1. What is Tier 1 experiment? 

  1. Present decade conditions (2006-2015/6; 50- to 100-member ensembles). Taking note to include the most recent El Nino event. This would give sample sizes of between 500-1000 years, thereby allowing the 50-year return period of an extreme event to be calculated. Many centres may have already performed these integrations under AMIP or C20C experiments.
  2. 0.7oC warmer than 2006-2015 conditions (50- to 100-member ensembles).
  3. 1.2oC warmer than 2006-2015 conditions (50- to 100-member ensembles). These projections would use the weighted multi-model mean of the CMIP5 projected SST patterns (i.e. no measure of SST pattern response uncertainty).

2.  What is Tier 2 experiment?

  1. As in Tier 1 but using the individual estimates of SST response patterns from different CMIP-5 models, in each case weighting RCP2.6 and RCP4.5 models to give global mean warming of 0.7oC warmer than 2006-2015 (min 10-member ensembles). This would give a measure of the impact of uncertainty in the pattern of large-scale warming, conditioned on a specific global temperature change, consistent with research demanded by the UNFCCC call.
  2. As in previous, but for 1. 2oC warmer than 2006-2015 (min 10-member ensembles).

3. Where can I find model output details?

  1. A list of model outputs details can be found here