Climate Variability & Change
Working Group CVCWG

CESM1 Pacific Pacemaker Ensemble

A 20-member ensemble of CESM1 (1 degree spatial resolution) simulations in which time-evolving SST anomalies in the eastern tropical Pacific (10S–10N, 160–90W, with a linearly tapering buffer zone that extends to 20S and 20N, 180W to the American coast) are nudged to observations (NOAA Extended Reconstruction Sea Surface Temperature version 3: ERSSTv3b) during 1920-2013. In this way, the observed evolution of ENSO is maintained in each simulation (i.e., ENSO is the pacemaker), with the rest of the model’s coupled climate system free to evolve. Note that only the SST anomalies, not the total SST, are nudged to observations, maintaining the model’s mean state, including any model biases. Further details are provided in the two papers below:

  • Deser, C., I. R. Simpson, K. A. McKinnon and A. S. Phillips, 2017: The Northern Hemisphere extra-tropical atmospheric circulation response to ENSO: How well do we know it and how do we evaluate models accordingly? J. Climate, 30, 5059-5082, doi: 10.1175/JCLI-D-16-0844.1.
    [Article] [Corrigendum]
  • Deser, C., R. Guo and F. Lehner, 2017: The relative contributions of tropical Pacific sea surface temperatures and atmospheric internal variability to the recent global warming hiatus. Geophys. Res. Lett., doi: 10.1002/2017GL074273.
    [Article] [Supplementary Material]

We kindly ask that you reference one of these papers and acknowledge the CVCWG when presenting results based on the CESM1 Pacemaker Ensemble in either oral and written form.

Project Details

  • Simulation Names:
    • b.e11.B20TRLENS.f09_g16.SST.restoring.ensXX / b.e11.BRCP85LENS.f09_g16.SST.restoring.ensXX, XX = 01-20
  • Model Version: CESM1.1 Codebase | Documentation
  • Resolution: 0.9x1.25_gx1v6 (CESM nominal 1o grid)
  • Years: 1920-2013
  • Ensemble Size: 20 members
  • Time Frequencies Saved: Monthly, Daily
  • Machine: NCAR:Cheyenne and NCAR:Yellowstone
  • Compsets: B20TRLENS / BRCP85LENS
  • Additional Notes: SST anomalies (20°N-20°S,180-80°W) nudged to ERSSTv3b observations. All CMIP5 time-varying external, natural and anthropogenic forcings were specified in this ensemble.

Data Acquisition

The CESM1 Pacific Pacemaker 20-member ensemble is available from the HPSS accessed from the NCAR machine cheyenne at /CCSM/csm/PAC-PACEMAKER. If you do not have access to cheyenne you can contact the CVCWG liaisons for assistance.