could the north pacific oscillation be modified by the ...€¦ · chen et al. (2015, 2018); tseng...
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Could the North Pacific Oscillation Be Modified by the Initiation of East Asian Winter Monsoon?
Yu-heng Tseng1, Ruiqiang Ding2, Sen Zhao3, Yi-Chun Kuo1
1Institute of Oceanography, National Taiwan University, Taiwan2Institute of Atmospheric Physics, Chinese Academy of Sciences, China
3U. Hawaii, Manoa, USA
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Ding et al. (2015c); Ding et al. (2016)
Chen et al. (2015, 2018); Tseng et al. (2017a);SFM
Ding et al. (2015a); Tseng et al. (2017b)
Ding et al. (2015b)
New North Pacific climate paradigm
Tropical-extratropical interaction
Tropical-extratropical interaction
Ding et al. (2017a)
Ding et al. (2017b)
Hu et al. (2017a; 2017b)
Miller et al. (2017)
?
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Western North Pacific-Basin scaleCorrelation of Pacific SSTa (3-month running mean) and Jan.(1) Niño3.4 at different lags from 1948–2012
Tseng et al. (2017)Also Wang et al. (2012)
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• characterized by strong NW (NE) winds and cold temp. over the northern China (southern PAMS) region
East Asian Winter Monsoon (EAWM)
EAWMI=averaged -V120-140E,5-25N (similar to Chen et al., 2000)Shading: dSLP/dy
• SH source• Land/ocean contract
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Lag-relation between EAWMI and NPO poles(1958-2017)
The correlation is not very high except the southern tip of the south pole (southern branch of the VM)
NPO [winter(0)] VM [FMA(+1)]
El Nino [winter(+1)]
LF
SFSFM
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Lag correlation of SLPa with Nov. and Dec. EAWMI
Nov.
Dec.
Modifying the southern pole
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AGCM forcing sensitivity
Numerical experiments:CAM5, Year 2000 (control, 20 years after quasi equilibrium)SST forcing x1SST forcing x2SST forcing x(-2)
NPO magnitudes are modified
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Wave activity fluxes
Near surface
500hPa
Clear wave propagation activities
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Wave activity fluxes
200 hPa
500 hPa
Much stronger at 200 hPa
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Conclusion• NPO/VM: a important footprint of the meridional
variability through the tropic-extratropical teleconnection (precursor of ENSO/PDO)
• The initialization of EAWM (Nov.) influences the development of NPO (from the south pole specifically)
• The south pole of NPO directly connects to the VM evolution into the tropics
• Model analysis confirms the pathway modifying NPOthrough the Rossby wave propagation activies
Questions: Can the improved SLPa associated with ENSO in the CESM2 change the pathway?
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The dominant surface pattern and variability in the North Pacific-2nd mode
Covariability mode of SLP and SST anomalies from CEOF2 (1948-2012)North Pacific Oscillation (NPO)
Victoria Mode (VM) or NPGO (or PMM)
• NPO itself is a stochastic mode of variability (e.g., Rogers 1981)
• However, a portion of the NPO (southern node) is dynamically linked to the CPW variability (Di Lorenzo, 2010; Furtado et al., 2012).
Here, we will show the development of NPO can also be initialized by the EAWM
Miller et al. (2017)
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Correlation of NDJ EAWMI with several lags of GH, Ω and Tair (25˚N)
Vertical structure
Southern lobe of the NPO (180-220E)
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Verified by the Rossby Wave Ray• Dispersion relation• Perturbed wave sources in the WNP
(Zhao et al., 2015 J. Clim.;Li et al., 2015 JAS)
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Rossby wave ray tracingNear surface mid-troposphere
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Rossby wave ray tracing250 hPa mid-troposphere
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Conclusion• NPO/VM: a important footprint of the meridional
variability through the tropic-extratropical teleconnection (precursor of ENSO/PDO)
• The initialization of EAWM (Nov.) influences the development of NPO (from the south pole specifically)
• The south pole of NPO directly connects to the VM evolution into the tropics
• The vertical structure is also consistent with the Rossbywave ray trajectories
• Model analysis confirms the modification of NPO, further ensemble experiments and wave-activity flux analysis will be done