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
Outline Introduction Sensitivity to horizontal resolution Modifications of physics Performance of simulated TCs Summary
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”
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)
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
Surface height (Asia) (m)
Surface height (Japan) (m)
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
Global annual mean (TOA) OLR Abs. Solar
Global annual mean (surface) SW LW LH SH
Global annual mean (precip) Total LS Conv. ZM
DJF 200-hPa zonal wind T42 T85 T170 T341
JJA precipitation rate
JJA precipitable water
Monthly precipitation rate (T341) Dec Jan Feb Model CMAP
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
Further modifications adjustment time scales efficiency of evaporation from LS rain surface moisture exchange inhibition mechanism of ZM scheme
Global precipitation rate Total ZM scheme RHc: RH threshold for triggering ZM Different from Maloney and Hartmann (2001)
Precip-CAPE relationship daily, 20N-20S, July, Year 0006 RHc=85% RHc=0%
Time series of CAPE/Precip at 9.4N, 138.1E (Yap Island) RHc=85% McBride and Frank (1999) suggest weak negative correlation. RHc=0%
Moist static energy profile at 9.4N, 138.1E (Yap Island) RAOBS MODEL RHc=85% RHc=0%
Simulated TC frequencies Definition 40N-40S over ocean SLP gradient warm-core structure
STC distributions
JJA Precipitation rate RHc=85% RHc=0% CMAP
Ensemble simulations T42 model with RHc=85% Observed SST from 1979 to 2000 9 members
Interannual variations
Interannual variations
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.