Thierry Penduff CNRS, LEGI, France, & Dpt Oceanogr., FSU, USA. IFM-GEOMAR Germany NOCS UK Univ. Reading UK SIO Russia Univ.

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1 DRAKKAR Barnier et al, 2006 Penduff et al, 2006 DRAKKAR Group, 2007 LEGI France LPO France LOCEAN France Mercator France LSCE France Thierry Penduff CNRS, LEGI, France, & Dpt Oceanogr., FSU, USA IFM-GEOMAR Germany NOCS UK Univ. Reading UK SIO Russia Univ. Alberta Canada 50-yr forced ocean/sea-ice simulation ensembles NEMO (OPA9 ocean, LIM2/3 sea-ice, TOP tracer ( 14 C, CFC 11 ) AGRIF grid refinement software (Debreu et al 2008) + Bernard Barnier Anne-Marie Treguier Gurvan Madec Julie Deshayes Julien Le Sommer Claus Böning Arne Biastoch Gilles Garric Adrian New Sergey Gulev James Orr Keith Haines Paul Myers Jean-Marc Molines The DRAKKAR project : objectives, models, simulations, numerics From 2 to 1/4 resolution : mean currents, interannual variability Interannual variability at 1/4 : partly intrinsic

2 DRAKKAR objectives Barnier et al, 2006 Penduff et al, 2006 DRAKKAR Group, 2007 Develop and improve a hierarchy of ocean/sea-ice model configurations Build and distribute a coordinated ensemble of numerical simulations Study variability processes in collaboration Global : 2 1/4 1/12 Regional : 1/4 1/12 1/36 Grid refinement tools Collab. with Mercator + HYCOM Period : last 50 years Continuous calibration of forcing Shared simulation database Assessment metrics Eddies, scale interactions Subpolar Atlantic Southern Ocean Strong link with obs.

3 DRAKKAR configurations (global & 2-way AGRIF) 1/24 1/20 Chanut et al, 2008 Jouanno et al, Biastoch et al, /32 % Nested Stand-alone Global sea level (m) 䇱 &% '% 1/24

4 Ensemble of simulations Advection Schemes 3D or surface Relaxation Global, NATL Global 1/12 Other 1/10 1/4 1/2 1 2 Forcing

5 Numerics: Moment. adv. scheme + partial steps (1/4 ) ()*+,%% +-./012%343%, :6% Barnier et al, 2006 Penduff et al, 2007 Le Sommer et al, :2.HEF2:6B.9CDEF19:62.7G:H% 3:6B.9CDEF19:62.7G:H% I9I2:B-I%0J72189:%61D2I2%K(.0R0S0% I9I2:B-I%0J72189:%61D2I2% T%<0I5%LUN%O%C0.80P%6B2C6%B9C9HQ% K+0J9-.:E%LMN%O%/-PP%6B2C6% B9C9HQ% Less bottom friction% Enhanced eddy-topo interactions Stronger topostrophy Improved solutions

6 Impact of resolution on mean currents current meter records (Holloway, 2008) Mean DRAKKAR velocities collocated on CM Skills : Holloway and Sou (1996) MODEL OBS DIFFERENCE MKE misfit (cm 2 /s 2 ) 0% -60% Penduff et al, in prep Global Models 2 1/2 1/4 Model-CM agreement on current orientations % 0% Increasing resolution: Magnitudes & orientations towards CM Topographic rectification currents along along Topog RW Agreement on Topostrophy: mean(u model.u topo )% % F% V%SGBD% 3W+ OX6B2C6%

7 Impact of resolution on interann. variab (zonal averages) 87'%-9'((7'5 :+%/%1'5+ 6(&+*'((7' )3+::9+* 89+)3+::9+* %&' & ()*+,&-./,01-89+)3+::9+* 3:;76::9+* 89+)3+::9+* 89+)3+::9+* :;76::9+*/,*)- 87'%-9'((7'5 '*;+9%1'5+ -(&+*'((7'5 (L6 only) % 6(&+*'((7'5 / %&' & ()*+,&-./,01- / BC BC B B B B 0DE & ()*+ 1D' F)*+ DG%./ B B Penduff et al, 2009 %&'()'*))+,-'./(%0123 BC &+24/*'51/**+5'./(% BC%4'.'51/**+5'./(% %&' ()*+,&-./,01-0DE ()*+ 1D' F)*+ DG%./ 0DE (%&')*+ 1D' F%&')*+ DG%./ & & HFI A () '() m () / / B BC B B B BC B BC B 0DE & ()*+ 1D' F)*+ DG%./ C t m () BC BC B BC BC B B B B 0DE HFI (%&')*+ 1D' F%&')*+ DG%./ 0DE HFI (%&')*+ 1D' F%&')*+ DG%./ BC BC B B B B B B B B B B BC BC // B B / B B 47J5 B BC BC BC B B 0DE & ()*+ 1D' F)*+ DG%./ B B B BC B B B C s m () BC B B 0DE HFI (%&')*+ 1D' F%&')*+ DG%./ %&' & ()*+,&-./,01- - */,*)- / / / BC BC

8 Interannual variability : SLA with & without interannual forcing (global 1/4 ) Seasonal Forcing %&' (x,y,t) collocation of model SLAs onto AVISO maps % (%&' OBS Interann Forcing )* Std dev. of interannual SLA (cm) I-1/4 int. forcing 1/2, 1, 2 S-1/4 latitude%

9 Interannual variability : AMOC with/without Agulhas eddies Biastoch et al Nature 2008 & 2009 '% YP950P%&% Southern, turbulent origin of interannual AMOC variability AMOC anomalies due to Agulhas mesoscale AGULHAS

10 Planned work for %X,;*WY % % %3(FG:B2.GI%10PG5.089:270P-089:Q%W2S%60B2PPGB2%C.9J-1B6Q%3:6-.2%19:8:-GBE% % % %&'\]Q%X9^%42IC2.%KOW2CB-:2_N%0B%P9S2.%.26Q%<G:R%SGBD%5G9H291DGIG6B6% % %(Y*X%J272P9CI2:B%O%.20PG681%GICP2I2:B089:6%KY-G:20%[06G:b%972.c9S6N% % % %3P06B9F7G619FCP0681%.D29P9HE%K19:8:-2%B26B6%0B%&N%% %=,+a%=,;3++*wy % %+a,(y3%(a%?g%26 % %+B.0B2HG26%/9.%J0B0%19IC.266G9:b%IG:GI0P%P966%9/%G:/9.I089:Q%