Influence of the South Pacific decadal variability on Southeast China rainfall during boreal autumn

2017 ◽  
Vol 38 ◽  
pp. e209-e223
Author(s):  
Gang Li ◽  
Jiepeng Chen ◽  
Xin Wang ◽  
Yanke Tan
Keyword(s):  
Decadal Variability ◽  
South Pacific ◽  
The South ◽  
Southeast China ◽  
Pacific Decadal Variability

scholarly journals Role of Stochastic Atmospheric Forcing from the South and North Pacific in Tropical Pacific Decadal Variability

2019 ◽  
Vol 32 (13) ◽  
pp. 4013-4038 ◽  
Author(s):  
Tianyi Sun ◽  
Yuko M. Okumura
Keyword(s):  
North Pacific ◽  
Large Scale ◽  
Decadal Variability ◽  
South Pacific ◽  
Tropical Pacific ◽  
Ocean Dynamics ◽  
The South ◽  
Pacific Decadal Variability ◽  
Sst Anomalies ◽  
The Tropical Pacific

Abstract Stochastic variability of internal atmospheric modes, known as teleconnection patterns, drives large-scale patterns of low-frequency SST variability in the extratropics. To investigate how the decadal component of this stochastically driven variability in the South and North Pacific affects the tropical Pacific and contributes to the observed basinwide pattern of decadal variability, a suite of climate model experiments was conducted. In these experiments, the models are forced with constant surface heat flux anomalies associated with the decadal component of the dominant atmospheric modes, particularly the Pacific–South American (PSA) and North Pacific Oscillation (NPO) patterns. Both the PSA and NPO modes induce basinwide SST anomalies in the tropical Pacific and beyond that resemble the observed interdecadal Pacific oscillation. The subtropical SST anomalies forced by the PSA and NPO modes propagate to the equatorial Pacific mainly through the wind–evaporation–SST feedback. This atmospheric bridge is stronger from the South Pacific than the North Pacific due to the northward displacement of the intertropical convergence zone and the associated northward advection of momentum anomalies. The equatorial ocean dynamics is also more strongly influenced by atmospheric circulation changes induced by the PSA mode than the NPO mode. In the PSA experiment, persistent and zonally coherent wind stress curl anomalies over the South Pacific affect the zonal mean depth of the equatorial thermocline and weaken the equatorial SST anomalies resulting from the atmospheric bridge. This oceanic adjustment serves as a delayed negative feedback and may be important for setting the time scales of tropical Pacific decadal variability.

Tropical Pacific Decadal Variability and ENSO Precursor in CMIP5 Models

2021 ◽  
Vol 34 (3) ◽  
pp. 1023-1045
Author(s):  
Yingying Zhao ◽  
Emanuele Di Lorenzo ◽  
Daoxun Sun ◽  
Samantha Stevenson
Keyword(s):  
Decadal Variability ◽  
South Pacific ◽  
Tropical Pacific ◽  
Cmip5 Models ◽  
The North ◽  
Enso Teleconnections ◽  
Pacific Decadal Variability ◽  
Basin Scale ◽  
The Tropics ◽  
North And South

AbstractObservational analyses suggest that a significant fraction of the tropical Pacific decadal variability (TPDV) (~60%–70%) is energized by the combined action of extratropical precursors of El Niño–Southern Oscillation (ENSO) originating from the North and South Pacific. Specifically, the growth and decay of the basin-scale TPDV pattern (time scale = ~1.5–2 years) is linked to the following sequence: ENSO precursors (extratropics, growth phase) → ENSO (tropics, peak phase) → ENSO successors (extratropics, decay phase) resulting from ENSO teleconnections. This sequence of teleconnections is an important physical basis for Pacific climate predictability. Here we examine the TPDV and its connection to extratropical dynamics in 20 models from phase 5 of the Coupled Model Intercomparison Project (CMIP). We find that most models (~80%) can simulate the observed spatial pattern (R > 0.6) and frequency characteristics of the TPDV. In 12 models, more than 65% of the basinwide Pacific decadal variability (PDV) originates from TPDV, which is comparable with observations (~70%). However, despite reproducing the basic spatial and temporal statistics, models underestimate the influence of the North and South Pacific ENSO precursors to the TPDV, and most of the models’ TPDV originates in the tropics. Only 35%–40% of the models reproduce the observed extratropical ENSO precursor patterns (R > 0.5). Models with a better representation of the ENSO precursors show 1) better basin-scale signatures of TPDV and 2) stronger ENSO teleconnections from/to the tropics that are consistent with observations. These results suggest that better representation of ENSO precursor dynamics in CMIP may lead to improved Pacific decadal variability dynamics and predictability.

