Climate prediction activities at Météo-France Hervé Douville Météo-France/CNRM herve.douville@meteo.fr Acknowledgements: L. Batté, C. Ardilouze, M. Déqué, J-F. Guérémy, J-P. Piedelièvre and E. Maisonnave WGSIP 16th session, Exeter,, 10-12 March 2014

Outline Sensitivity tests to resolution Towards System 5 Recent global warming hiatus Summary and prospects

Sensitivity tests to resolution Experiment design 1993-2009 hindcasts ARPEGE V5.1 AGCM / NEMO V3.2 OGCM (climatological sea-ice) Low Res: Tl127 (1.4°) L31 (or L71 for high-top) / 1°L42 High Res: Tl359 (0.5°) L31 / 0.25°L75 (with CERFACS) 4 seasons (start 1 Feb, May, Aug, Nov) till month 4 30 members (initial atmosphere perturbation) 10 members till month 7 60 members in high resolution (30 selected, sampling intervals) Atmosphere start: Era interim Ocean start: Glorys/Psi2g3

Horizontal resolution Nino 3.4 SST « spring barrier » (By courtesy of M. Déqué)

Horizontal or vertical resolution Nino 3.4 SST (+71l) (By courtesy of M. Déqué)

Horizontal resolution Impact on spatial mean temporal correlations Scores for extratropical Z500 90S-30S 30N-90N (By courtesy of M. Déqué)

T2M P Horizontal resolution Impact on spatial mean temporal correlations 90S-30S 30S-30N 30N-90N T2M 30N-90N 90S-30S 30S-30N P (By courtesy of M. Déqué)

High Res vs Low Res: summary Worse in the tropics in Spring Better in other seasons Significant differences (60 members) Summary of temporal correlations for extratropical circulation indices Low res High res High res A NAO (DJF) 0.41 0.46 (0.52 with 71l) 0.34 NAM (DJF) 0,39 0.60 (0.55 with 71l) 0.48 (By courtesy of M. Déqué)

Towards System 5 ACC DJF; IT=[-30,+30] ; NH=[+30,+90] ; SH=[-30,-90] ; N34=Niño3.4 32 years (1979-2010), 20 members among 30, (perturbed ICs): N8=Tl127l91, CMIP5 Physics, ajc, jpp (dt=1200s, SBU=290/mois ?), N16=Tl127l91, dyns, New Physics, ajc, SFX7.3, gelato, jpp (dt=900s, SBU=590/mois), N17=id N16 Tl159l91, jpp; NP_HTg159=id N17-dyns-O3 pro, jfg N8 N16 N17 NP_HTg159 T2m .IT 0.50 0.51 0.51 0.53 0.54 0.54 + 0.52 0.53 0.54 + - 0.54 0.55 0.55 + + + Z500.IT 0.63 0.64 0.65 0.67 0.68 0.69 + 0.64 0.65 0.66 + - 0.68 0.69 0.70 + + + PREC.IT 0.53 0.54 0.54 0.55 0.56 0.56 + 0.54 0.54 0.55 + - 0.50 0.50 0.50 - - - T2m .NH 0.23 0.25 0.28 0.21 0.24 0.27 = 0.21 0.24 0.27 = = 0.26 0.28 0.30 + + + Z500.NH 0.24 0.27 0.31 0.23 0.27 0.31 = 0.17 0.23 0.27 - - 0.31 0.33 0.36 + + + PREC.NH 0.13 0.14 0.15 0.12 0.15 0.17 = 0.12 0.13 0.16 - = 0.16 0.18 0.20 + + + T2m .SH 0.30 0.32 0.34 0.28 0.29 0.31 - 0.26 0.28 0.30 - = 0.30 0.32 0.33 = + + Z500.SH 0.29 0.32 0.35 0.28 0.33 0.36 = 0.30 0.33 0.37 = = 0.30 0.34 0.37 = = = PREC.SH 0.11 0.12 0.14 0.15 0.16 0.18 + 0.14 0.16 0.18 + = 0.12 0.13 0.15 = - - T2m.N34 0.93 0.93 0.93 0.94 0.94 0.94 + 0.94 0.94 0.94 + = 0.93 0.93 0.93 = - - In red, comparison vs neighbouring left column, blue (green) vs first (second) column (By courtesy of J-F. Guérémy)

Cor DJF (30 members) Towards System 5 N8 N16 N17 NP_HTg159 (By courtesy of J-F. Guérémy)

Cor DJF (30 members) Towards System 5 N8 N16 N17 NP_HTg159 (By courtesy of J-F. Guérémy)

ENSO contribution to the recent global warming hiatus Experiment design 1979-2012 integrations ARPEGE V5.2 AGCM / NEMO V3.2 OGCM (Gelato sea-ice) Tl127 (1.4°) L31 / 1°L42 5 members (initial states from historical CMIP5 simulations) HISCTL: CMIP5 simulations (ALL forcings) HISSST: HISCTL + SST anomaly nudging in central and eastern tropical Pacific (as in Kosaka and Xie 2013) HISTAU: HISCTL + prescribed wind stress in the tropical Pacific (not exactly as in England et al. 2014) All anomalies relative to the 1979-2008 climatology Question not addressed here and still a matter of debate: Should we expect more la Niña events in a warmer climate?

Correlation with observed annual mean SST 1997 Domain with SST nudging in HISSST Domain with prescribed wind stress in HISTAU 1997 (Douville and Voldoire, in preparation)

Global annual mean T2M anomalies Free OAGCM Constrained OAGCM HISSST results in line with Kosaka and Xie (2013) despite a lower (more realistic) ENSO influence on global mean temperature in CNRM-CM5: ENSO multi-decadal variability (mostly internal and not predictable by state-of-the-art OAGCMs) is sufficient to explain the recent global warming hiatus; HISTAU results in line England et al. (2014) despite a reduced domain with prescribed wind stress; global warming hiatus less pronounced than in HISSST due to a too narrow ENSO signal in Pacific SST (+ cold start). (Douville and Voldoire, in preparation)

1998-2012 annual mean T2M linear trends Correlation with ERAI pattern Stippling denotes significant trends at the 5% level (i.e. weak ensemble spread) K/decade (Douville and Voldoire, in preparation)

Recent global warming hiatus 1979-2008 (Douville and Voldoire, in preparation)

End

Stochastic dynamics: principle X(t + ∆t) = X(t) + M(X(t), t) + δX Perturbed variables : T , Ψ, Q δX : random draw every 6 hours of a coherent initial tendency error correction term from a given population {δX} derived from a 32-winter 4-member coupled model run weakly (10-day relaxation time for Ψ, 1 month for T and Q) nudged towards ERA-Interim Classification of the {δX} population according to : - actual month (« perfect sampling »): SD_OPT - current month (november to february): SD_RAND - other criteria : ongoing research ! Courtesy of L. Batté

Stochastic dynamics: results Pattern ACC of DJF Z500 (northern extratropics) Mean Pattern ACC in DJF Courtesy of L. Batté

Other sensitivity tests Additional experiments (in progress) Low res initialized by Nemovar (not shown) High res with 3 hour coupling (winter only) Tl359 with stratosphere (not shown) Tl359 coupled with Nemo 1° (in progress)

Horizontal or vertical resolution Spatial mean temporal correlations for precipitation (DJF only) 90S-30S 30S-30N 30N-90N