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Activity of K-1 Japan in APE

Activity of K-1 Japan in APE. Masahiro Watanabe ( Hokkaido University ) and Masahide Kimoto ( CCSR, University of Tokyo ) leading The K-1 Japan project team: Center for Climate System Research (CCSR) National Institute for Environmental Studies (NIES)

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Activity of K-1 Japan in APE

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  1. Activity of K-1 Japan in APE Masahiro Watanabe (Hokkaido University) and Masahide Kimoto (CCSR, University of Tokyo) leading The K-1 Japan project team: Center for Climate System Research (CCSR) National Institute for Environmental Studies (NIES) Frontier Research Center for Global Change (FRCGC) hiro@ees.hokudai.ac.jp

  2. K-1 Japan: CCSR/NIES/FRCGC AGCM ver. 5.7 • Same atmospheric model as used for IPCC FAR • Dynamics • T42 spectral representation • Vertical 20 s layers • Semi-Lagrangian moisture / cloud water transports (Lin & Rood 1996) • Physics: • Prognostic Arakawa-Schubert (Pan and Randall, 1998) • Prognostic cloud water for layer cloud and LSC (Le Treut & Li 1991) • K-distribution 2-stream radiation (Nakajima et al., 1995) + max.-random cloud overlap • Mellor-Yamada level 2 turbulent closure + moist effect (Smith, 1990)

  3. 1 Mar 1 Feb 1 Jan Cumulus convection in the K1 model Sensitivity to td : timescale of cloud base mass flux td= 7200s td= 3600s td= 1000s Cloud cluster is less organized with shorter lifetime Standard value of td = 7200s = 2hr

  4. Cloud water/ice in the K1 model melting layer (-25C < T < -5C) Cloud ice Cloud water Radiative budgets are sensitive to the definition of melting layer

  5. Time mean state (precipitation) Meridional SST distribution Single ITCZ except for “Flat”

  6. Time mean state (precipitation) Precipitation in the K-1 model is moderate among APE participants * cited from Dr. Williamson’s summary

  7. Main focuses in APE might be: • To evaluate the model spread due to physical parameterization • Behavior of tropical disturbances (MJO, cloud clusters) • Main focuses in our group are: • Behavior of the extratropical low-frequency variability (tomorrow afternoon session) • Tropical zonal mean state associated with an interaction between the Walker and Hadley circulations (tomorrow morning “teaser”) • Extended integrations: • Control and 3KW1 extended for 2700 days (=7.5yrs)

  8. Time mean state (precipitation)

  9. Tropical zonal mean states in APE with a special attention to the comparison between Control and 3KW1 experiments Masahiro Watanabe (Hokkaido University) hiro@ees.hokudai.ac.jp

  10. Mean tropical atmosphere in K1 Control & 3KW1 c.i.=0.01Pa/s

  11. Saravanan (1993) • This may not be effective in • more complicated models? Equatorial superrotation Results in two-level, dry primitive models Suarez & Duffy (1992)

  12. Mean tropical atmosphere in Control & 3KW1

  13. Mean tropical atmosphere in Control & 3KW1

  14. Possible Walker-Hadley interaction • Whether we can see a sudden transition to the supper-rotating state? Is there hysteresis? • Possible mechanisms • Meridional momentum transports by extratropical synoptic eddies (Suarez & Duffy 1992; Saravanan 1993) by forced tropical stationary eddies (Hoskins et al. 1999) • Vertical momentum transports linked with the Hadley cell • Role of moist processes

  15. A proposal A series of APEs(Control and 3KW1, and additionally 1KW1, 2KW1, 4KW1,….) may be useful to test a basic dynamics of the interaction between Walker and Hadley circulations, or the superrotation problem, which might be to revisit previous results in the two-level dry models (e.g. Suarez & Duffy 1992; Saravanan 1993) then to extend more recent results in aquaplanet models (e.g. Hoskins et al. 1999; Kraucunas & Hartmann 2005)

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