caa a22 4500 605472580 CHVBK 20210128100338.0 cr unu---uuuuu 210128e20151201xx s 000 0 eng 10.1007/s00382-015-2525-1 doi (NATIONALLICENCE)springer-10.1007/s00382-015-2525-1 A Tripole Index for the Interdecadal Pacific Oscillation [Elektronische Daten] [Benjamin Henley, Joelle Gergis, David Karoly, Scott Power, John Kennedy, Chris Folland] A new index is developed for the Interdecadal Pacific Oscillation, termed the IPO Tripole Index (TPI). The IPO is associated with a distinct ‘tripole' pattern of sea surface temperature anomalies (SSTA), with three large centres of action and variations on decadal timescales, evident in the second principal component (PC) of low-pass filtered global SST. The new index is based on the difference between the SSTA averaged over the central equatorial Pacific and the average of the SSTA in the Northwest and Southwest Pacific. The TPI is an easily calculated, non-PC-based index for tracking decadal SST variability associated with the IPO. The TPI time series bears a close resemblance to previously published PC-based indices and has the advantages of being simpler to compute and more consistent with indices used to track the El Niño-Southern Oscillation (ENSO), such as Niño 3.4. The TPI also provides a simple metric in physical units of °C for evaluating decadal and interdecadal variability of SST fields in a straightforward manner, and can be used to evaluate the skill of dynamical decadal prediction systems. Composites of SST and mean sea level pressure anomalies reveal that the IPO has maintained a broadly stable structure across the seven most recent positive and negative epochs that occurred during 1870-2013. The TPI is shown to be a robust and stable representation of the IPO phenomenon in instrumental records, with relatively more variance in decadal than shorter timescales compared to Niño 3.4, due to the explicit inclusion of off-equatorial SST variability associated with the IPO. Springer-Verlag Berlin Heidelberg, 2015 Interdecadal Pacific Oscillation nationallicence Pacific Decadal Oscillation nationallicence Pacific Decadal Variability nationallicence IPO nationallicence PDO nationallicence PDV nationallicence TPI nationallicence Henley Benjamin School of Earth Sciences, University of Melbourne, Parkville, Australia aut Gergis Joelle School of Earth Sciences, University of Melbourne, Parkville, Australia aut Karoly David School of Earth Sciences, University of Melbourne, Parkville, Australia aut Power Scott Centre for Australian Weather and Climate Research, Bureau of Meteorology, Melbourne, Australia aut Kennedy John Met Office Hadley Centre, Exeter, UK aut Folland Chris Met Office Hadley Centre, Exeter, UK aut Climate Dynamics Springer Berlin Heidelberg 45/11-12(2015-12-01), 3077-3090 0930-7575 45:11-12<3077 2015 45 382 https://doi.org/10.1007/s00382-015-2525-1 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00382-015-2525-1 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Henley Benjamin School of Earth Sciences, University of Melbourne, Parkville, Australia aut NATIONALLICENCE 700 1- Gergis Joelle School of Earth Sciences, University of Melbourne, Parkville, Australia aut NATIONALLICENCE 700 1- Karoly David School of Earth Sciences, University of Melbourne, Parkville, Australia aut NATIONALLICENCE 700 1- Power Scott Centre for Australian Weather and Climate Research, Bureau of Meteorology, Melbourne, Australia aut NATIONALLICENCE 700 1- Kennedy John Met Office Hadley Centre, Exeter, UK aut NATIONALLICENCE 700 1- Folland Chris Met Office Hadley Centre, Exeter, UK aut NATIONALLICENCE 773 0- Climate Dynamics Springer Berlin Heidelberg 45/11-12(2015-12-01), 3077-3090 0930-7575 45:11-12<3077 2015 45 382