Decadal Sea Level Variability in the South Pacific in a Global Eddy-Resolving Ocean Model Hindcast

2008 ◽  
Vol 38 (8) ◽  
pp. 1731-1747 ◽  
Author(s):  
Yoshi N. Sasaki ◽  
Shoshiro Minobe ◽  
Niklas Schneider ◽  
Takashi Kagimoto ◽  
Masami Nonaka ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
General Circulation ◽  
Decadal Variability ◽  
Southern Oscillation ◽  
Circulation Model ◽  
South Pacific ◽  
The South ◽  
Sea Level Variability ◽  
The Impact

Abstract Sea level variability and related oceanic changes in the South Pacific from 1970 to 2003 are investigated using a hindcast simulation of an eddy-resolving ocean general circulation model (OGCM) for the Earth Simulator (OFES), along with sea level data from tide gauges since 1970 and a satellite altimeter since 1992. The first empirical orthogonal function mode of sea level anomalies (SLAs) of OFES exhibits broad positive SLAs over the central and western South Pacific. The corresponding principal component indicates roughly stable high, low, and high SLAs, separated by a rapid sea level fall in the late 1970s and sea level rise in the late 1990s, consistent with tide gauge and satellite observations. These decadal changes are accompanied by circulation changes of the subtropical gyre at 1000-m depth, and changes of upper-ocean zonal current and eddy activity around the Tasman Front. In general agreement with previous related studies, it is found that sea level variations in the Tasman Sea can be explained by propagation of long baroclinic Rossby waves forced by wind stress curl anomalies, if the impact of New Zealand is taken into account. The corresponding atmospheric variations are associated with decadal variability of El Niño–Southern Oscillation (ENSO). Thus, decadal sea level variability in the western and central South Pacific in the past three and half decades and decadal ENSO variability are likely to be connected. The sea level rise in the 1990s, which attracted much attention in relation to the global warming, is likely associated with the decadal cooling in the tropical Pacific.

The South Pacific Pressure Trend Dipole and the Southern Blob

2021 ◽  
pp. 1-54
Author(s):  
René D. Garreaud ◽  
Kyle Clem ◽  
José Miguel Vicencio
Keyword(s):  
Decadal Variability ◽  
Storm Track ◽  
South Pacific ◽  
Southern Annular Mode ◽  
Hadley Cell ◽  
Positive Trend ◽  
West Antarctica ◽  
The South ◽  
Sea Level Pressure ◽  
The Tropics

AbstractDuring the last four decades, the sea level pressure has been decreasing over the Amundsen-Bellingshausen Sea (ABS) region and increasing between 30-40°S from New Zealand to Chile, thus forming a pressure trend dipole across the South Pacific. The trends are strongest in austral winter and have influenced the climate of West Antarctica and South America. The pressure trends have been attributed to decadal variability in the tropics, expansion of the Hadley cell and an associated positive trend of the Southern Annular Mode, but these mechanisms explain only about half of the pressure trend dipole intensity. Experiments conducted with two atmospheric models indicate that upper ocean warming over the subtropical southwest Pacific (SSWP), termed the Southern Blob, accounts for about half of the negative pressure trend in the ABS region and nearly all the ridging /drying over the eastern subtropical South Pacific, thus contributing to the central Chile megadrought. The SSWP warming intensifies the pressure trend dipole through warming the troposphere across the sub-tropical South Pacific and shifting the mid-latitude storm track poleward into the ABS. Multi-decadal periods of strong SSWP warming also appears in fully coupled pre-industrial simulations, associated with a pressure trend dipole and reduction in rainfall over the central tropical Pacific, thus suggesting a natural origin of the Southern Blob and its teleconnection. However, the current warming rate exceeds the range of natural variability, implying a likely additional anthropogenic contribution.

