The new CCSM, glacial inception and the importance of inertial waves Markus Jochum, NCAR recent improvements in CCSM – version 4 glacial inception and carbon cycle the equatorial hypothesis parameterizing inertial waves

The Madden-Julian Oscillation Observations CCSM4 (Subramaniam et al, 2011) Composite November-April 20-100-day OLR (color, in Wm2) and 850 hPa wind anomalies (vectors)

NINO3 SST observations old CCSM new CCSM Neale et al. 2008

Ocean Viscosity and Climate biases in sea-ice ---> concentration, CCSM3 <---change due to lower viscosity (CCSM4) Jochum et al. 2008

The Overflow Parameterization left: observed temperature at 2000 m bottom left: old CCSM biases below: improvement with new overflow Danabasoglu et al. 2009

Glacial Inception in a transient simulation with CCSM4 red: perennial snow present day green: difference in annual snow blue: perennial snow 115.000 yrs ago accumulation 115 kya (m/yr) JJ oJochum et al. 2011

time Carbon dioxide, and deuterium/hydrogen ratio from the Vostok Ice core; and global ice volume from sediment cores (inverted). (Sigman & Boyle, 2000) g 7 7

Observed Dissolved Inorganic Carbon (mmol/m3, zonal average based on GLODAP) Southern Ocean Hypothesis after early ideas of Siegenthaler & Wenk, Sarmiento & Toggweiler, and Knox & Elroy (all 1984)‏ 8 8 Southern Ocean Hypothesis after early ideas of Siegenthaler & Wenk, Sarmiento & Toggweiler, and Knox & Elroy (all 1984)‏ Observed Dissolved Inorganic Carbon (mmol/m3)‏ (zonal average, based on GLODAP)‏

The Southern Ocean Hypothesis 9 9

color: mean ocean to atmosphere carbon fluxes in control 2 10 10 color: mean ocean to atmosphere carbon fluxes in control contour lines: OP115-CONT; solid lines indicate atmospheric gain of CO in OP115.

NEW: The Equatorial Pacific Hypothesis

The energy required for mixing across isopycnals is proportional to stratification and diffusivity: E ~ k N 2 color: Pacific mean temperature difference (115kya - CONT); blue contour: mean salinity difference (115kya - CONT); green contour: mean dissolved inorganic carbon (CONT). 12 12

air-sea carbon flux difference (OP115lowdiff - OP115) 13 13

Red: 115 kya continued with reduced diapycnal diffusivity Black: 115 kya simulation Red: 115 kya continued with reduced diapycnal diffusivity 14 14

Near-Inertial Waves – the new Aspirin A climate process team together with SIO, UW, Univ. Mich. & Alaska, GFDL, FSU and WHOI Jochum, Briegleb, Danabasoglu, Bryan, Gent, Large (NCAR) & Alford (APL) A climate process team together with SIO, UW, Univ. Mich. & Alaska, GFDL, FSU and WHOI

NIW motions in CCSM4

Correlation between NI zonal velocity and its parameterization u= -T/2pi dv/dt v=T/2pi du/dt

Impact of Near-Inertial Waves on boundary layer depth

Impact of NIWs on tropical precipitation gray: SST changes red: reduced rain blue: increased rain

... and their impact on the surface wind stress

Conclusions the new CCSM4 now features realistic MJOs, ENSOs, improved sea-ice distribution and deep water properties it also reproduces the last glacial inception, so that changes in Earth's orbit are sufficient to explain glacial inception changes in diapycnal mixing appear as a key process to explain the drawdown of atmospheric carbondioxide during the ice ages near-inertial waves are a key component of the climate system, but they are still poorly observed and modelled