Pacific Influences on Tropical Atlantic Teleconnections to the Southern Hemisphere High Latitudes

Simpkins, Graham; Peings, Yannick; Magnúsdóttir, Guðrún

doi:10.1175/jcli-d-15-0645.1

Cited by 34 publications

(25 citation statements)

References 64 publications

(103 reference statements)

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“…2b and 2e. In the North Atlantic, the signal resembles the negative NAO [consistent with WACCM experiments from Peings and Magnusdottir (2016)]. In the North Pacific, the response opposes the effect of 1IPV.…”

Section: A the Large-scale Midtropospheric Responsesupporting

confidence: 75%

“…For example, they have been linked with multidecadal fluctuations in tropical cyclone activity (e.g., Vimont and Kossin 2007), Sahel monsoon rainfall (Wang et al 2012) and temperature/precipitation over North America and Europe (Enfield et al 2001;Sutton and Hodson 2005). The AMV has also been shown to be associated with long-term trends in the North Atlantic Oscillation (NAO; Hurrell and van Loon 1997), and the AMV has been suggested as a driver of multidecadal variability in North Atlantic weather regimes and associated extreme weather over Europe (Peings and Magnusdottir 2014;Omrani et al 2014;Peings and Magnusdottir 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, with an AMV phase shift predicted to be looming (Frajka-Williams et al 2017), the atmospheric response to a positive IPV forcing alone must be investigated further. Exploring the combined influence of AMV and IPV is particularly useful to anticipate decadal shifts in jet/storm track variability and associated extreme weather events in the Northern Hemisphere (Peings and Magnusdottir 2016).…”

Section: Introductionmentioning

confidence: 99%

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The Atmospheric Response to Positive IPV, Positive AMV, and Their Combination in Boreal Winter

et al. 2019

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The interdecadal Pacific oscillation (hereafter termed IPV, using “variability” in lieu of “oscillation”) and the Atlantic multidecadal oscillation (hereafter AMV, similar to IPV) are regulators of global mean temperature, large-scale atmospheric circulation, regional temperature and precipitation, and related extreme events. Despite a growing recognition of their importance, the combined influence of these modes of low-frequency sea surface temperature (SST) variability remains elusive given the short instrumental record and the difficulty of coupled climate models to simulate them satisfactorily. In this study, idealized simulations with two atmospheric global climate models (AGCMs) are used to show a partial cancellation of the North Pacific atmospheric response to positive IPV (i.e., deeper Aleutian low) by the concurrent positive phase of the AMV. This effect arises from a modulation of the interbasin Walker circulation that weakens deep convection in the western Pacific and the associated Rossby wave train into the northern extratropics. The weaker Aleutian low response is associated with less upward wave activity flux in the North Pacific; however, the associated stratospheric jet weakening is similar to when the +IPV alone forces the vortex, as additional upward wave activity flux over Siberia makes up the difference. While comparable warming of the polar stratosphere is found when the positive AMV is included with the positive IPV, the downward propagation of the stratospheric response is significantly reduced, which has implications for the associated surface temperature extremes. The robust anticorrelation between the positive IPV and positive AMV signals over the North Pacific and their lack of additivity highlight the need to consider the IPV–AMV interplay for anticipating decadal changes in mean climate and extreme events in the Northern Hemisphere.

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Section: A the Large-scale Midtropospheric Responsesupporting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Atmospheric Response to Positive IPV, Positive AMV, and Their Combination in Boreal Winter

et al. 2019

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“…We use the default settings of CAM5.3. The default simulation can well simulate the SST‐induced wind and precipitation variations (e.g., Lyu et al, 2017; Simpkins et al, 2016; Wang et al, 2007; Zhou & Khairoutdinov, 2017; Zuo et al, 2018). The details of the physical parameterizations were described in Neale et al (2012).…”

Section: Data and Numerical Experimentsmentioning

confidence: 99%

The Impact of SST on the Zonal Variability of the Western Pacific Subtropical High in Boreal Summer

