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1. Introduction Decadal variability denotes temporal fluctuations on time scales ranging from one to a few decades. It has been observed in various regions including the Atlantic, Pacific, and Indian Oceans ( Latif and Barnett 1996 ; Zhang et al. 1997 ; Alexander 2010 ; Liu 2012 ; Han et al. 2014 ). The causes of decadal variability involve contributions from both natural external forcings like volcanic eruptions ( Domingues et al. 2008 ; Liu et al. 2022 ) and natural internal
1. Introduction Decadal variability denotes temporal fluctuations on time scales ranging from one to a few decades. It has been observed in various regions including the Atlantic, Pacific, and Indian Oceans ( Latif and Barnett 1996 ; Zhang et al. 1997 ; Alexander 2010 ; Liu 2012 ; Han et al. 2014 ). The causes of decadal variability involve contributions from both natural external forcings like volcanic eruptions ( Domingues et al. 2008 ; Liu et al. 2022 ) and natural internal
are well suited to detect their variability in a systematic way. The present study has three objectives. The first is to describe the time-varying NEC bifurcation along the Philippine coast based on the 17-yr satellite altimeter data. Well-defined, quasi-decadal changes with a peak-to-peak amplitude exceeding 5° latitude are detected. The second objective is to examine the dynamics underlying the observed bifurcation changes. This is pursued by adopting a 1 ½-layer reduced-gravity model forced by
are well suited to detect their variability in a systematic way. The present study has three objectives. The first is to describe the time-varying NEC bifurcation along the Philippine coast based on the 17-yr satellite altimeter data. Well-defined, quasi-decadal changes with a peak-to-peak amplitude exceeding 5° latitude are detected. The second objective is to examine the dynamics underlying the observed bifurcation changes. This is pursued by adopting a 1 ½-layer reduced-gravity model forced by
averaged over the period 1991–2010 presented as anomalies relative to the period 1971–90. (b) The corresponding zonal-mean temperature anomalies. While the Northern Hemisphere experienced a strong warming during the recent decades, the Southern Hemisphere warmed only little. The global-average SST difference between the two time periods amounts to 0.2°C. Climate variability can be either generated internally by interactions within or between the individual climate system components (e.g., atmosphere
averaged over the period 1991–2010 presented as anomalies relative to the period 1971–90. (b) The corresponding zonal-mean temperature anomalies. While the Northern Hemisphere experienced a strong warming during the recent decades, the Southern Hemisphere warmed only little. The global-average SST difference between the two time periods amounts to 0.2°C. Climate variability can be either generated internally by interactions within or between the individual climate system components (e.g., atmosphere
1. Introduction In line with the great volume of the Southern Hemisphere (SH) oceans, the South Pacific Ocean exhibits prominent decadal climate variability (e.g., Reason 2000 ). That said, our understanding of Pacific and in particular South Pacific decadal variability and predictability has been limited, despite this being an emerging area of substantial interest and active research ( Meehl et al. 2014 ; Holbrook et al. 2014 ; Power et al. 2017 ). The lack of consistent long
1. Introduction In line with the great volume of the Southern Hemisphere (SH) oceans, the South Pacific Ocean exhibits prominent decadal climate variability (e.g., Reason 2000 ). That said, our understanding of Pacific and in particular South Pacific decadal variability and predictability has been limited, despite this being an emerging area of substantial interest and active research ( Meehl et al. 2014 ; Holbrook et al. 2014 ; Power et al. 2017 ). The lack of consistent long
1. Introduction Decadal means are a popular statistic for decadal climate variability (e.g., Watanabe et al. 2014 ; Allen et al. 2013 ; Knight 2009 ; Watterson and Whetton 2011 ). Climate scenarios, such as in the Intergovernmental Panel on Climate Change assessment reports, also use decadal mean variables as the baseline of future climate. Therefore, it is crucial to better understand the uncertainty, predictability, and drivers of the decadal mean variables. In decadal climate variability
1. Introduction Decadal means are a popular statistic for decadal climate variability (e.g., Watanabe et al. 2014 ; Allen et al. 2013 ; Knight 2009 ; Watterson and Whetton 2011 ). Climate scenarios, such as in the Intergovernmental Panel on Climate Change assessment reports, also use decadal mean variables as the baseline of future climate. Therefore, it is crucial to better understand the uncertainty, predictability, and drivers of the decadal mean variables. In decadal climate variability