scholarly journals A Linear Inverse Model of Tropical and South Pacific Seasonal Predictability

2020 ◽  
Author(s):  
Jiale Lou ◽  
Terence O'Kane ◽  
Neil Holbrook
Keyword(s):  
Pacific Ocean ◽  
Decadal Variability ◽  
Southern Oscillation ◽  
South Pacific ◽  
Inverse Model ◽  
Deterministic System ◽  
The South ◽  
Seasonal Predictability ◽  
South Pacific Ocean ◽  
Linear Inverse Model

<p>A multivariate linear inverse model (LIM) is developed to demonstrate the mechanisms and seasonal predictability of the dominant modes of variability from the tropical and South Pacific Oceans. We construct a LIM whose covariance matrix is a combination of principal components derived from tropical and extra-tropical sea surface temperature, and South Pacific Ocean vertically-averaged temperature anomalies. Eigen-decomposition of the linear deterministic system yields stationary and/or propagating eigenmodes, of which the least damped modes resemble the El-Niño Southern Oscillation (ENSO) and the South Pacific Decadal Oscillation (SPDO). We show that although the oscillatory periods of ENSO and SPDO are distinct, they have very close damping time scales, indicating the predictive skill of the surface ENSO and SPDO is comparable. The most damped noise modes occur in the mid-latitude South Pacific Ocean, reflecting atmospheric eastward-propagating Rossby wave train variability. We argue that these ocean wave trains occur due to the atmospheric high-frequency variability of the Pacific South American pattern imprinting onto the surface ocean. The ENSO spring predictability barrier is apparent in LIM predictions initialized in Mar-May (MAM) but nevertheless displays significant correlation skill of up to ~3 months. For the SPDO, the predictability barrier tends to appear in June-September (JAS), indicating remote but delayed influences from the Tropics. We demonstrate that subsurface processes in the South Pacific Ocean are the main source of decadal variability, and further that by characterizing the upper ocean temperature contribution in the LIM the seasonal predictability of both ENSO and the SPDO variability is increased.</p>

Origins of Tropical Pacific Decadal Variability: Role of Stochastic Atmospheric Forcing from the South Pacific*

2013 ◽  
Vol 26 (24) ◽  
pp. 9791-9796 ◽  
Author(s):  
Yuko M. Okumura
Keyword(s):  
North Pacific ◽  
Decadal Variability ◽  
South Pacific ◽  
Atmospheric Model ◽  
Tropical Pacific ◽  
Ocean Dynamics ◽  
Atmospheric Forcing ◽  
The South ◽  
The North ◽  
The North Pacific

Abstract Based on the analysis of multicentury–millennium integrations of an atmospheric model coupled to the ocean with varying degrees, it is argued that ENSO-like decadal variability is primarily driven by stochastic atmospheric forcing. In particular, the leading mode of internal atmospheric variability over the South Pacific, which projects onto the Pacific–South American (PSA) pattern, plays an important role in modulating the trade winds and sea surface temperature (SST) in the southeast tropical Pacific. Subsequent ocean–atmosphere interactions organize a basinwide SST anomaly pattern in the tropics, which in turn forces atmospheric Rossby waves into the extratropics, reinforcing the PSA pattern and inducing coherent decadal changes in the North Pacific. In the absence of ocean dynamics, equatorial SST variability is reduced and the North Pacific exhibits decadal variability independent of the tropical–South Pacific. The strong tropical–South Pacific linkage may be attributed to the equatorially asymmetric nature of tropical Pacific climate.

