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tide gauge, satellite altimeter, and ocean general circulation model (OGCM) output to investigate the long-term variation and dynamics of the South Pacific sea level. Tide gauge observations are available for several decades in the South Pacific ( Goring and Bell 1999 ; Hannah 2004 ), but their locations are limited to coastal areas. Satellite data have a high spatial coverage, but the temporal availability of the satellite data alone is too short for the present purpose, as mentioned above. Sea
tide gauge, satellite altimeter, and ocean general circulation model (OGCM) output to investigate the long-term variation and dynamics of the South Pacific sea level. Tide gauge observations are available for several decades in the South Pacific ( Goring and Bell 1999 ; Hannah 2004 ), but their locations are limited to coastal areas. Satellite data have a high spatial coverage, but the temporal availability of the satellite data alone is too short for the present purpose, as mentioned above. Sea
mode), the second mode is the dipole pattern derived by Behera and Yamagata (2001) in the southern Indian Ocean (SIOD mode), and the last mode is the dipole of their South Pacific Ocean counterpart (SPOD mode), which was first identified by Huang and Shukla (2006) . Since they were identified, studies of the SAOD and SIOD modes have been conducted extensively, including simulations in coupled models, physical evolution, and growth/decay mechanisms ( Suzuki et al. 2004 ; Huang and Shukla 2008
mode), the second mode is the dipole pattern derived by Behera and Yamagata (2001) in the southern Indian Ocean (SIOD mode), and the last mode is the dipole of their South Pacific Ocean counterpart (SPOD mode), which was first identified by Huang and Shukla (2006) . Since they were identified, studies of the SAOD and SIOD modes have been conducted extensively, including simulations in coupled models, physical evolution, and growth/decay mechanisms ( Suzuki et al. 2004 ; Huang and Shukla 2008
the ocean dynamics are relatively linear and largely depend on air–sea interactions ( Penduff et al. 2011 ; Sérazin et al. 2015 ). Apart from these areas, the interior subtropical South Pacific (SP) exhibits relatively weak intrinsic variability of SSH at ~30°S, compared to that found in the other subtropical oceans ( Sérazin et al. 2015 ). In the subtropical SP, the Subtropical Countercurrent (STCC; Travis and Qiu 2017 ), initially called the South Tropical Countercurrent ( Merle et al. 1969
the ocean dynamics are relatively linear and largely depend on air–sea interactions ( Penduff et al. 2011 ; Sérazin et al. 2015 ). Apart from these areas, the interior subtropical South Pacific (SP) exhibits relatively weak intrinsic variability of SSH at ~30°S, compared to that found in the other subtropical oceans ( Sérazin et al. 2015 ). In the subtropical SP, the Subtropical Countercurrent (STCC; Travis and Qiu 2017 ), initially called the South Tropical Countercurrent ( Merle et al. 1969
–evaporation–SST feedback (reviewed by Xie 2004 ). SST anomalies are amplified by the positive feedback of high-albedo stratus clouds that form over cold water in the marine atmospheric boundary layer (MABL). Thus coastal SST is important for the whole ocean: cool SST along the Southern Hemisphere coast of South America initiates the meridional asymmetry of heating and the corresponding asymmetric atmospheric Hadley circulation over the Pacific Ocean. The asymmetry resulting from coupled coastal processes has
–evaporation–SST feedback (reviewed by Xie 2004 ). SST anomalies are amplified by the positive feedback of high-albedo stratus clouds that form over cold water in the marine atmospheric boundary layer (MABL). Thus coastal SST is important for the whole ocean: cool SST along the Southern Hemisphere coast of South America initiates the meridional asymmetry of heating and the corresponding asymmetric atmospheric Hadley circulation over the Pacific Ocean. The asymmetry resulting from coupled coastal processes has
1. Introduction Precipitating deep convection over the tropical ocean is observed to organize into large-scale regional rainbands, including zonally oriented bands such as the Pacific intertropical convergence zone (ITCZ) and tilted or diagonal bands such as the South Pacific convergence zone (SPCZ). Oriented along a northwest-to-southeast axis, the SPCZ extends from the equatorial western Pacific warm pool to the midlatitudes of the south central Pacific ( Trenberth 1976 ; Vincent 1994
1. Introduction Precipitating deep convection over the tropical ocean is observed to organize into large-scale regional rainbands, including zonally oriented bands such as the Pacific intertropical convergence zone (ITCZ) and tilted or diagonal bands such as the South Pacific convergence zone (SPCZ). Oriented along a northwest-to-southeast axis, the SPCZ extends from the equatorial western Pacific warm pool to the midlatitudes of the south central Pacific ( Trenberth 1976 ; Vincent 1994
