Pre-industrial and mid-Pliocene simulations with NorESM-L: AGCM simulations
- 1Bjerknes Centre for Climate Research, Allegaten 55, 5007, Bergen, Norway
- 2UNI Research, Allegaten 55, 5007, Bergen, Norway
- 3Nansen-Zhu International Research Center, Institute of Atmospheric Physics, Chinese Academy of Sciences, 100029, Beijing, China
Abstract. In the Pliocene Model Intercomparison Project (PlioMIP), two sets of experiments are suggested. One includes a reference and a mid-Pliocene experiment run with atmosphere general circulation models (AGCM experiments, referred to as Experiments I), the other includes a pre-industrial and a mid-Pliocene experiment run with coupled ocean-atmosphere general circulation models (AOGCM experiments, referred to as Experiments II). In this paper, we describe the AGCM experiments with the atmosphere component in the low-resolution version of the Norwegian Earth System Model (NorESM-L), and also assess the potential uncertainties in analyzing mid-Pliocene climate anomalies that might result from the choice of the sea surface temperature (SST) forcing for the reference experiment (pre-industrial or modern). We carry out a mid-Pliocene experiment, a control experiment forced by the modern SST fields, and a pre-industrial experiment forced by the monthly SST fields from HadISST averaged between 1879 and 1900. Our experiments illustrate that the simulated mid-Pliocene global mean annual surface air temperature (SAT) is 17.1 °C. It is 2.5 °C warmer than the control experiment, but 2.7 °C warmer than the pre-industrial experiment. We find that the uncertainties in analyses of mid-Pliocene climate anomalies are small on a global scale, but still large on a regional scale. On the regional scale, these uncertainties should be noted and assessed in future PlioMIP studies.