Timings

Before we can determine how long model a Earth System Model will take to run there a number of variables to consider

• how many PEs to use for each sub-model

Some key points

• Runs need to be finished by January 2018
• To run the GC2 Coupled N216-ORCA025 on Power 7 on 36 nodes still takes 20hrs to run one model year. So 750 years would still take 625 days (21 months or 1.7 years). Which would be a start date of April 2016 (no contingency).
• Colin's estimate of the UKESM1-HI being 1.42 times slower (which assumes a 1.85 times slower model, but more PEs thrown at it (~1500PEs)), predicts the code would take 900 days (30 months, 2.5 years). Which would be a start date of April 2016 (no contingency). 1.42 times slower is one model year every 28.3 hours or