Decadal Variability of Southern Subtropical SST Wavenumber‐4 Pattern and Its Impact

Senapati, Balaji; Dash, Mihir Kumar; Behera, Swadhin K.

doi:10.1029/2022gl099046

Cited by 3 publications

(5 citation statements)

References 37 publications

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“…However, it will be interesting to quantify the amount of precipitation/diabatic heating over the SWSP that is necessary for the generation of the W4 pattern. The role of the tropical climate in the W4 pattern on a decadal timescale (which is related to SPMM; Senapati et al., 2022) and the linkage of the Tasman Sea with tropical regions (Liess et al., 2014) cannot be neglected. In the absence of tropical climate variation, the W4 pattern can be generated, but tropical climate variability may play a role in modulating the W4 pattern through atmospheric teleconnection and changes in local SST over the Tasman Sea, which will be studied in the future.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…It is noted that thermodynamic feedbacks between meridional wind, surface heat flux, and mixed layer mainly cause the SST‐W4 pattern. The SST‐W4 pattern also undergoes a decadal variability and impacts the precipitation over Southern continents (Senapati et al., 2022). The SST footprints of the decadal variability of the South Pacific Meridional Mode (SPMM; Zhang et al., 2014) create an ideal environment for the frequent occurrence of positive/negative type of the SST‐W4 pattern, which results in the decadal modulation of the SST‐W4 pattern after 2 years (Senapati et al., 2022).…”

Section: Introductionmentioning

confidence: 99%

“…The SST‐W4 pattern also undergoes a decadal variability and impacts the precipitation over Southern continents (Senapati et al., 2022). The SST footprints of the decadal variability of the South Pacific Meridional Mode (SPMM; Zhang et al., 2014) create an ideal environment for the frequent occurrence of positive/negative type of the SST‐W4 pattern, which results in the decadal modulation of the SST‐W4 pattern after 2 years (Senapati et al., 2022). The SPMM, which drives the decadal variability of SST‐W4 (Senapati et al., 2022), has been considered as a precursor to ENSO dynamics (Larson et al., 2018; You & Furtado, 2018).…”

Section: Introductionmentioning

confidence: 99%

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Southern Hemisphere Circumpolar Wavenumber‐4 Pattern Simulated in SINTEX‐F2 Coupled Model

Senapati,

Morioka,

Behera

et al. 2024

JGR Oceans

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Interannual sea surface temperature (SST) variations in the subtropical‐midlatitude Southern Hemisphere are often associated with a circumpolar wavenumber‐4 (W4) pattern. This study is the first attempt to successfully simulate the SST‐W4 pattern using a state‐of‐the‐art coupled model called SINTEX‐F2 and clarify the underlying physical processes. It is found that the SST variability in the southwestern subtropical Pacific (SWSP) plays a key role in triggering atmospheric variability and generating the SST‐W4 pattern during austral summer (December‐February). In contrast, the tropical SST variability has a very limited effect. The anomalous convection and associated divergence over the SWSP induce atmospheric Rossby waves confined in the westerly jet. Then, the synoptic disturbances circumnavigate the subtropical Southern Hemisphere, establishing an atmospheric W4 pattern. The atmospheric W4 pattern has an equivalent barotropic structure in the troposphere, and it interacts with the upper ocean, causing variations in mixed layer depth due to latent heat flux (LHF) anomalies. As incoming climatological solar radiation goes into a thinner (thicker) mixed layer, the shallower (deeper) mixed layer promotes surface warming (cooling). This leads to positive (negative) SST anomalies, developing the SST‐W4 pattern during austral summer. Subsequently, anomalous entrainment due to the temperature difference between the mixed layer and the water below the mixed layer, anomalous LHF, and disappearance of the overlying atmospheric W4 pattern cause the decay of the SST‐W4 pattern during austral autumn. These results indicate that accurate simulation of the atmospheric forcing and the associated atmosphere‐ocean interaction is essential to capture the SST‐W4 pattern in coupled models.

