1. 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

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

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

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

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

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

7. 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

8. 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)‏

9. The Southern Ocean Hypothesis9 9

10. 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.

11. NEW:
The Equatorial Pacific Hypothesis

12. 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

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

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

15. 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

16. NIW motions in CCSM4

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

18. Impact of Near-Inertial Waves on boundary layer depth

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

20. ... and their impact on the surface wind stress

21. 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