Changes between Version 11 and Version 12 of Documentation/UserGuide/VerifyClimate

Timestamp:

2014-11-18T10:00:54+01:00 (9 years ago)

Author:

luyssaert

Comment:

--

Documentation/UserGuide/VerifyClimate

@@ -1 +1 @@
 Once you have run LMDZOR, the first question to ask yourself is: does the climate I'm getting make sense?  There does not seem to be any straightforward way to answer this question, so this page is going to give ideas on how to procede.
 
-Tip 1) Run a spinup of ORCHIDEE offline to get reasonable biomass and soil water pools, which seems to be fairly important if you are using the 11-layer hydrology.  The only way to do this that I know of is to regrid the driver files to the resolution you are interested in (such files now exist for the CRU dataset for 128x118) and use those to run offline for 50 years or so.  Then you can use the resulting restart files to start the LMDZOR calculation.  This is not a trivial step!  You also need to make sure that the land mask you are using matches what is found in LMDZOR.  The way we came up with to do this, was to run a one day simulation of LMDZOR without a restart and look at the resulting history files.  There are variables inside the histday*nc files called CONTFRACOR and CONTFRACATM, which contain the fraction of each gridcell which have land.  We made sure that all these pixels had climate variables in our regridded forcing files, even if it meant copying the forcing data from nearby pixels.
+'''Setting the boundary conditions'''
+Rubbish in is rubbish out so first of all the boundary conditions of the coupled simulation should be acceptable:
+* Run a spinup of ORCHIDEE offline to get reasonable biomass and soil water pools, which seems to be fairly important if you are using the 11-layer hydrology.  The only way to do this that I know of is to regrid the driver files to the resolution you are interested in (such files now exist for the CRU dataset for 128x118) and use those to run offline for 50 years or so.  Then you can use the resulting restart files to start the LMDZOR calculation.  This is not a trivial step!  You also need to make sure that the land mask you are using matches what is found in LMDZOR.  The way we came up with to do this, was to run a one day simulation of LMDZOR without a restart and look at the resulting history files.  There are variables inside the histday*nc files called CONTFRACOR and CONTFRACATM, which contain the fraction of each gridcell which have land.  We made sure that all these pixels had climate variables in our regridded forcing files, even if it meant copying the forcing data from nearby pixels.
+* It takes at least 10 simulation years to get a good idea of the climate.  It also takes some time to equilibrate the climate after starting from a restart, so it seems that you can plan on a simulation of at least 15 years: 5 years to equilibrate, and 10 years over which to calculate the average climate.
 
-Tip 2) It takes at least 10 simulation years to get a good idea of the climate.  It also takes some time to equilibrate the climate after starting from a restart, so it seems that you can plan on a simulation of at least 15 years: 5 years to equilibrate, and 10 years over which to calculate the average climate.
+''' Top of the atmosphere radiation'''
+Prior to the industrial revolution the climate was stable. Hence, for a pre-industrial coupled simulation the net radiation at the top of the atmosphere should be close to zero. Even if your model experiment does not addresses pre-industrial conditions, you should launch a pre-industrial run and check for this condition. Then the same settings for the pre-industrial run and the experiments should be used. Remember to normalize the pixels for their surface area, remember to account for both land and ocean (especially if you are an ORCHIDEE-user) and use annual mean values as energy is stored and released over the season. The variables that should cancel each other out are TOPL and TOPS in ATM.
+ 
 
 Once you have the simulation, you need to do the averaging, find data to compare to, and create graphs.  The tool ATLAS does exactly this.  I wasn't able to find much documentation on it, though.