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Section: Summary and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Southern Hemisphere Circumpolar Wavenumber‐4 Pattern Simulated in SINTEX‐F2 Coupled Model

Senapati,

Morioka,

Behera

et al. 2024

JGR Oceans

Self Cite

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“…Decadal sea surface temperatures (SST) variability has been associated with decadal climate variability worldwide (Z. Liu, 2012), from the Atlantic (Kushnir, 1994; Sutton & Hodson, 2005; R. Zhang & Delworth, 2006; Msadek & Frankignoul, 2009; R. Zhang et al., 2019) to the Pacific (Y. Zhang et al., 1997; Mantua et al., 1997; Deser et al., 2004; Newman et al., 2016; Stolpe et al., 2017) and Southern Ocean (Wang & Dommenget, 2016; Latif et al., 2017; L. Zhang et al., 2017; Senapati et al., 2022). These variabilities, notably the Atlantic Multidecadal Variability (AMV) and Pacific Decadal Variability (PDV), have been suggested to exert strong climate impact regionally and globally (Goldenberg et al., 2001; R. Zhang & Delworth, 2006; Ting et al., 2009; Schubert et al., 2009; Yeager et al., 2015; O’Reilly et al., 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Zhang et al, 1997;Mantua et al, 1997;Deser et al, 2004;Newman et al, 2016;Stolpe et al, 2017) and Southern Ocean (Wang & Dommenget, 2016;Latif et al, 2017;L. Zhang et al, 2017;Senapati et al, 2022). These variabilities, notably the Atlantic Multidecadal Variability (AMV) and Pacific Decadal Variability (PDV), have been suggested to exert strong climate impact regionally and globally (Goldenberg et al, 2001;R.…”

Section: Introductionmentioning

confidence: 99%

Strong Oceanic Forcing on Decadal Surface Temperature Variability Over Global Ocean

Gu,

Liu,

Delworth

2024

Geophysical Research Letters

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Sea surface temperature (SST) variability on decadal timescales has been associated with global and regional climate variability and impacts. The mechanisms that drive decadal SST variability, however, remain highly uncertain. Many previous studies have examined the role of atmospheric variability in driving decadal SST variations. Here we assess the strength of oceanic forcing in driving decadal SST variability in observations and state‐of‐the‐art climate models by analyzing the relationship between surface heat flux and SST. We find a largely similar pattern of decadal oceanic forcing across all ocean basins, characterized by oceanic forcing about twice the strength of the atmospheric forcing in the mid‐ and high latitude regions, but comparable or weaker than the atmospheric forcing in the subtropics. The decadal oceanic forcing is hypothesized to be associated with the wind‐driven oceanic circulation, which is common across all ocean basins.

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A change in the relation between the Subtropical Indian Ocean Dipole and the South Atlantic Ocean Dipole indices in the past four decades

Zhong

Vihma

et al. 2023

Atmos. Chem. Phys.

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Abstract. We utilized the global atmospheric reanalysis ERA5 and reconstructed sea surface temperature (SST) data from 1979 through 2020 to examine the stability of the relationship between the SST oscillations in the southern Indian Ocean and the Atlantic Ocean, as described by the Subtropical Indian Ocean Dipole (SIOD) and South Atlantic Ocean Dipole (SAOD) indices, respectively. We note a significant positive correlation between the two indices prior to the year 2000 but practically no correlation afterwards. We show that in the two decades prior to 2000, a positive phase of the SAOD is associated with more convective activities over the subtropical southern Atlantic Ocean and eastern Brazil, which trigger a stronger upper-atmosphere wavetrain. This produces stronger southern subtropical highs and surface anti-cyclonic circulations and therefore a stronger correlation between the two indices. The situation is reversed after 2000. Our results are potentially applicable to predictions of precipitation in southern Africa and South America.

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Decadal Variability of Southern Subtropical SST Wavenumber‐4 Pattern and Its Impact

Cited by 3 publications

References 37 publications

Southern Hemisphere Circumpolar Wavenumber‐4 Pattern Simulated in SINTEX‐F2 Coupled Model

Southern Hemisphere Circumpolar Wavenumber‐4 Pattern Simulated in SINTEX‐F2 Coupled Model

Strong Oceanic Forcing on Decadal Surface Temperature Variability Over Global Ocean

A change in the relation between the Subtropical Indian Ocean Dipole and the South Atlantic Ocean Dipole indices in the past four decades

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