Millenium simulations at IPSL THOR: C. Frankignoul, G. Gastineau, C. Marini, J. Mignot Escarsel: M. Khodri, J. Servonnat, P. Yiou THOR CT1 meeting, Bergen, Oct

The IPSL-CM4 coupled model LMDZ: atmospheric physics and dynamics horizontal resolution 96x72, 19 vertical layers OPA: ocean dynamics based on a 2 degrees Mercator mesh (orca), 31 vertical levels LIM: sea-ice dynamics and thermodynamics ORCHIDEE: land surface OASIS Marti et al

The IPSL-CM4 coupled model Simulations: - CTRL1000 years control simulation, preindustrial GHGs and tropospheric aerosols concentrations - SOL 950 years ( ) years simulation including solar forcing, historical GHGs (Joos et al. 2008) and preindustrial tropospheric aerosols concentrations - SOLVOL 300 years (starting yr 850) simulation including solar +volcanic forcing

TSI Crowley (2000), W/m -2 (a) The solar forcing Calendar time SOL SOLVOLKrivova, pers. com Amman et al. 2007: -0.25% TSI at the Maunder minimum More recent estimates: -0.1 % at the Maunder minimum

SOL – northern hemisphere temperatures Reconstructions overlap Osborn and Briffa, IPCC AR4, Solomon et al Good global agreement, Cold « bias » (Missing volcanoes, which would have decreased the warming between ) Correlation with TSI: 0.74 Servonnat et al., in prep.

Northern Hemisphere surface temperature anomalies (°C ref ) Preind. CTRL Mann et al 2008 EIV Moberg et al 2005 Crowley & Lowery 2000 Ammann & Wahl 2007 (a) (e) (d) (c) (b) SOL – northern hemisphere temperatures Comparison with four individual reconstructions Servonnat et al., in prep.

SOL – regression of temperature on TSI annual mean Max sensitivity with 15 yrs lag: 0.109°C/W.m -2 sensitivity over sea ice > over land > over ocean Servonnat et al., in prep. Lag 15 yrs

CTRL/SOL surface temperature variability CTRL SOL 80°N 40°N Eq 40°S 80°S 100°W 100°E0° 100°W 100°E0° 100°W 100°E0° 100°W 100°E0° 100°W 100°E0° 100°W 100°E0° 80°N 40°N Eq 40°S 80°S Cold period ( AD) Warm Period ( AD) - 1 SD + 1 SD Annual mean Summer Winter (a) (b) (c) (d) (e) (f) (k) (l) (i) (j)(h) 80°N 40°N Eq 40°S 80°S 80°N 40°N Eq 40°S 80°S Servonnat et al., in prep.

CTRL/SOL surface temperature variability CTRL SOL 80°N 40°N Eq 40°S 80°S 100°W 100°E0° 100°W 100°E0° 100°W 100°E0° 100°W 100°E0° 100°W 100°E0° 100°W 100°E0° 80°N 40°N Eq 40°S 80°S Cold period ( AD) Warm Period ( AD) - 1 SD + 1 SD Annual mean Summer Winter (a) (b) (c) (d) (e) (f) (k) (l) (i) (j)(h) 80°N 40°N Eq 40°S 80°S 80°N 40°N Eq 40°S 80°S Servonnat et al., in prep. Global Land Ocean = 75% = 78% = 73% Global Land Ocean = 71% = 73% = 71% Global Land Ocean = 76% = 83% = 73% Global Land Ocean = 73% = 80% = 70% Global Land Ocean = 67% = 57% = 72% Global Land Ocean = 70% CP WP Annual mean SummerWinter -1SD/+1SD SOL

SOLVOL – sensitivity of the atmospheric model to volcanic forcing b) Observations (Robock, 2000) Anomalous response of LMDZ to Mt Pinatubo eruption (DJF ) Temperature in the low troposphere 500mb geopotential a) LMDZ Khodri, pers. com.

SOLVOL – volcanic forcing in the IPSL model Sulfate aerosol in the stratosphere Volcanic eruption with a VEI>4 Essentially tropical eruptions Optic thickness of the volcanic aerosols for the Mt Pinatubo eruptions ( ) months latitude altitude DJF Mie code to compute the simple diffusion albedo and asymetry factor for the sulfate stratospheric aerosol in water phase Implementation of the optic thickness on the 2 layers above the tropopause Khodri, pers. com.

Atlantic thermohaline circulation CTRL SOL SOLVOL

Atlantic thermohaline circulation MSF average CTRL SOL SOLVOL

North Atlantic deep convection Maximum mixed layer depth in March CTRL

Barotropic streamfunction CTRL

Horizontal circulation in the North Atlantic CTRL

Horizontal circulation in the North Atlantic in winter CTRL

Horizontal circulation in the northern North Atlantic CTRL

Horizontal circulation in the northern North Atlantic in winter CTRL

Plans Use of IPSL_CM5 model: ORCA2 x LMDZ (96x95x39) run should start before end 2009 Only SOLVOL experiment? forcings? - THC variability on decadal to centennial timescale – process studies -Ocean-atmosphere feedback - internal vs externally forced variability

Implémentation de l’impact radiatif des aérosols volcanique dans MDZ  Code de Mie: Calcul de l’albédo de simple diffusion (cg) et le facteur d’asymétrie (piz) pour les aérosols stratosphériques sulfatés en phase aqueuse (forme binaire H2SOA/H2O: 75%/25%) El Chichon + Pinatubo (SO4 droplet): # R : rayon modal en nm : # Sigma : largeur de distribution: 1.30 # w1 w2 : albedo de simple diffusion sur les 2 bandes du visible : # g1 g2 : paramËtre d'assymÈtrie sur les 2 bandes du visible :  Implémentation de l’épaisseur optique (Tau) sur les 2 couches atmosphériques au dessus de la tropopause Epaisseur optique des aérosols volcanique Pour l’éruption du Mt Pinatubo ( ) mois latitude altitude DJF Khodri, pers. com.

Volcanic Explosive Index, VEI (Newhall y Self, 1982) VEI HAUTEUR DU PANACHE VOLUME D’ÉJECTION CLASSIFICATION EXEMPLE 0 <100 m 1000s m 3 Hawaiano Kilauea m 10000s m 3 Hawaiano/Estrombolia no Stromboli km s m 3 Estromboliano/Vulcani ano Galeras (1992) km m 3 VulcanianoRuiz (1985) km s m 3 Vulcaniano/Plineano Galunggung (1982) 5 >25 km 1 km 3 PlineanoSt. Helens (1980) 6 >25 km 10s km 3 Plineano/Ultra-Plineano Krakatau (1883) 7 >25 km 100s km 3 Ultra-Plineano Tambora (1815) 8 >25 km 1000s km 3 Ultra-Plineano Toba (74 ka) Volcanic eruptions with stratospheric impact : VEI > 4 Khodri, pers. com.

Mixed layer depth in the North Atlantic Monthly mean maximum Standard deviation of the March monthly values De Boyer Montégut et al. 2005

Annual mean Atlantic meridional overturning circulation Time series of the AMOC maximum

Temporal characteristics of the maximum of the annual mean AMOC

Leading mode of SLP variability over the North Atlantic

2nd EOF of SLP over the North Atlantic

Atlantic annual mean SST and SSS Reynolds Reverdin

ENSO in IPSL-CM4 First EOF of tropical Pacific SST Regression of the SLP on the corresponding principal component 64%

ENSO Model Observations (Reynolds and NCEP) 65,5 % 64 %