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Willem P. Sijp and Matthew H. England

; Seidov and Haupt 2002 ), and is thought to arise from net evaporation in the Atlantic ( Warren 1983 ) and the THC itself ( Manabe and Stouffer 1988 ). Exchange of thermocline water between basins is controlled by the Antarctic Circumpolar Current (ACC), a mighty current that is strongly linked with the Southern Hemisphere (SH) subpolar westerly winds (SWWs). The location of the fronts at its northern boundary controls the warm, saline influence of Indian Ocean thermocline water resulting from the

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Everson D. Piva, Manoel A. Gan, and V. Brahmananda Rao

1. Introduction Even a cursory analysis of the geopotential height in the mid- and upper troposphere shows the presence of waves with wavelengths varying from planetary scale to mesoscale. These waves have a fundamental role in maintaining the heat, momentum, and moisture balance and might generate cyclones at the surface level. In general, the initial formation of surface cyclones or cyclogenesis in the Southern Hemisphere (SH) occurs between 35° and 55°S. The matured systems are found between

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Lindsey N. Williams, Sukyoung Lee, and Seok-Woo Son

1. Introduction One peculiar feature in the atmosphere, which does not seem to have received much attention, is the fact that large-scale westerly jets, at times, take on a spiral form. An example of the spiral jet structure is shown in Fig. 1 , which displays the 275-hPa Southern Hemisphere (SH) zonal wind field, corresponding approximately to a 40-yr calendar mean of 27 April. A more precise description of the data and averaging procedure will be given in section 2 . Starting from the

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Xiaogu Zheng and Carsten S. Frederiksen

estimating, from monthly mean data, spatial patterns of the slow and intraseasonal components. This methodology provides a way to better identify and understand the sources of predictive skill as well as the sources of uncertainty in climate variability. By applying this methodology to reanalysis datasets, they successfully identified the potentially predictable and unpredictable patterns of the 500-hPa geopotential height field for the Northern Hemisphere ( Frederiksen and Zheng 2004 ) and the Southern

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Li Dong, Timothy J. Vogelsang, and Stephen J. Colucci

region such that blocking is suppressed during the warm phase of ENSO. In contrast to the Northern Hemisphere (NH), Renwick (1998) found that the number of days of blocking tends to increase on average during the warm phase of ENSO cycle, particularly over the southeast Pacific during the southern spring and summer, using a 16-yr record of 500-hPa height field data. This result is not only confirmed by the updated work of Renwick and Revell (1999) , using a 39-yr record of 500-hPa height dataset

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Takafumi Miyasaka and Hisashi Nakamura

boundary currents and cool equatorward currents off the west coasts of the continents. The strong equatorward alongshore winds to the east of the anticyclones also contribute to the maintenance of underlying cool sea surface temperatures (SSTs) by enhancing surface evaporation, coastal upwelling, and entrainment at the bottom of the oceanic mixed layer. In the Southern Hemisphere (SH), as well, the summertime surface subtropical anticyclones are in a cell-type configuration (as shown below), suggesting

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Francis Codron

1. Introduction Quasi-annular patterns, often called annular modes, dominate atmospheric extratropical low-frequency variability ( Thompson and Wallace 1998 ). For both hemispheres, these modes are characterized by pressure anomalies of one sign over the polar region, surrounded by a band of opposing polarity with peak amplitude in the midlatitudes. They also appear as the favored response to a wide range of climate forcings, such as the observed trend in the Southern Hemisphere ( Thompson and

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Harry H. Hendon, David W. J. Thompson, and Matthew C. Wheeler

1. Introduction The Northern and Southern Hemisphere annular modes play a prominent role in the climate of their respective hemispheres. Both modes are characterized by approximately zonally symmetric, equivalent barotropic seesaws in the strength of the zonal flow between ∼55°–60° and ∼35°–40° latitude. The structure of the Southern Hemisphere annular mode (SAM; also referred to as the Antarctic Oscillation or High Latitude Mode) is documented in, for example, Trenberth (1979) , Rogers and

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Ian Simmonds, Kevin Keay, and John Arthur Tristram Bye

personal biases and prejudices. To make matters even more complex, a number of studies have shown that the diagnoses of Southern Hemisphere (SH) synoptic systems (of central interest here) in different reanalyses are often considerably at variance (e.g., Bromwich et al. 2007 ). The concept of a front dates back to the work of Bjerknes (1919) and can be understood in its simplest form as a (sloping) quasi-discontinuity in the density field. Over the twentieth century the concept was progressively

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A. J. Meijers, N. L. Bindoff, and J. L. Roberts

transport is largely restricted to the upper-ocean layers. An analysis of eddy heat and freshwater transport in the Southern Hemisphere of a high-resolution global ocean model is the focus of this study. A description of the numerical model used is presented in section 2 . The modeled horizontal and meridional mean volume transport streamfunctions are presented in section 3 , along with a summary of important heat and freshwater transports. These indicate that the model largely replicates the known

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