1. Introduction Decadal and multidecadal climate variability has been a topic of interest for a number of decades. It has been studied in observations (e.g., Zhang et al. 1997 ; Delworth and Mann 2000 ; Sutton and Hodson 2005 ; Parker et al. 2007 ; Schubert et al. 2009 ; Liu 2012 and references therein; Zheng and Frederiksen 2021 ) and in climate models (e.g., Delworth et al. 1993 ; Mann et al. 1995 ; Knight et al. 2005 ; Delworth et al. 2007 ; Knight 2009 ; Frederiksen et al
1. Introduction Decadal and multidecadal climate variability has been a topic of interest for a number of decades. It has been studied in observations (e.g., Zhang et al. 1997 ; Delworth and Mann 2000 ; Sutton and Hodson 2005 ; Parker et al. 2007 ; Schubert et al. 2009 ; Liu 2012 and references therein; Zheng and Frederiksen 2021 ) and in climate models (e.g., Delworth et al. 1993 ; Mann et al. 1995 ; Knight et al. 2005 ; Delworth et al. 2007 ; Knight 2009 ; Frederiksen et al
1. Introduction Sea surface temperatures (SSTs) in the Pacific Ocean region have distinct decadal to interdecadal variability ( Mantua et al. 1997 ; Zhang et al. 1997 ; Power et al. 1999 ). Pacific decadal variability is characterized by subtropical gyre spatial patterns throughout the North and South Pacific that are in phase with each other and out of phase with the eastern and central equatorial Pacific ( Deser et al. 2004 ; Han et al. 2014 ; Newman et al. 2016 ). Especially, the
1. Introduction Sea surface temperatures (SSTs) in the Pacific Ocean region have distinct decadal to interdecadal variability ( Mantua et al. 1997 ; Zhang et al. 1997 ; Power et al. 1999 ). Pacific decadal variability is characterized by subtropical gyre spatial patterns throughout the North and South Pacific that are in phase with each other and out of phase with the eastern and central equatorial Pacific ( Deser et al. 2004 ; Han et al. 2014 ; Newman et al. 2016 ). Especially, the
) variability in precipitation across North America using a set of gridded instrumental precipitation records. Most prior studies of D2M variability in instrumental records of drought or precipitation have focused on identifying spatially coherent patterns and used data processed to emphasize variations at those time scales (e.g., Enfield et al. 2001 ; McCabe et al. 2004 ; McCabe and Palecki 2006 ). We adopt a complimentary approach that compares the amount of variance in decadal and multidecadal bands
) variability in precipitation across North America using a set of gridded instrumental precipitation records. Most prior studies of D2M variability in instrumental records of drought or precipitation have focused on identifying spatially coherent patterns and used data processed to emphasize variations at those time scales (e.g., Enfield et al. 2001 ; McCabe et al. 2004 ; McCabe and Palecki 2006 ). We adopt a complimentary approach that compares the amount of variance in decadal and multidecadal bands
linked to jet variability. For example, the recent unusual jet winters also exhibited strong but distinct blocking anomalies, with the 2009/10 jet being shifted south of blocking over Greenland and the 2011/12 jet shifted north of blocking over southwest Europe ( Santos et al. 2013 ). Hence, we show that decadal increases in jet position variability are linked to increased blocking over both Greenland and parts of Europe. These basinwide variations in blocking have been implicated in contributing to
linked to jet variability. For example, the recent unusual jet winters also exhibited strong but distinct blocking anomalies, with the 2009/10 jet being shifted south of blocking over Greenland and the 2011/12 jet shifted north of blocking over southwest Europe ( Santos et al. 2013 ). Hence, we show that decadal increases in jet position variability are linked to increased blocking over both Greenland and parts of Europe. These basinwide variations in blocking have been implicated in contributing to
al. (2016) also suggested that the cooling over the central to eastern Pacific plays an important role in maintaining the WNPAC during the developing years of La Niña. Previous studies of the WNPAC have mainly focused on its interannual variability; however, decadal variability of the WNPAC has not been documented and investigated. Recent studies suggested that the western Pacific subtropical high (WPSH), which is linked with the WNPAC, has experienced decadal changes ( Gong and Ho 2002 ). Zhou
al. (2016) also suggested that the cooling over the central to eastern Pacific plays an important role in maintaining the WNPAC during the developing years of La Niña. Previous studies of the WNPAC have mainly focused on its interannual variability; however, decadal variability of the WNPAC has not been documented and investigated. Recent studies suggested that the western Pacific subtropical high (WPSH), which is linked with the WNPAC, has experienced decadal changes ( Gong and Ho 2002 ). Zhou
