Role of the South Pacific Convergence Zone in West Antarctic Decadal Climate Variability

Clem, Kyle R.; Lintner, Benjamin R.; Broccoli, Anthony J.; Miller, James R.

doi:10.1029/2019gl082108

Cited by 27 publications

(40 citation statements)

References 52 publications

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“…4d and 8a), the jet experiences an intensification in the South Pacific with a deepened Amundsen Sea low (ASL), compared to the poleward movement in the South Atlantic and southern Indian Ocean basins. While previous studies have suggested that the negative IPO could largely explain the deepened ASL in the austral cool seasons, through an anomalous stationary Rossby wave response, similar analysis for the austral summer season leads to a weakened ASL, opposite to that observed (Meehl et al 2016;Clem et al 2019). Therefore, further work is needed to understand the zonally asymmetric jet strengthening in the South Pacific basin.…”

Section: Discussionmentioning

confidence: 87%

“…Some research has related the interdecadal Pacific oscillation (IPO) transition in the late 1990s to Antarctic climate variability. For example, the negative phase of the IPO has been linked to Antarctic sea ice expansion via a positive phase of the SAM combined with a deepened Amundsen Sea low (ASL), which alters the wind patterns over the Antarctic sea ice zone (Meehl et al 2016;Purich et al 2016;Clem et al 2019;Holland et al 2019;Meehl et al 2019b). Recent studies have also highlighted the role of Atlantic and Indian Ocean SSTs on Antarctic climate.…”

Section: Introductionmentioning

confidence: 99%

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Role of Tropical Variability in Driving Decadal Shifts in the Southern Hemisphere Summertime Eddy-Driven Jet

et al. 2020

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The Southern Hemisphere summertime eddy-driven jet and storm tracks have shifted poleward over the recent few decades. In previous studies, explanations have mainly stressed the influence of external forcing in driving this trend. Here we examine the role of internal tropical SST variability in controlling the austral summer jet’s poleward migration, with a focus on interdecadal time scales. The role of external forcing and internal variability are isolated by using a hierarchy of Community Earth System Model version 1 (CESM1) simulations, including the pre-industrial control, large ensemble, and pacemaker runs. Model simulations suggest that in the early twenty-first century, both external forcing and internal tropical Pacific SST variability are important in driving a positive southern annular mode (SAM) phase and a poleward migration of the eddy-driven jet. Tropical Pacific SST variability, associated with the negative phase of the interdecadal Pacific oscillation (IPO), acts to shift the jet poleward over the southern Indian and southwestern Pacific Oceans and intensify the jet in the southeastern Pacific basin, while external forcing drives a significant poleward jet shift in the South Atlantic basin. In response to both external forcing and decadal Pacific SST variability, the transient eddy momentum flux convergence belt in the middle latitudes experiences a poleward migration due to the enhanced meridional temperature gradient, leading to a zonally symmetric southward migration of the eddy-driven jet. This mechanism distinguishes the influence of the IPO on the midlatitude circulation from the dynamical impact of ENSO, with the latter mainly promoting the subtropical wave-breaking critical latitude poleward and pushing the midlatitude jet to higher latitudes.

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Section: Discussionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Role of Tropical Variability in Driving Decadal Shifts in the Southern Hemisphere Summertime Eddy-Driven Jet

et al. 2020

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“…Despite the long-term warming trend, recent studies also show the existence of a regional cooling trend in some parts of Antarctica, including the Antarctic Peninsula, since the late 1990s (Carrasco, 2013;Turner et al, 2016;Oliva et al, 2017). However, this recent cooling period on the peninsula does not yet represent a shift in the overall robust warming trend, and is instead attributed to internal climate variability Gonzalez and Fortuny, 2018;Clem et al, 2019;Jones et al, 2019). The persistent windward warming trend in the autumn season as well as at the annual time scale during the recent cooling period could lead to important implications for the fate of ice sheet surfaces on the windward coasts.…”

