Important notes regarding the 'control' simulation:

• The 'control' simulation has constant external forcings, representative of (approximately) pre-industrial conditions (though, for example, the vegetation cover is set to present day).
• In the SO&P web archive we have 1010 years of data from the 'control' simulation. The 'control' simulation actually began 750 years earlier, so essentially we have years 751 to 1760 of the simulation (these are not calendar years!). Even at this stage in the simulation, there are some residual climate drifts (trends) in certain variables.
• What does the "year" in the control simulation mean? In the actual netCDF data files provided by the Hadley Centre, the first year of the 'control' run was given the year nominal year "1530", and so the years 751 to 1760 that we have are given nominal years "2280" to "3289". The 'nat' simulation was started from the 1000th year of the 'control' simulation (nominal year "2529" in the netCDF files). The 'nat' simulation is associated with specific calendar years (because the time series of external forcings represents calendar years 1492-1999). Therefore, to compare the 'nat' run with the 'control' run, we need to compare calendar years 1492-1999 with 'control' run nominal years "2529"-"3036" (in fact, in SO&P we are using calendar years 1500-1999, which can be compared with 'control' run nominal years "2537"-"3036"). The 'all' simulation begins in calendar year 1750, and because it starts from the calendar year 1750 conditions of the 'nat' run, its relationship with the control run is the same (i.e., calendar years 1750-1999 should be compared with 'control' run nominal years "2787"-"3036"). The following table may help:
  

  Year conversions	nominal year in netCDF files	year of the control run	corresponding calendar year of nat/all runs
  start of control run	"1530"	1	N/A
  start of control run data held by SO&P	"2280"	751	1243 AD
  start of nat run	"2529"	1000	1492 AD
  start of nat run data used by SO&P	"2537"	1008	1500 AD
  start of all run	"2787"	1258	1750 AD
  end of nat and all runs	"3036"	1507	1999 AD
  end of control run data held by SO&P	"3289"	1760	2252 AD

  
  
• To simplify things, just subtract 1037 from the nominal year stored in the 'control' run data files to convert it to a calendar year for comparison with the 'nat' and 'all' simulations. In the time series files this has already been done.