CESM2 Pacific Pacemaker Ensemble

A 10-member ensemble of CESM2 (1 degree spatial resolution) simulations in which time-evolving SST anomalies in the eastern tropical Pacific are nudged to observations (NOAA Extended Reconstruction Sea Surface Temperature version 5: ERSSTv5) during 1880-2019. 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. In the East Pacific, the nudging is full strength between 15S-15N and from the dateline to the American coast with a 5 degree latitude buffer region to the south and north where the strength of the relaxation is linearly reduced. West of the dateline, the nudging mask takes the form of a wedge shape, tapering off in latitude toward the Maritime continent. More information can be found at https://www.cesm.ucar.edu/working_groups/CVC/simulations/cesm2-pacific_pacemaker.html