role ◽

Stratospheric Ozone Depletion ◽

Antarctic Ozone

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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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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Large hemispheric differences in the Hadley cell strength variability due to ocean coupling

npj Climate and Atmospheric Science ◽

10.1038/s41612-021-00225-3 ◽

2022 ◽

Vol 5 (1) ◽

Author(s):

Rei Chemke

Keyword(s):

Southern Hemisphere ◽

Northern Hemisphere ◽

Climate Impacts ◽

Hadley Cell ◽

Hemispheric Differences ◽

Ocean Coupling ◽

Equatorial Upwelling ◽

Strength Variability ◽

Cell Strength

AbstractBy modulating the distribution of heat, precipitation and moisture, the Hadley cell holds large climate impacts at low and subtropical latitudes. Here we show that the interannual variability of the annual mean Hadley cell strength is ~ 30% less in the Northern Hemisphere than in the Southern Hemisphere. Using a hierarchy of ocean coupling experiments, we find that the smaller variability in the Northern Hemisphere stems from dynamic ocean coupling, which has opposite effects on the variability of the Hadley cell in the Southern and Northern Hemispheres; it acts to increase the variability in the Southern Hemisphere, which is inversely linked to equatorial upwelling, and reduce the variability in the Northern Hemisphere, which shows a direct relation with the subtropical wind-driven overturning circulation. The important role of ocean coupling in modulating the tropical circulation suggests that further investigation should be carried out to better understand the climate impacts of ocean-atmosphere coupling at low latitudes.

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Alpha-Effect, Current and Kinetic Helicities for Magnetically Driven Turbulence, and Solar Dynamo

International Astronomical Union Colloquium ◽

10.1017/s0252921100064885 ◽

2000 ◽

Vol 179 ◽

pp. 387-388

Author(s):

Gaetano Belvedere ◽

V. V. Pipin ◽

G. Rüdiger

Keyword(s):

Southern Hemisphere ◽

Northern Hemisphere ◽

Convection Zone ◽

Solar Surface ◽

Momentum Transport ◽

Angular Momentum Transport ◽

Magnetic Buoyancy ◽

Alpha Effect ◽

Current Helicity

Extended AbstractRecent numerical simulations lead to the result that turbulence is much more magnetically driven than believed. In particular the role ofmagnetic buoyancyappears quite important for the generation ofα-effect and angular momentum transport (Brandenburg & Schmitt 1998). We present results obtained for a turbulence field driven by a (given) Lorentz force in a non-stratified but rotating convection zone. The main result confirms the numerical findings of Brandenburg & Schmitt that in the northern hemisphere theα-effect and the kinetic helicityℋkin= 〈u′ · rotu′〉 are positive (and negative in the northern hemisphere), this being just opposite to what occurs for the current helicityℋcurr= 〈j′ ·B′〉, which is negative in the northern hemisphere (and positive in the southern hemisphere). There has been an increasing number of papers presenting observations of current helicity at the solar surface, all showing that it isnegativein the northern hemisphere and positive in the southern hemisphere (see Rüdigeret al. 2000, also for a review).

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In situ measurements constraining the role of sulphate aerosols in mid-latitude ozone depletion

Nature ◽

10.1038/363509a0 ◽

1993 ◽

Vol 363 (6429) ◽

pp. 509-514 ◽

Cited By ~ 212

Author(s):

D. W. Fahey ◽

S. R. Kawa ◽

E. L. Woodbridge ◽

P. Tin ◽

J. C. Wilson ◽

...

Keyword(s):

Ozone Depletion ◽

In Situ Measurements ◽

Sulphate Aerosols

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The role of the Mt. Merapi eruption in the 2011 Arctic ozone depletion

Atmospheric Environment ◽

10.1016/j.atmosenv.2017.07.040 ◽

2017 ◽

Vol 166 ◽

pp. 327-333 ◽

Cited By ~ 8

Author(s):

V.V. Zuev ◽

N.E. Zueva ◽

E.S. Savelieva

Keyword(s):

Ozone Depletion

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Numerical analysis of the chemical kinetic mechanisms of ozone depletion and halogen release in the polar troposphere

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-24171-2013 ◽

2013 ◽

Vol 13 (9) ◽

pp. 24171-24222 ◽

Cited By ~ 1

Author(s):

L. Cao ◽

H. Sihler ◽

U. Platt ◽

E. Gutheil

Keyword(s):

