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The new CCSM, glacial inception and the importance of inertial waves

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

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The new CCSM, glacial inception and the importance of inertial waves

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

  2. 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)

  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. left: observed temperature at 2000 m bottom left: old CCSM biases below: improvement with new overflow The Overflow Parameterization 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 115.000 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

  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)‏ 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 Hypothesis

  10. 2 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).

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

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

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

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