scholarly journals South Pacific Decadal Climate Variability and Potential Predictability

2019 ◽  
Vol 32 (18) ◽  
pp. 6051-6069 ◽  
Author(s):  
Jiale Lou ◽  
Neil J. Holbrook ◽  
Terence J. O’Kane
Keyword(s):  
Pacific Decadal Oscillation ◽  
North Pacific ◽  
Decadal Variability ◽  
South Pacific ◽  
The South ◽  
Potential Predictability ◽  
The North ◽  
The Pacific ◽  
The Relationship ◽  
The North Pacific

Abstract The South Pacific decadal oscillation (SPDO) characterizes the Southern Hemisphere contribution to the Pacific-wide interdecadal Pacific oscillation (IPO) and is analogous to the Pacific decadal oscillation (PDO) centered in the North Pacific. In this study, upper ocean variability and potential predictability of the SPDO is examined in HadISST data and an atmosphere-forced ocean general circulation model. The potential predictability of the IPO-related variability is investigated in terms of both the fractional contribution made by the decadal component in the South, tropical and North Pacific Oceans and in terms of a doubly integrated first-order autoregressive (AR1) model. Despite explaining a smaller fraction of the total variance, we find larger potential predictability of the SPDO relative to the PDO. We identify distinct local drivers in the western subtropical South Pacific, where nonlinear baroclinic Rossby wave–topographic interactions act to low-pass filter decadal variability. In particular, we show that the Kermadec Ridge in the southwest Pacific enhances the decadal signature more prominently than anywhere else in the Pacific basin. Applying the doubly integrated AR1 model, we demonstrate that variability associated with the Pacific–South American pattern is a critically important atmospheric driver of the SPDO via a reddening process analogous to the relationship between the Aleutian low and PDO in the North Pacific—albeit that the relationship in the South Pacific appears to be even stronger. Our results point to the largely unrecognized importance of South Pacific processes as a key source of decadal variability and predictability.

scholarly journals A Linear Inverse Model of Tropical and South Pacific Seasonal Predictability

2020 ◽  
Vol 33 (11) ◽  
pp. 4537-4554 ◽  
Author(s):  
Jiale Lou ◽  
Terence J. O’Kane ◽  
Neil J. Holbrook
Keyword(s):  
Pacific Ocean ◽  
Decadal Variability ◽  
Southern Oscillation ◽  
South Pacific ◽  
Inverse Model ◽  
Deterministic System ◽  
The South ◽  
Seasonal Predictability ◽  
South Pacific Ocean ◽  
Linear Inverse Model

AbstractA multivariate linear inverse model (LIM) is developed to demonstrate the mechanisms and seasonal predictability of the dominant modes of variability from the tropical and South Pacific Oceans. We construct a LIM whose covariance matrix is a combination of principal components derived from tropical and extratropical sea surface temperature, and South Pacific Ocean vertically averaged temperature anomalies. Eigen-decomposition of the linear deterministic system yields stationary and/or propagating eigenmodes, of which the least damped modes resemble El Niño–Southern Oscillation (ENSO) and the South Pacific decadal oscillation (SPDO). We show that although the oscillatory periods of ENSO and SPDO are distinct, they have very close damping time scales, indicating that the predictive skill of the surface ENSO and SPDO is comparable. The most damped noise modes occur in the midlatitude South Pacific Ocean, reflecting atmospheric eastward-propagating Rossby wave train variability. We argue that these ocean wave trains occur due to the high-frequency atmospheric variability of the Pacific–South American pattern imprinting onto the surface ocean. The ENSO spring predictability barrier is apparent in LIM predictions initialized in March–May (MAM) but displays a significant correlation skill of up to ~3 months. For the SPDO, the predictability barrier tends to appear in June–September (JAS), indicating remote but delayed influences from the tropics. We demonstrate that subsurface processes in the South Pacific Ocean are the main source of decadal variability and further that by characterizing the upper ocean temperature contribution in the LIM, the seasonal predictability of both ENSO and the SPDO variability is increased.

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