Boundary Layer ◽

Surface Area ◽

Ozone Depletion ◽

Reaction Rates ◽

The Arctic ◽

Strong Impact ◽

Reactive Surface ◽

A Value ◽

Halogen Species

Abstract. In recent years, the role of halogen species (e.g. Br, Cl) in the troposphere of polar regions is investigated after the discovery of their importance for boundary layer ozone destruction in the polar spring. Halogen species take part in an auto-catalytic chemical cycle including key self reactions. In this study, several chemical reaction schemes are investigated, and the importance of specific reactions and their rate constants is identified by a sensitivity analysis. A category of heterogeneous reactions related to HOBr activate halogen ions from sea salt aerosols, fresh sea ice or snow pack, driving the "bromine explosion". In the Arctic, a small amount of NOx may exist, which comes from nitrate contained in the snow, and this NOx may have a strong impact on ozone depletion. The heterogeneous reaction rates are parameterized by considering the aerodynamic resistance, a reactive surface ratio, β, i.e. ratio of reactive surface area to total ground surface area, and the boundary layer height, Lmix. It is found that for β = 1, the ozone depletion process starts after five days and lasts for 40 h for Lmix = 200 m. Ozone depletion duration becomes independent of the height of the boundary layer for about β≥20, and it approaches a value of two days for β=100. The role of nitrogen and chlorine containing species on the ozone depletion rate is studied. The calculation of the time integrated bromine and chlorine atom concentrations suggests a value in the order of 103 for the [Br] / [Cl] ratio, which reveals that atomic chlorine radicals have minor direct influence on the ozone depletion. The NOx concentrations are influenced by different chemical cycles over different time periods. During ozone depletion, the reaction cycle involving the BrONO2 hydrolysis is dominant. A critical value of 0.002 of the uptake coefficient of the BrONO2 hydrolysis reaction at the aerosol and saline surfaces is identified, beyond which the existence of NOx species accelerate the ozone depletion event – for lower values, deceleration occurs.

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Evaluation of the Australian Community Climate and Earth-System Simulator Chemistry-Climate Model

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-19161-2015 ◽

2015 ◽

Vol 15 (13) ◽

pp. 19161-19196

Author(s):

K. A. Stone ◽

O. Morgenstern ◽

D. J. Karoly ◽

A. R. Klekociuk ◽

W. J. R. French ◽

...

Keyword(s):

Southern Hemisphere ◽

Zonal Wind ◽

Ozone Depletion ◽

Climate Model ◽

Stratospheric Ozone ◽

Similar Amount ◽

Earth System ◽

Total Column Ozone ◽

Australian Community ◽

Community Climate

Abstract. Chemistry climate models are important tools for addressing interactions of composition and climate in the Earth System. In particular, they are used for assessing the combined roles of greenhouse gases and ozone in Southern Hemisphere climate and weather. Here we present an evaluation of the Australian Community Climate and Earth System Simulator-Chemistry Climate Model, focusing on the Southern Hemisphere and the Australian region. This model is used for the Australian contribution to the international Chemistry-Climate Model Initiative, which is soliciting hindcast, future projection and sensitivity simulations. The model simulates global total column ozone (TCO) distributions accurately, with a slight delay in the onset and recovery of springtime Antarctic ozone depletion, and consistently higher ozone values. However, October averaged Antarctic TCO from 1960 to 2010 show a similar amount of depletion compared to observations. A significant innovation is the evaluation of simulated vertical profiles of ozone and temperature with ozonesonde data from Australia, New Zealand and Antarctica from 38 to 90° S. Excess ozone concentrations (up to 26.4 % at Davis during winter) and stratospheric cold biases (up to 10.1 K at the South Pole) outside the period of perturbed springtime ozone depletion are seen during all seasons compared to ozonesondes. A disparity in the vertical location of ozone depletion is seen: centered around 100 hPa in ozonesonde data compared to above 50 hPa in the model. Analysis of vertical chlorine monoxide profiles indicates that colder Antarctic stratospheric temperatures (possibly due to reduced mid-latitude heat flux) are artificially enhancing polar stratospheric cloud formation at high altitudes. The models inability to explicitly simulated supercooled ternary solution may also explain the lack of depletion at lower altitudes. The simulated Southern Annular Mode (SAM) index compares well with ERA-Interim data. Accompanying these modulations of the SAM, 50 hPa zonal wind differences between 2001–2010 and 1979–1998 show increasing zonal wind strength southward of 60° S during December for both the model simulations and ERA-Interim data. These model diagnostics shows that the model reasonably captures the stratospheric ozone driven chemistry-climate interactions important for Australian climate and weather while highlighting areas for future model development.

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