GIAF case with datm - want to start in 1978 (instead of 1948)

[abaker@ucar_edu]

I am running a GIAF_T62_g16 case in cesm1_3_beta03, and I know that by default
the data year for the DATM starts at 1948.  What I would like to do is
have it start with 1978 instead (because we have some data
that starts in 1978 that we are temporarily incorporating into POP for
testing).

I found bits and pieces of documentation online, and so far I added this
to usr_nl_datm:

streams = "datm.streams.txt.CORE2_IAF.GCGCS.PREC 1 1978 2009",
"datm.streams.txt.CORE2_IAF.GISS.LWDN    1 1978 2009",
         "datm.streams.txt.CORE2_IAF.GISS.SWDN    1 1978 2009",
"datm.streams.txt.CORE2_IAF.GISS.SWUP    1 1978 2009",
         "datm.streams.txt.CORE2_IAF.NCEP.DN10    1 1978 2009",
"datm.streams.txt.CORE2_IAF.NCEP.Q_10    1 1978 2009",
         "datm.streams.txt.CORE2_IAF.NCEP.SLP_    1 1978 2009",
"datm.streams.txt.CORE2_IAF.NCEP.T_10    1 1978 2009",
         "datm.streams.txt.CORE2_IAF.NCEP.U_10    1 1978 2009",
"datm.streams.txt.CORE2_IAF.NCEP.V_10    1 1978 2009",


(so I changed all the 1948 starts to 1978).  But I am wondering if there
is something else I need to do because when I do to my run directory
and look in the  datm.streams.txt.* files:<br />
datm.streams.txt.CORE2_IAF.CORE2.ArcFactor 
datm.streams.txt.CORE2_IAF.NCEP.Q_10
datm.streams.txt.CORE2_IAF.GCGCS.PREC       
datm.streams.txt.CORE2_IAF.NCEP.SLP_
datm.streams.txt.CORE2_IAF.GISS.LWDN       
datm.streams.txt.CORE2_IAF.NCEP.T_10
datm.streams.txt.CORE2_IAF.GISS.SWDN       
datm.streams.txt.CORE2_IAF.NCEP.U_10
datm.streams.txt.CORE2_IAF.GISS.SWUP       
datm.streams.txt.CORE2_IAF.NCEP.V_10
datm.streams.txt.CORE2_IAF.NCEP.DN10       
datm.streams.txt.presaero.clim_2000

These have file lists that still start at 1948.  So I am not sure if
this will do the right thing or not.<br /><br />Thanks!<br />Allison<br />

 

[tcraig]

In general, the file list and the start/end/align dates are relatively independent.  A file list associated with multiple years of data can be used without change to cycle over a smaller period in that dataset by setting the start/end/align values.  You should be able to cycle the data from 1979 to 2009 where 1979 is aligned with model year 1 in your setup.  The data atm model will read the input dataset until it finds 1979 in the input dataset.  You can reduce the initial read by deleting the extra datasets from 1948-1978 from the list, but it will have no impact on the results. 

 

[abaker@ucar_edu]

Thanks Tony.  Just to clarify, if I just specify the "streams" in usr_nl_datm asI showed above (and do nothing else), then model will work how I want it to - correct?

 

[tcraig]

I believe that is true.

 

[mvertens]

I have indeed verified that putting in just your mods works correctly by looking at the output in the atm.log files.

 

[abaker@ucar_edu]

Thanks Mariana. Just a followup question for either of you.  Assume that I am running this GIAF case and I have 30 years of atm data that I am using, then if I set the model to run for 60 years, will it just loop through the atm data twice? Thanks! 

 

[mvertens]

Yes that should be the case.