Wang

2020

JGR Atmospheres

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Summertime western Pacific subtropical high (WPSH) is closely related to remote sea surface temperature anomalies (SSTA) in the tropical oceans (TO) and local SSTA in the western North Pacific (WNP). Based on atmospheric reanalysis and multimodel ensemble products, the warming (cooling) of the tropical Indian, tropical central‐eastern Pacific, and tropical Atlantic (tropical western Pacific and WNP) can lead to westward extension of the WPSH, and vice versa. A series of numerical experiments are conducted to quantify the relative importance of remote and local SSTA, including the separate impact of different TO basins. In response to warming (cooling) of the tropical Indian, tropical central‐eastern (western) Pacific, and tropical Atlantic, ascending (descending) motions develop locally and subsequently excite remote baroclinic and barotropic responses. The baroclinic anticyclone west of 140°E contributes to the westward extension of the WPSH. The barotropic anticyclone and descending motion over the WNP can further increase the sea level pressure and strengthen the WPSH. Based on the quasi‐geostrophic omega equation, we find that the anomalous vorticity advection (thermal advection) primarily accounts for the anomalous descending motion in response to remote (local) SSTA. Compared to local SSTA, the remote SSTA can induce larger perturbations, subsequently making the zonal variability of the WPSH more significant. Furthermore, it is found that the westward extension of the WPSH is primarily induced by atmospheric baroclinic (barotropic) response to the SSTA in tropical Indian and tropical Atlantic (tropical Pacific). Overall, the tropical Indian plays the most important role on the zonal movement of the WPSH.

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“…Following Zebiak (1993), the ATL3 index was calculated as the SST anomaly in a region located in the central-eastern tropical Atlantic (3 S-3 N, 20 W-0 E). Positive values refer to Atlantic Niño conditions (Graham et al, 2016). A spatial extension of this region covers the cold tongue area (Lübbecke and McPhaden, 2013), which suggests a difference between Atlantic Niño and ACT.…”

Section: Data and Numerical Experimentsmentioning

confidence: 99%

Sensitivity studies of the RegCM4 simulation in West and central Africa during strong and weak years of Atlantic cold tongue

Kenfack

Mkankam

Alory

et al. 2018

Intl Journal of Climatology

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This study evaluates the ability of the Regional Climate Model (RegCM4) to reproduce the observed rainfall and wind over West and central Africa (WCA) during two contrasting years of the Atlantic cold tongue (ACT): the very cold in 1992 and very warm in 2007 depicted by the Caniaux et al.’s index. The convective schemes of Kuo, Massachusetts Institute of Technology‐Emanuel (Ema) and Grell with closure assumptions of Arakawa–Schubert (GAS) and Fritch–Chappel (GFC) were compared and the best scheme was tested to study the sensitivity of WCA climate to ACT in August of each chosen year—the month which follows that of the peak of ACT. Comparisons of simulations for 1992 and 2007 reveal that some areas are sensitive to extreme ACT events. The regional distribution of observed precipitation (wind) in August 2007 was heavier (lower intensity) than that for the 1992, particularly in West than central Africa region. From GPCP data, it is observed that the range of Cameroon highlands and the Bauchi Plateau of Nigeria are not significantly affected by the ACT. It is shown that rainfall of some subregions is very sensitive to ACT. The GFC scheme is capable of reproducing the amount and distribution of the precipitation for the 2 years in the ACT area, the west and east Guinean coasts, and failed to reproduce the rainfall in west and central Soudano–Sahel regions and East Africa. However, the Kuo scheme reproduces well in these three zones. Contrarily to rainfall, the Ema scheme better reproduces, but overestimating, the wind distribution in the Sahara region. GFC better simulates the wind speed sensitivity to ACT far from the coast in Soudano–Sahel and Nigeria–Cameroon zones. The GAS and Kuo are not well correlated with ERA‐Interim in WCA. Most of the schemes adequately mimic the African easterly jet structure.

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Pacific Influences on Tropical Atlantic Teleconnections to the Southern Hemisphere High Latitudes

Cited by 34 publications

References 64 publications

The Atmospheric Response to Positive IPV, Positive AMV, and Their Combination in Boreal Winter

The Atmospheric Response to Positive IPV, Positive AMV, and Their Combination in Boreal Winter

The Impact of SST on the Zonal Variability of the Western Pacific Subtropical High in Boreal Summer

Sensitivity studies of the RegCM4 simulation in West and central Africa during strong and weak years of Atlantic cold tongue

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