[MITgcm-support] Time-varying forcing and EXF package

[Madison Shankle]

Dear all,

Seeking help setting up time-varying forcing. I unfortunately can't submit jobs at the moment, so apologies for not doing more troubleshooting on my own, but at present it would be very helpful to just have my understanding of a few key parameters checked.

Background: I have a time-varying T_air.bin forcing file (dimensions nTime, nY, nX = 1000, 140, 72) where the time dimension consists of annual air temp profiles (so the entire file represents a 1000yr-long record, that varies in time). All other forcing files are kept constant. T_air varies cyclically with a periodicity of 500yr, so two cycles are contained in T_air.bin. (I made the file 1000yrs long as I typically run my simulations for 1000yrs at a time, which takes about 24hr, and I can start the next simulation the next day.)

Is my understanding of the following  parameters correct, and are there any other parameters to be changed that I have missed out?

data.exf
--> atempstartdate1 = 395000101
--> atempperiod = 31104000
Here "atempstartdate1" specifies that I have read in a T_air.bin file whose record starts on Jan 1, year 39500. (I am starting my simulations off of a previous study's output, which ran ~32000yr, from which it then took an additional ~7000yr to spin-up my simulations on ARCHER2 with some slight edits to the model configuration. So, with my model configuration properly spun up, I'm now ready to start the experimental (time-varying temp) simulation at year 39500).

data.cal
--> TheCalendar = 'model'
--> startDate1 = 395000101
Here "startDate1" tells the model which record to read first from T_air.bin. At this point, I can say that my 1000yr-long T_air record starts at 395000 (in data.exf) and this parameter tells the model to start reading from that first time step. So, I was planning on just updating these two parameters each time I start a new 1000yr-long run (e.g. to 40500, 41500, 42500, etc. each time I start a new run). However, I suppose I could also simply write a 40,000yr-long T_air file (40000,ny,nx) (as my goal is to run my simulation this long), in which case I could leave atempstartdate1 as 395000101, and only have to update data.cal's startDate1 parameter with each new model run.


Is that all correct and am I missing anything else that would need to be changed to set up a time-varying run? Apologies again; I nearly got this working before the holidays but as I said can't submit jobs at the moment, so making some progress by getting feedback from this group while I sort that out would be very appreciated.

Thanks and best wishes for the new year,
M. Shankle





-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.mitgcm.org/pipermail/mitgcm-support/attachments/20231230/45cab75b/attachment.html>