Sensitivity of Modeled Dynamics to Atmosphere and Ocean Resolution in CESM Aurthors , NCAR CGD

1. Sensitivity of Modeled Dynamics to Atmosphere and Ocean Resolution in CESM Aurthors, NCAR CGD Motivation text... Experiment Descriptions ENSO Variability SST Climatology Nino 3.4 Power Spectra • CESM using CAM5-SE coupled to POP2 at high (hr) and standard (sr) resolutions • hr atmosphere, hr ocean: ne-120 (~0.25 deg), t-12 (~0.1deg) • hr atmosphere, sr ocean: ne-120 (~0.25 deg), gx1v6 (~1.0 deg) • sr atmosphere, sr ocean: ne-30 (~1.0 deg), gx1v6 (~1.0 deg) DJF Comp. SST, Tair, SLP Ann SST EQ Pacific Gray - HadISST Red – Reynolds and Smith hr atm, hr ocn Transient Behavior Pot. Temp Anom from IC Surface Temperature TOM Energy Flux hr atm, hr ocn decreased ocn res hr atm, srocn decreased ocn & atmos res hr atm, srocn still drifting at surface! decreased atmos res sratm, srocn sratm, srocn • hr atm, hr ocnhas better depiction of SST compared to hr atm, srocn&sratm, srocn • ...and better zonal SST gradient compared to sratm, srocn • Surface temperature reaches quasi-equillibrium in hr atm, hr ocn& sratm, srocn; hr atm, srocn still warming • TOM EF > 0 and trending down for all. End of run: hr atm, hr ocn (~0.3Wm-2) < sratm, srocn (~0.5Wm-2) < hr atm, srocn (~0.6Wm-2) Observations Annual Mean Bias SLP CI: 2hPa SST (obs. HadISST 1999-2008) Surface Stress (obs. ERS 1992-2000) Precip(obs. GPCP 1979-2009) oC • Shape and amplitude of Nino 3.4 power specra in hr atm, hr ocean resembles obs - hr atm, srocn & sratm, srocn have too much variance and are too periodic • SLP tele-connection amplitude is degraded compared to hr atm, srocn & sratm, srocnhowever reasons are unclear hr atm, hr ocn hr atm, srocn Summary and discussion Winter Mean MLD Bias (obs. Reynolds and Smith) sratm, srocn oC mm day-1 Nm-2 Observations oC Nm-2 mm day-1 • Global mean and rms SST bias is... • Precipitation biases... • Wind stress... m