Simulation of Recent Southern Hemisphere Climate Change

Gillett, Nathan P.; Thompson, David W. J.

doi:10.1126/science.1087440

Cited by 551 publications

(538 citation statements)

References 29 publications

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“…General circulation model (GCM) simulations forced with Antarctic ozone depletion display a positive increase in the SAM (Gillett and Thompson, 2003). Similarly, models forced by increasing (well-mixed) greenhouse gases also respond with an increase in the SAM (Cai et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

Variability and trends in the directional wave climate of the Southern Hemisphere

Hemer

Church

Hunter

2009

Intl Journal of Climatology

243

206

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The effect of interannual climate variability and change on the historic, directional wave climate of the Southern Hemisphere is presented. Owing to a lack of in situ wave observations, wave climate in the Southern Hemisphere is determined from satellite altimetry and global ocean wave models. Altimeter data span the period 1985 to present, with the exception of a 2‐year gap in 1989–1991. Interannual variability and trends in the significant wave height are determined from the satellite altimeter record (1991 to present), and the dominant modes of variability are identified using an empirical orthogonal function (EOF) analysis. Significant wave heights in the Southern Ocean are observed to show a strong positive correlation with the Southern Annular Mode (SAM), particularly during Austral autumn and winter months. Correlation between altimeter derived significant wave heights and the Southern Oscillation Index is observed in the Pacific basin, which is consistent with several previous studies. Variability and trends of the directional wave climate are determined using the ERA‐40 Waves Re‐analysis for the period 1980–2001. Significant wave height, mean wave period and mean wave direction data are used to describe the climate of the wave energy flux vector. An EOF analysis of the wave energy flux vector is carried out to determine the dominant modes of variability of the directional seasonal wave energy flux climate. The dominant mode of variability during autumn and winter months is strongly correlated to the SAM. There is an anti‐clockwise rotation of wave direction with the southward intensification of the Southern Ocean storm belt associated with the SAM. Clockwise rotation of flux vectors is observed in the Western Pacific Ocean during El‐Nino events. Directional variability of the wave energy flux in the Western Pacific Ocean has previously been shown to be of importance to sand transport along the south‐eastern Australian margin, and the New Zealand region. The directional variability of the wave energy flux of the Southern Ocean associated with the SAM is expected to be of importance to the wave‐driven currents responsible for the transport of sand along coastal margins in the Southern Hemisphere, in particular those on the Southern and Western coastal margins of the Australian continent. Copyright © 2009 Royal Meteorological Society

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Section: Discussionmentioning

confidence: 99%

Variability and trends in the directional wave climate of the Southern Hemisphere

Hemer

Church

Hunter

2009

Intl Journal of Climatology

243

206

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“…We are able, however, to investigate the effects of the long-term changes in the seasonality of the SAM, which combine to produce the observed trend [Gillett and Thompson, 2003;Thompson and Solomon, 2002]. For this, we have used the 10-year sequence of BPR data collected from 1000-m depth at the south side of Drake Passage (Figure 1).…”

Section: Resultsmentioning

confidence: 99%

“…31, L21305, doi:10.1029/2004GL021169, 2004 Copyright 2004 by the American Geophysical Union. 0094-8276/04/2004GL021169 consequences of anthropogenic influences, such as greenhouse warming or ozone depletion in the stratosphere [Kushner et al, 2001;Thompson and Solomon, 2002;Gillett and Thompson, 2003]. It is of great interest to understand what effect this has had on ocean circulation.…”

Section: Introductionmentioning

confidence: 99%

Changes in the ocean transport through Drake Passage during the 1980s and 1990s, forced by changes in the Southern Annular Mode

Meredith

Woodworth

Hughes

et al. 2004

Geophysical Research Letters

118

124

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We present the first direct evidence that interannual changes in ocean transport through Drake Passage are forced by variability in the Southern Annular Mode (SAM). This evidence is derived from two decades (1980s and 1990s) of subsurface pressure measurements from the tide gauge at Faraday station (western Antarctic Peninsula), combined with the output of an ocean general circulation model. In recent decades, the SAM has moved toward a higher‐index state (stronger circumpolar winds); this trend is not simply monotonic, but is the product of a long‐term change in the seasonality of the SAM. Whilst we cannot address directly the effect of the long‐term trend on circumpolar transport, bottom pressure data from Drake Passage during the 1990s demonstrate that ocean transport showed the same changes in seasonality as did the SAM. This offers a mechanism for atmospheric climate change to influence directly the large‐scale ocean circulation.

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“…In the southern hemisphere, these events seem robust in their decadal changes in both measurements (Thompson and Solomon, 2002) and models (Gillett and Thompson, 2003), plus in the sole example in 2002 of a sudden warming in Antarctica other than the final warming (Charlton et al, 2005). Although the cause of the mechanisms involved has yet to be established, the evidence suggests an important route whereby factors affecting the stratosphere might have an impact at the surface.…”

Section: Introductionmentioning

confidence: 94%

Influences of ozone depletion, the solar cycle and the QBO on the Southern Annular Mode

Roscoe

Haigh

2007

Quart J Royal Meteoro Soc

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ABSTRACT:We present results of multiple regressions of the leading mode of atmospheric variability at southern high latitudes: the Southern Annular Mode (SAM). It is regressed against indices with large interannual variability, and one of several trend indices in order to determine which trend term gives the optimum fit. We use SAM in sea-level pressure from station data in order to provide a long time series, from 1957 to 2005. The regression indices are stratospheric volcanic aerosol, solar activity, the quasi-biennial oscillation (QBO), the El Niño-Southern Oscillation, together with either a linear trend, or the effective equivalent stratospheric chlorine (EESC) that depletes polar ozone, or ozone mass deficit (OMD) in the Antarctic vortex. We find a statistically significant signal for volcanic aerosol, and, when the solar and QBO indices are represented by their product, a highly significant response to the product. We find a significant linear trend in SAM, but there is a major increase in significance using EESC 2 and a further increase using OMD. We make no direct attempt to identify cause and effect, but if the trend is due to human influence then ozone loss is at least 9 times more likely the principle cause of the trend in SAM than greenhouse gases, although we do not exclude greenhouse gases making a smaller contribution. Monthly and seasonal regressions show a maximum correlation with OMD between December and May (summer and autumn), consistent with previous work on stratospheric change as a cause of change in the troposphere.

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Simulation of Recent Southern Hemisphere Climate Change

Cited by 551 publications

References 29 publications

Variability and trends in the directional wave climate of the Southern Hemisphere

Variability and trends in the directional wave climate of the Southern Hemisphere

Changes in the ocean transport through Drake Passage during the 1980s and 1990s, forced by changes in the Southern Annular Mode

Influences of ozone depletion, the solar cycle and the QBO on the Southern Annular Mode

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