Recent Acceleration of Arabian Sea Warming Induced by the Atlantic‐Western Pacific Trans‐basin Multidecadal Variability

Sun, Cheng; Li, Jianping; Kucharski, Fred; Kang, In‐Sik; Jin, Fei‐Fei; Wang, Kaicun; Wang, Chunzai; Ding, Ruiqiang; Xie, Fei

doi:10.1029/2018gl081175

Cited by 67 publications

(26 citation statements)

References 56 publications

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“…The SST cooling trend over the tropical central‐eastern Pacific largely projects on the negative IPO phase, and it is known that the IPO shifted from a positive phase to a negative phase in the late 1990s (Dong and McPhaden, 2017). In addition, due to the effects of trans‐basin atmospheric teleconnections and coupled air‐sea interaction, the tropical SST trend dipole can be linked to the Atlantic multidecadal variability (Li et al, ; McGregor et al, ; Sun et al, ; Sun, Li, Kucharski, Kang, et al, ), which is to a large extent a result of internal climate variability and induced by the ocean circulation variations (i.e., Atlantic meridional overturning circulation; Sun et al, ; Sun, Li, Kucharski, Xue, & Li, ; Zhang et al, ). Besides the Atlantic Ocean, the Indian Ocean warming in recent decades may also have an effect in shaping the tropical SST trend dipole pattern, leading to a cooling trend over the tropical eastern Pacific region (Luo et al, ; Lee et al, ; Nieves et al, ; Dong & McPhaden, ).…”

Section: Resultsmentioning

confidence: 99%

Spring Aleutian Low Weakening and Surface Cooling Trend in Northwest North America During Recent Decades

Sun

Kucharski

et al. 2019

JGR Atmospheres

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State‐of‐the‐art climate models predict an enhanced warming over global land areas in response to the greenhouse gas (GHG) forcing. In nature, however, the observed land surface warming is not spatially uniform in recent decades as GHG concentration has risen rapidly. There is no warming and even cooling trend in spring northwest North America (NWNA) surface temperature since 1980. Here, we link the observed multidecadal surface cooling trend in NWNA to the weakening of spring Aleutian low (AL), which is ecologically important during the growing season. The AL weakening leads to reductions of southwesterly wind and warm air transport from eastern North Pacific to NWNA. The spring AL weakening and associated NWNA surface cooling are reasonably reproduced by AMIP models, driven by the historical external forcing and imposed sea ice concentration (SIC) and sea surface temperature (SST) from observations. Further investigations into the roles of different forcing components suggest that the changes in the AL are most likely driven by the tropical SST changes in recent decades while the external forcing and SIC play minor roles. There is a zonal dipole pattern of trends in tropical SSTs since 1980, with central‐eastern Pacific cooling and warming in other tropical basins, and the atmospheric responses to this SST change show a meridionally propagating Rossby wave train from tropics into subarctic North Pacific, which mediates the SST forcing and the AL changes.

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Section: Resultsmentioning

confidence: 99%

Spring Aleutian Low Weakening and Surface Cooling Trend in Northwest North America During Recent Decades

Sun

Kucharski

et al. 2019

JGR Atmospheres

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“…Similarly, the potential impacts of changes to SST on the WTV also need further examination. For example, we know that the Eurasian atmospheric circulation is not only influenced by Atlantic SST variability (Sun et al 2015(Sun et al , 2017a, but also by SST variability over the surrounding Indian Ocean and western tropical Pacific (Sun et al 2017b(Sun et al , 2019. This SST variability could play an important role in the formation and development of the internal dynamics associated with the WTV.…”

