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A novel methodology has been presented for objectively identifying the PSA pattern. By rotating the global coordinate system such that the equator (a great circle path) traces the approximate path of the PSA pattern, the method was able to utilize Fourier analysis to quantify the phase and amplitude of wave-like variability in the PSA sector. The climatology produced from the application of this method revealed that the PSA pattern often persists for months at a time. There was an almost equal split between events that propagate (to the east) and those that remain relatively stationary, and the pattern is most active during winter and spring. The pattern has a strong influence on temperature and precipitation variability over West Antarctica and the Antarctic Peninsula, and on sea ice variability in the adjacent Amundsen, Bellingshausen and Weddell Seas.   In reconciling the results of the Fourier analysis with existing EOF-based definitions of the PSA pattern, a strong resemblance was found between the existing PSA-1 mode and the spatial pattern corresponding to the bimodal phase peaks of wavenumber 5-6 dominant variability in the PSA sector. The lack of a higher-order, multi-modal phase distribution may explain the degenerate nature of the existing PSA-2 mode (and the difficulty that researchers have had in identifying a tropical driver of that mode). It would appear that together, the degenerate EOF-2 / EOF-3 pair (e.g. Figure \ref{fig:eof}) may simply represent the remaining wavenumber 5-6 5--6  variability in the PSA sector, which likely comprises of contributions from the hemispheric zonal wavenumber three pattern as well as isolated Amundsen Sea Low and Antarctic Dipole variability. By using the bimodal phase peaks as a means to define PSA pattern activity, it was possible to identify a trend towards the negative phase of the pattern over the period 1979-2014 1979--2014  on an annual basis and also during summer, autumn and winter. This autumn trend (and the high latitude temperature and sea ice anomalies associated with the negative phase of the PSA pattern) is consistent with the work of \citet{Ding2013}, who found that autumn warming over the Antarctic Peninsula and associated sea ice declines over the Bellingshausen Sea are associated with an atmospheric circulation resembling the negative phase of the PSA pattern. While this explanation makes sense on the eastern flank of the central circulation anomaly associated with that pattern, the negative phase of the PSA pattern is also associated with strong cooling over West Antarctica. Autumn temperature declines have not been observed in that region, and thus our results suggest that the PSA-related cooling must have been offset by other factors. In contrast to the autumn warming over the Antarctic Peninsula, winter warming over West Antarctica has been associated with an atmospheric circulation resembling the positive phase of the PSA pattern \citep{Ding2011}. Our climatology revealed a (albeit non-significant) trend towards the negative phase of the PSA pattern during winter, which raises the question: how is it that winter temperature trends over West Antarctica are associated with an atmospheric circulation resembling the positive phase of the PSA pattern, but a climatology of PSA pattern activity does not reveal trends consistent with that finding? One possible answer to this question comes from \citet{Li2015a}. They analyzed Rossby wave trains associated with observed SST trends in the tropical Atlantic, tropical Indian, west Pacific and east Pacific regions and found that all four have a center of action over the Amundsen Sea. While none of these individual wave trains resembled the PSA pattern, a linear combination of the four of them did (with the tropical Atlantic and west Pacific identified as most influential). In other words, the integrated influence of tropical SST trends on the atmospheric circulation resembles the positive phase of the PSA pattern, but the waves underpinning that teleconnection do not. This result is consistent with earlier studies that identified the tropical Atlantic as a driver of recent trends in West Antarctica \citep{Li2014,Simpkins2014}. Another possible answer comes from \citet{Fogt2015}, who suggest that radiative forcing has played a role in Amundsen Sea Low trends that are consistent with warming in West Antarctica.