1. WP3: Linkages of Arctic climate changes to lower latitudes
EU H2020 Blue-Action
WP3: Linkages of Arctic climate changes to lower latitudes
Yongqi Gao, Guillaume Gastineau and WP3 Partners

2. Arctic Warming Kug et al. 2015
Figure 1 | SAT trends and Arctic temperature (ART) indices. a,b, The linear trend in surface air temperature during December–February for the periods 1979/1980–1997/1998 (a) and 1997/1998–2013/2014 (b) from the observed DATA. Arctic warming (winter) has decadal variations.
Kug et al. 2015

3. AMO ( )

4. PDO ( )

5. Objective
To investigate the Arctic warming impact and its modulation by the Atlantic Multidecadal Oscillation (AMO) and Interdecadel Pacific Oscillation (IPO) on the Arctic warming impact since 1979 by using specifically-designed coordinated multi-model experiments (both Atmosphere General Circulation Models and Coupled Climate Models)

6. Coordinated AGCM Experiments (T3.1)
External forcing: CMIP6
Boundary forcing: Daily SIC and SST from HadISST (
Ensemble size:minimum 5 members for high resolution models or 20 members for standard resolution.

7. Coordinated AGCM Experiments (T3.1)
Exp1: Daily SIC and SST from 1979 to present
Exp2: daily SIC climatology in Arctic or Northern Hemisphere (mean of 1979 to present) and daily-varying SST from 1979 to present
Arctic warming impact =Exp1 minus Exp2

8. Coordinated AGCM Experiments (T3.1)
Exp3: daily-varying SIC from 1979 to present and time- varied daily SST (1979 to present) with PDO signal removed in Pacific (25oS-60oN) (25oS-Bering Strait) (Transition zone: 35oS to 25oS in Pacific sector)
Impact of PDO =Exp1-Exp3 
Exp4: daily-varying SIC from 1979 to present and time- varied daily SST (1979 to present) with AMO signal removed in North Atlantic (0-60oN) (tropical-Greenland- Iceland-Scotland Ridge) )(Transition zone: 10oS-0 in Atlantic sector)
Impact of AMO=Exp1-Exp4

9. Coordinated AGCM Experiments (T3.1)
Boundary Forcing is available for Exp.3 and Exp.4

10. Jennifer Mecking1, Sybren Drijfhout1, Malcolm Roberts2
Atmosphere model setup:
Unified Model (UM), GA7.1
N216, approx. ½° latitude by ¾° longitude
SST
SIC
# ensemble members
Exp1
Inter-annual 10
Exp2
mean
Exp2 early
mean 5
Exp2 late
mean
Exp3
Inter-annual no PDV
5 computing
Exp4
Inter-annual no AMV
Jennifer Mecking1, Sybren Drijfhout1, Malcolm Roberts2
1 University of Southampton at National Oceanography Centre, Southampton UK
2UK Met Office, Exeter UK

11. EC-Earth AMIP & Reanalysis
Mean AMET of the entire series from 20N to 90N of EC-Earth, compared with the results from reanalysis products (see WP2).
Yang, Ronald, Gijs, Jisk & Wilco from Netherlands eScience Center

12. Coordinated AOGCM Experiments (T3.2)
Constrain/nudge the Arctic sea ice concentration, the Pacific and the Atlantic SST in AOGCM
Sea surface temperature; albedo; surface heat flux; model bias

13. Suo et al. 2017, Environ. Res. Lett.
Sea Ice Free Arctic Slows Down the Projected Warming over the North Atlantic
Suo et al. 2017, Environ. Res. Lett.

14. Experimental Design

15. Annual SAT Changes

16. Conclusions
Sea-Ice free Arctic contributes to the projected NA warming minimum by weakening the AMOC.
The weakened AMOC is sustained by the weakened wind stress and by a freshening of the ocean surface layer in the sub-polar North Atlantic Ocean.

17. IPSL+CNRS-EPOC (Juliette Mignot & Didier Swingedouw) contributions to WP3
T3.3 Impact of Arctic Ocean freshening on Northern Hemisphere climate:
IPSL-CM6 still not frozen
We plan to run IPSL-CM6 model with surface nudging and including FW input for the period We plan also to make historical simulation with such a freshwater input for detection-attribution purpose
We want to understand pathways of freshwater release around Greenland by the use of passive tracers
Two postdocs will arrive this spring:
Marion Devilliers will help to develop freshwater release based on new estimate provided by Jonathan Bamber (agreement from him on this aspect) and Jason Box (data received)
Mohamed Ayache, expert in passive tracers, will do passive tracer simulations using IPSL-CM6 (1°) and also GLORYS reanalysis (1/4°)

18. Coordinated AGCM Experiments (T3.4)
Repeat T3.1 with improved scheme for surface heat flux

19. WP3 Talks Richard Davy (NERSC): Measuring Arctic amplification
Jennifer Mecking (UoS): The Simulated Atmospheric Response to Changes in Sea Ice Extent