Section: Discussionmentioning

confidence: 99%

Thermodynamic controls of the Western Tibetan Vortex on Tibetan air temperature

Fowler

et al. 2019

Clim Dyn

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The "Western Tibetan Vortex" (WTV)-also termed the Karakoram Vortex-dominates the middle-to-lower troposphere and the near-surface air temperature variability above the western Tibetan Plateau (TP). Here, we explore the thermodynamic mechanisms through which the WTV modulates air temperature over the western TP by diagnosing the three major terms of the thermodynamic energy equation-adiabatic heating, horizontal temperature advection, and diabatic heating-that maintain the atmospheric thermal balance. We composite these major terms to examine the differences between anti-cyclonic and cyclonic WTV events. Our theoretical approach demonstrates that adiabatic sinking-compression (rising-expansion) provides the overwhelming control on both the middle-to-lower tropospheric and lower stratospheric temperature increases (decreases) under anti-cyclonic (cyclonic) WTV conditions over the western TP high mountain area in all four seasons. This also explains the mechanisms behind the anomalous temperature "dipole" found between the mid-lower troposphere and lower stratosphere when the WTV was initially identified. Spatially, adiabatic heating effects are centred on the central western TP in summer and the south slope centring at 70°-80°E of the TP in other seasons. The other two terms, horizontal temperature advection and diabatic heating, have localized importance over the edges of the western TP. In a case study over the Karakoram area, we further demonstrate that adiabatic heating (rising-expanding-cooling/sinking-compressing-warming) is the dominant thermodynamic process controlling Karakoram air temperatures under WTV variability, except for at the very near surface in autumn and winter. Our analysis methods can be applied to investigate the thermodynamic processes of other atmospheric circulation systems or climate variability modes.

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“…As an intermediate‐complexity numerical model, the SPEEDY AGCM is widely used in climate research and can help to understand and verify atmospheric responses to specific forcings (e.g., Kosovelj et al, 2019; Kucharski & Molteni, 2003; Kucharski, Molteni, & Yoo, 2006; Nnamchi et al, 2013). The SPEEDY AGCM has been widely used in studies related to NA SST‐associated atmospheric changes (e.g., Herceg‐Bulić & Kucharski, 2014; Kucharski et al, 2016; Kucharski & Molteni, 2003; Nnamchi et al, 2013; Sun et al, 2019). In this study, we use the SPEEDY AGCM to verify that the SST over the North Atlantic Ocean can excite a wave train propagating downstream to the TP after the mid‐1990s.…”

Section: Data Methods and Numerical Modelmentioning

confidence: 99%

On the Interdecadal Change in the Interannual Variation in Autumn Snow Cover Over the Central Eastern Tibetan Plateau in the Mid‐1990s

Qian

Xiao-ming

2020

JGR Atmospheres

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The interdecadal changes in the mechanisms accounting for the interannual variation in autumn snow cover over the central eastern Tibetan Plateau (TP) are investigated in this study. An autumn snow index is constructed by area averaging the snow cover over the central eastern TP. The snow index changed from a predominantly negative phase to a positive phase in 1995. Then, the data were divided into two subperiods, 1979–1994 (P1) and 1995–2017 (P2), and the differences in the mechanisms accounting for the variation in autumn snow cover were compared between P1 and P2. An analysis of the local process shows that the autumn snow cover variations over the central eastern TP are caused by snowfall from both autumn and late summer. The autumn snow cover variation over the central eastern TP imposed more significant atmospheric cooling effects during P1 than P2. During P2, except for the local process, the interannual variation in autumn snow cover in the central eastern TP is also affected by atmospheric circulation anomalies originating from the upstream North Atlantic Ocean. During P2, snow‐related North Atlantic sea surface temperature (SST) anomalies (SSTA) can induce a wave train‐like atmospheric pattern that propagates eastward across the Eurasian continent and reaches the TP. Further analysis shows that this wave train‐like atmospheric pattern over the midlatitude Eurasian continent mainly obtains energy from climatological mean flow through baroclinic energy conversion. In contrast, during P1, the North Atlantic SSTA‐related atmospheric circulation pattern tends to propagate northeastward and cannot contribute to the variation in autumn snow cover over the central eastern TP.

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Recent Acceleration of Arabian Sea Warming Induced by the Atlantic‐Western Pacific Trans‐basin Multidecadal Variability

Cited by 67 publications

References 56 publications

Spring Aleutian Low Weakening and Surface Cooling Trend in Northwest North America During Recent Decades

Spring Aleutian Low Weakening and Surface Cooling Trend in Northwest North America During Recent Decades

Thermodynamic controls of the Western Tibetan Vortex on Tibetan air temperature

On the Interdecadal Change in the Interannual Variation in Autumn Snow Cover Over the Central Eastern Tibetan Plateau in the Mid‐1990s

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