naclim ct1 annual meeting, trieste, 1-2/10/2013
DESCRIPTION
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013. On the predictability of the winter NAO: lagged influence of autumn Eurasian snow and Arctic sea-ice. J. García-Serrano, C. Frankignoul, G. Gastineau LOCEAN-IPSL, UPMC, Paris, France. SNOW week 1. SNOW week 2. SNOW week 3. SNOW week 4. - PowerPoint PPT PresentationTRANSCRIPT
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
On the predictability of the winter NAO:
lagged influence of autumn Eurasian snow and Arctic sea-ice
J. García-Serrano, C. Frankignoul, G. Gastineau
LOCEAN-IPSL, UPMC, Paris, France
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
Extended Maximum Covariance Analysis (EMCA)
our approach relies on capturing time-evolving predictor in covariance with the winter NAO, but
holding its spatial pattern; by means of introducing different time-lags in the MCA analysis
Polo et al. & García-Serrano et al. (2008, J.CLIM)
ERA-Interim (SD): 1979-2012
NOAA/NSIDC (SCE): 1966-2012
NOAA-CIRES 20CR (SD): 1966-2010
common period 1979-2010 (October)
SNOW week 1
SNOW week 2
SNOW week 3
SNOW week 4
SNOW week 5
SLP
(DJF)
X = ( NLAGw * nsSNOW ) x nyr
Y = nsSLP x nyr
COV = ( X * Yt ) / nyr-1
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
EMCA-SCE (oct)
scf=51.2% ruv=0.77
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
upward-propagating wave activity (stratospheric mechanism)
at 100hPa
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
transient-eddy feedback (tropospheric mechanism)
at 200hPa
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
upward-propagating wave activity
(stratospheric mechanism)
at 100hPa
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
transient-eddy feedback
(tropospheric mechanism)
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
transient-eddy feedback
(tropospheric mechanism)
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
Summary:
• Both, October Eurasian SCE and autumn (Sep-Oct-Nov) Arctic SIE expansion coefficients have a correlation of ~0.7-0.8 with winter Euro-Atlantic SLP variability.
• October Eurasian SCE leads to changes in the Siberian High, which further lead to enhanced/reduced vertical wave activity over eastern Eurasia, affecting the stratospheric polar vortex over the North Pacific sector.
• Arctic SIC triggers a wavetrain crossing Eurasia in November that (i) impacts vertical wave activity over both the North Pacific and northern European sectors, hence affecting the polar vortex; and (ii) induces transient-eddy feedback over the eastern North Atlantic basin helping to maintain and amplify the tropospheric anomaly.
• The winter NAO and EMCA-SCE (October Eurasian SCE) show significant negative correlations over the Kara-Barents Seas in autumn, i.e. SIC reduction over the eastern Arctic, in agreement with MCA-SIC patterns.
• There is a negative feedback in SIC over the eastern Arctic between autumn (negative anomalies - reduction) and winter (positive anomalies - increase), which is mediated by the NAO.
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
SIC (oct) SIC (nov)
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
Summary:
• Both, October Eurasian SCE and autumn (Sep-Oct-Nov) Arctic SIE expansion coefficients have a correlation of ~0.7-0.8 with winter Euro-Atlantic SLP variability.
• October Eurasian SCE leads to changes in the Siberian High, which further lead to enhanced/reduced vertical wave activity over eastern Eurasia, affecting the stratospheric polar vortex over the North Pacific sector.
• Arctic SIC triggers a wavetrain crossing Eurasia in November that (i) impacts vertical wave activity over both the North Pacific and northern European sectors, hence affecting the polar vortex; and (ii) induces transient-eddy feedback over the eastern North Atlantic basin helping to maintain and amplify the tropospheric anomaly.
• The winter NAO and EMCA-SCE (October Eurasian SCE) show significant negative correlations over the Kara-Barents Seas in autumn, i.e. SIC reduction over the eastern Arctic, in agreement with MCA-SIC patterns.
• There is a negative feedback in SIC over the eastern Arctic between autumn (negative anomalies - reduction) and winter (positive anomalies - increase), which is mediated by the NAO.
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
Summary:
• Both, October Eurasian SCE and autumn (Sep-Oct-Nov) Arctic SIE expansion coefficients have a correlation of ~0.7-0.8 with winter Euro-Atlantic SLP variability.
• October Eurasian SCE leads to changes in the Siberian High, which further lead to enhanced/reduced vertical wave activity over eastern Eurasia, affecting the stratospheric polar vortex over the North Pacific sector.
• Arctic SIC triggers a wavetrain crossing Eurasia in November that (i) impacts vertical wave activity over both the North Pacific and northern European sectors, hence affecting the polar vortex; and (ii) induces transient-eddy feedback over the eastern North Atlantic basin helping to maintain and amplify the tropospheric anomaly.
• The winter NAO and EMCA-SCE (October Eurasian SCE) show significant negative correlations over the Kara-Barents Seas in autumn, i.e. SIC reduction over the eastern Arctic, in agreement with MCA-SIC patterns.
• There is a negative feedback in SIC over the eastern Arctic between autumn (negative anomalies - reduction) and winter (positive anomalies - increase), which is mediated by the NAO.
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
On the predictability of the winter NAO:
lagged influence of autumn Eurasian snow and Arctic sea-ice
EXTRA SLIDES
Honda et al. (2009, GRL)
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
NACLIM CT1 annual meeting, Trieste, 1-2/10/2013
The research leading to these results has received funding from the European Union 7th Framework Programme (FP7 2007-2013), under grant agreement n.308299
NACLIM www.naclim.eu