in the Southern Hemisphere as in the Northern Hemisphere. Therefore, studies of STMWs in the Southern Hemisphere would improve not only our knowledge of Southern Hemisphere STMWs themselves, but also our understanding of factors influencing the basic features of STMWs in the world’s oceans. The western South Pacific Ocean has been observed more than the western South Atlantic Ocean and the southwest Indian Ocean. For example, the annual number of temperature observations at depths of 200 m in the
in the Southern Hemisphere as in the Northern Hemisphere. Therefore, studies of STMWs in the Southern Hemisphere would improve not only our knowledge of Southern Hemisphere STMWs themselves, but also our understanding of factors influencing the basic features of STMWs in the world’s oceans. The western South Pacific Ocean has been observed more than the western South Atlantic Ocean and the southwest Indian Ocean. For example, the annual number of temperature observations at depths of 200 m in the
in both sections in the north box ( Figs. 3a,b ) while it extends to the surface south of 22°S (Fig. 3c), consistent with the CARS climatology ( Ridgway and Dunn 2003 ). This outcrop was noted on the World Ocean Circulation Experiment (WOCE) 155°E section by Sokolov and Rintoul (2000) as being the boundary between the SPTW, with warm and salty characteristics of central/east Pacific origins ( Donguy 1994 ), and Subtropical Mode Water (STMW; θ = 14°–20°C), emanating from the north part of the
in both sections in the north box ( Figs. 3a,b ) while it extends to the surface south of 22°S (Fig. 3c), consistent with the CARS climatology ( Ridgway and Dunn 2003 ). This outcrop was noted on the World Ocean Circulation Experiment (WOCE) 155°E section by Sokolov and Rintoul (2000) as being the boundary between the SPTW, with warm and salty characteristics of central/east Pacific origins ( Donguy 1994 ), and Subtropical Mode Water (STMW; θ = 14°–20°C), emanating from the north part of the
. Qiu and Chen (2006) and Roemmich et al. (2007) observed a decadal spinup of the South Pacific Subtropical Gyre and attributed the spinup to an increased wind stress curl over the larger ocean basin during the 1990s. More recently, Zhang and Qu (2015) found that the gyre spinup has continued through the study period to 2013, causing an increase in SEC transport by 20%–30%. This spinup has a number of possible consequences for the STCC–SEC region. In addition to the changes in shearing caused
. Qiu and Chen (2006) and Roemmich et al. (2007) observed a decadal spinup of the South Pacific Subtropical Gyre and attributed the spinup to an increased wind stress curl over the larger ocean basin during the 1990s. More recently, Zhang and Qu (2015) found that the gyre spinup has continued through the study period to 2013, causing an increase in SEC transport by 20%–30%. This spinup has a number of possible consequences for the STCC–SEC region. In addition to the changes in shearing caused
across the SW Pacific waters south of the equator. The SPEArTC domain also includes the SPCZ region, plus the Coral Sea, the Tasman Sea, and the equatorial Pacific Ocean from east of the Maritime Continent to the Niño-3.4 region east of eastern Kiribati ( Fig. 1 ). b. Coupled ENSO index ENSO dominates seasonal to interannual climate variability in the Pacific region ( Philander 1990 ) and comprises two dynamically linked components. The atmospheric component (the Southern Oscillation) ( Walker and
across the SW Pacific waters south of the equator. The SPEArTC domain also includes the SPCZ region, plus the Coral Sea, the Tasman Sea, and the equatorial Pacific Ocean from east of the Maritime Continent to the Niño-3.4 region east of eastern Kiribati ( Fig. 1 ). b. Coupled ENSO index ENSO dominates seasonal to interannual climate variability in the Pacific region ( Philander 1990 ) and comprises two dynamically linked components. The atmospheric component (the Southern Oscillation) ( Walker and
in SSH and then its relation to subsurface changes in dynamic height and velocity observed in the decade between WOCE and Argo. Last, the decadal change in wind forcing is described. 2. The South Pacific decadal signal in sea surface height The maximum in zonally integrated ocean warming at 40°S was observed by Willis et al. (2004) in both subsurface temperature, 0–750 m, and in satellite SSH, which is dominated by thermosteric effects on interannual time scales. There are now 12 complete years
in SSH and then its relation to subsurface changes in dynamic height and velocity observed in the decade between WOCE and Argo. Last, the decadal change in wind forcing is described. 2. The South Pacific decadal signal in sea surface height The maximum in zonally integrated ocean warming at 40°S was observed by Willis et al. (2004) in both subsurface temperature, 0–750 m, and in satellite SSH, which is dominated by thermosteric effects on interannual time scales. There are now 12 complete years