Section: Summary and Concluding Remarksmentioning

confidence: 99%

Recent Near-surface Temperature Trends in the Antarctic Peninsula from Observed, Reanalysis and Regional Climate Model Data

et al. 2020

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This study investigates the recent near-surface temperature trends over the Antarctic Peninsula. We make use of available surface observations, ECMWF's ERA5 and its predecessor ERA-Interim, as well as numerical simulations, allowing us to contrast different data sources. We use hindcast simulations performed with Polar-WRF over the Antarctic Peninsula on a nested domain configuration at 45 km (PWRF-45) and 15 km (PWRF-15) spatial resolutions for the period 1991−2015. In addition, we include hindcast simulations of KNMI-RACMO21P obtained from the CORDEX-Antarctica domain (~50 km) for further comparisons. Results show that there is a marked windward warming trend except during summer. This windward warming trend is particularly notable in the autumn season and likely to be associated with the recent deepening of the Amundsen/Bellingshausen Sea low and warm advection towards the Antarctic Peninsula. On the other hand, an overall summer cooling is characterized by the strengthening of the Weddell Sea low as well as an anticyclonic trend over the Amundsen Sea accompanied by northward winds. The persistent cooling trend observed at the Larsen Ice Shelf station is not captured by ERA-Interim, whereas hindcast simulations indicate that there is a clear pattern of windward warming and leeward cooling. Furthermore, larger temporal correlations and lower differences exhibited by PWRF-15 illustrate the existence of the added value in the higher spatial resolution simulation.

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“…The South Pacific Convergence Zone (SPCZ), a convective cloud band stretching from the Western Pacific Warm Pool toward French Polynesia (Trenberth, 1976; D. G. Vincent, 1994), is the largest rain band in the world during austral summer (December–February). The extensive and pervasive nature of this climate feature means the SPCZ plays a major role in South Pacific cyclogenesis and rainfall (E. M. Vincent et al, 2011) and a significant role in global‐scale circulation (D. G. Vincent, 1994), influencing the ocean freshwater budget, cross‐equatorial flow (Lorrey et al, 2012; Matthews, 2012), and circulation patterns across the southern oceans (Clem et al, 2019; Clem & Renwick, 2015). The presence and northwest‐southeast orientation of the SPCZ is controlled by underlying sea surface temperature (SST) gradients (van der Wiel et al, 2016; Widlansky et al, 2011), which determine the near‐surface wind conditions that result in low‐level moisture convergence (Ganachaud, 2014).…”

Section: Introductionmentioning

confidence: 99%

One Thousand Three Hundred Years of Variability in the Position of the South Pacific Convergence Zone

Higgins

Palmer

Turney

et al. 2020

Geophysical Research Letters

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The South Pacific Convergence Zone (SPCZ) is the largest rain belt in the Southern Hemisphere and a key driver of precipitation variability, impacting South Pacific island communities. Our millennial‐long reconstruction is based on a trans‐Pacific tree‐ring network, containing chronologies sensitive to changes in the SPCZ because of its pervasive nature, spatial extent, and link to the El Niño‐Southern Oscillation. The reconstruction explains 58% of variance in the instrumental SPCZ index from 1911–1998. El Niño‐Southern Oscillation cycles are identified throughout the reconstruction period. Multidecadal periodicities wax and wane, coinciding with a sustained eastward shift during the Medieval Climate Anomaly (~1,000–1,200 CE). We find large volcanic eruptions increased the tendency for the SPCZ to be displaced eastward. The reconstruction helps improve our understanding of past hydroclimatic behavior in the southwest Pacific and can be used to validate general circulation model projections for Pacific Island communities and the wider region in the 21st century.

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Role of the South Pacific Convergence Zone in West Antarctic Decadal Climate Variability

Cited by 27 publications

References 52 publications

Role of Tropical Variability in Driving Decadal Shifts in the Southern Hemisphere Summertime Eddy-Driven Jet

Role of Tropical Variability in Driving Decadal Shifts in the Southern Hemisphere Summertime Eddy-Driven Jet

Recent Near-surface Temperature Trends in the Antarctic Peninsula from Observed, Reanalysis and Regional Climate Model Data

One Thousand Three Hundred Years of Variability in the Position of the South Pacific Convergence Zone

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