CESM1 Atlantic Pacemaker Ensembles

A 10-member ensemble of CESM1 (1 degree spatial resolution) simulations in which time-evolving SST anomalies in the North Atlantic (5oN-55oN, with a linearly tapering buffer zone that extends to EQ and 60N, the Atlantic basin) are nudged to observations (NOAA Extended Reconstruction Sea Surface Temperature version 3: ERSSTv3b) during 1920-2013. In this way, the observed evolution of North Atlantic SSTs are maintained in each simulation, 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. 

All external forcings are identical to the LENS, aside from stratospheric ozone. Further details are provided in the papers below:

  • Yang D., J.M. Arblaster, G.A. Meehl, M.H. England, E.-P. Lim, S. Bates, N. Rosenbloom, 2020: Role of tropical variability in driving decadal shifts in the Southern Hemisphere summertime eddy-driven jet. J. Climate, 33, 5445–5463, doi: 10.1175/JCLI-D-19-0604.1.
  • Meehl G.A.,  A. Hu, F. Castruccio, M. H. England, S. C. Bates, G. Danabasoglu, S. McGregor, J. M. Arblaster, S. -P. Xie and N. Rosenbloom, 2021: Atlantic and Pacific tropics connected by mutually interactive decadal-timescale processes. Nat. Geosci., 14, 36-42, doi: 10.1038/s41561-020-00669-x.

A second 10-member ensemble, identical to the first but with all forcings fixed at 1920 levels, is also available.

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.NATL.ensXX / b.e11.BRCP85LENS.f09_g16.SST.restoring.NATL.ensXX, XX = 01-10 (Original Pacemakers)
    • b.e11.B20TRLENS.f09_g16.SST.restoring.NATL.1920.ensXX, XX = 01-10 (All forcings fixed at 1920 levels.)
  • Model Version: CESM1.1 Codebase | Documentation
  • Resolution: 0.9x1.25_gx1v6 (CESM nominal 1o grid)
  • Years: 1920-2013
  • Ensemble Size: 10 members
  • Time Frequencies Saved: Monthly, Daily
  • Machine: NCAR:Cheyenne and NCAR:Yellowstone
  • Compsets: B20TRLENS / BRCP85LENS
  • Additional Notes: SST anomalies (5oN-55oN) nudged to ERSSTv3b observations. All CMIP5 time-varying external, natural and anthropogenic forcings were specified in the b.e11.B20TRLENS.f09_g16.SST.restoring.NATL.ensXX / b.e11.BRCP85LENS.f09_g16.SST.restoring.NATL.ensXX ensemble. The b.e11.B20TRLENS.f09_g16.SST.restoring.NATL.1920.ensXX ensemble is identical to the original pacemaker ensemble but has all forcings fixed at 1920 levels.

Data Acquisition

  • NCAR Internal

    Location on NCAR's campaign store (accessible from NCAR CISL machines):  /glade/campaign/collections/rda/data/d651032

  • Web Access

    This data is available from the NSF NCAR Research Data Archive.