Hello,
Generally, we recommend that climate runs be 31 years or more. One year for model spin-up in which the GCM and RCM come into equilibrium (and which is not included in the analysis because of this), and three decades of data for analysis. The reason for this is that it gives the model a chance to have replicated internal natural climate variability, some of which occurs multi-decadally.
However in a pinch, because of time or lack of computing resources, 11 years can be used -- eleven is the *absolute* mininum (one year of spinup and one decade). So you could run e.g.
Dec 2029-Nov 2040 excluding Dec 2029 - Nov 2030 (as spinup) Dec 2039-Nov 2050 excluding Dec 2039 - Nov 2040 Dec 2049-Nov 2060 excluding Dec 2049 - Nov 2050 Dec 2059-Nov 2070 excluding Dec 2059 - Nov 2060
That would leave you with 40 years of climate data for analysis -- December 1 2030 to Nov 30 2070
Thanks David
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