1. Climate sensitivity of the CCM3 to horizontal resolution and interannual variability of simulated tropical cyclones
J. Tsutsui, K. Nishizawa,H. Kitabata, Y. Yoshida
(CRIEPI, Japan)
Acknowledgement
NCAR/CRIEPI collaborative research
Support from MEXT (Japanese government)
MEXT: Ministry of Education, Culture, Sports, Science and Technology

2. Outline Introduction Sensitivity to horizontal resolution
Modifications of physics
Performance of simulated TCs
Summary

3. Background / Motivation
Preparations for IPCC AR4
contribution to scenario runs
emphasis on regional aspects and extreme events
large natural variability and model to model differences
Computing resource
Japanese “Earth Simulator”

4. Objectives To prepare higher resolution models
CO2 scenario runs
time-slice runs
To investigate models’ performance
sensitivity to various configurations
regional aspects
tropical cyclones (TCs)

5. Model configurations Migrating to CAM2 Based on CCM3.6
Optimized for vector machines
T42 to T341, L18 and L26
Modifications to physics
cloud diagnostics
precipitation processes
surface exchange of moisture
Migrating to CAM2

6. Surface height (Asia)
(m)

7. Surface height (Japan)
(m)

8. Preliminary tuning Resolution time step (s) 1200 600 180 120
T42/L18
1200
T85/L18
600
T170/L26
180
T341/L26
120
Min.RH_low
0.90
0.87
Min.RH_high
0.70
0.65
0.50
Adj.T_hack (s)
3600
1800
540
450
Adj.T_zm (s)
7200
900

9. Global annual mean (TOA)
OLR
Abs. Solar

10. Global annual mean (surface)SW LW LH SH

11. Global annual mean (precip)
Total LS
Conv. ZM

12. DJF 200-hPa zonal wind
T42
T85
T170
T341

13. JJA precipitation rate

14. JJA precipitable water

15. Monthly precipitation rate (T341)
Dec
Jan
Feb
Model
CMAP

16. Changes in higher resolutions
Global properties
increased precipitation
decreased water vapor
decreased cloud amount
negative energy budget
Large-scale fields
not much different
deficiencies left unchanged
Regional aspects
realistic, but large-scale dependent

17. Further modifications
adjustment time scales
efficiency of evaporation from LS rain
surface moisture exchange
inhibition mechanism of ZM scheme

18. Global precipitation rate
Total
ZM scheme
RHc: RH threshold for triggering ZM
Different from Maloney and Hartmann (2001)

19. Precip-CAPE relationship
daily, 20N-20S, July, Year 0006
RHc=85%
RHc=0%

20. Time series of CAPE/Precip
at 9.4N, 138.1E
(Yap Island)
RHc=85%
McBride and Frank (1999) suggest weak negative correlation.
RHc=0%

21. Moist static energy profile
at 9.4N, 138.1E (Yap Island)
RAOBS
MODEL
RHc=85%
RHc=0%

22. Simulated TC frequencies
Definition
40N-40S over ocean
SLP gradient
warm-core structure

23. STC distributions

24. JJA Precipitation rate
RHc=85%
RHc=0%
CMAP

25. Ensemble simulations T42 model with RHc=85%
Observed SST from 1979 to 2000
9 members

26. Interannual variations

27. Interannual variations

28. Summary Increased horizontal resolution results in
more transparent for LW (could be tuned),
overestimated precipitation,
detailed regional climate with similar large-scale.
Partition change in convection affects
characteristic in the tropics,
frequencies of simulated TC (not depend on resolutions).
Interannual variations of simulated TCs show
successful simulation for some seasonal activity,
model's usefulness to study TC variability.