1. APE workshop at Univ. Reading, 20-22 April 2005 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. APE workshop at Univ. Reading, 20-22 April 2005 Same atmospheric model as used for IPCC FAR Dynamics –T42 spectral representation –Vertical 20  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) K-1 Japan: CCSR/NIES/FRCGC AGCM ver. 5.7

3. APE workshop at Univ. Reading, 20-22 April 2005 Cumulus convection in the K1 model Sensitivity to  d : timescale of cloud base mass flux 1 Feb 1 Mar 1 Jan Cloud cluster is less organized with shorter lifetime Standard value of  d = 7200s = 2hr  d = 1000s  d = 3600s  d = 7200s

4. APE workshop at Univ. Reading, 20-22 April 2005 Cloud water/ice in the K1 model Radiative budgets are sensitive to the definition of melting layer melting layer (-25  C < T < -5  C) Cloud ice Cloud water

5. APE workshop at Univ. Reading, 20-22 April 2005 Time mean state (precipitation) Single ITCZ except for “Flat” Meridional SST distribution

6. APE workshop at Univ. Reading, 20-22 April 2005 Time mean state (precipitation) Precipitation in the K-1 model is moderate among APE participants * cited from Dr. Williamson’s summary

7. APE workshop at Univ. Reading, 20-22 April 2005 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. APE workshop at Univ. Reading, 20-22 April 2005 Time mean state (precipitation)

9. APE workshop at Univ. Reading, 20-22 April 2005 with a special attention to the comparison between Control and 3KW1 experiments Tropical zonal mean states in APE Masahiro Watanabe (Hokkaido University) hiro@ees.hokudai.ac.jp

10. APE workshop at Univ. Reading, 20-22 April 2005 Mean tropical atmosphere in K1 Control & 3KW1 c.i.=0.01Pa/s

11. APE workshop at Univ. Reading, 20-22 April 2005 Equatorial superrotation Suarez & Duffy (1992) Results in two-level, dry primitive models Saravanan (1993) This may not be effective in more complicated models?

12. APE workshop at Univ. Reading, 20-22 April 2005 Mean tropical atmosphere in Control & 3KW1

13. APE workshop at Univ. Reading, 20-22 April 2005 Mean tropical atmosphere in Control & 3KW1

14. APE workshop at Univ. Reading, 20-22 April 2005 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. APE workshop at Univ. Reading, 20-22 April 2005 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)