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Guidance on Running with LME datasets with CESM2.1.3 (CLM5)

wvsi3w

wvsi3w
Member
Hello,
I have some questions regarding how to run with LME data and other related inquiries that I would like to know your opinion on:

For my project, I’m using CESM 2.1.3, and I would have a combination of paleo and future scenarios in my project. I would be using data from LME (850 CE onward) and SSPs for GLOBAL and REGIONAL simulations. So it would cover 850 to 2100 (or let's say 2300, using SSP development data). I have my own soil layer structure therefore I will need to do my own spinup as the restart files from other simulations and other projects won't be useful. I am facing a few technical and strategic challenges...

1. Dataset Selection and Compatibility: I plan to use the CCSM4-based LME data (Dataset: CESM1 Last Millennium Ensemble) as atmospheric forcing for the last millennium. However, I am unclear about which specific dataset version (e.g., the “003” or “007” series). As you know in the download link of the atm 6h data there are two types of datasets, for example for the Q variable:
b.e11.BLMTRC5CN.f19_g16.007.cam.h2.Q.0850010100Z-0899123118Z.nc
b.e11.BLMTRC5CN.f19_g16.850forcing.003.cam.h2.Q.0850010100Z-0899123118Z.nc
would be optimal for this purpose and why? Also if this dataset is not compatible with CESM2.1.3 (CLM5) what do you suggest to use instead that covers 850 onward?

2- Are there recommendations on using “6-Hourly Instantaneous” vs. “6-Hourly Averaged” data for climate dynamics over this period?

3- I asked a question here in this thread regarding the process and I would like to know your thoughts on it too, what would be the steps to do a simulation using LME datasets from the beginning (setting up the case, paths, names, spinup, transient, ...), any guideline available for global simulation? I found this link for PaleoResources but I don't think it would be useful since it is for the CLM4 version.

4- Is there a different process for surface dataset generation in single-point mode for using the LME dataset?

4.1- Also (a less related question) regarding the single-point process, when people talk about "using our own forcing dataset" on the forum, they seem to simulate "single-point/regional" jobs. I wondered if it is even possible to use our forcing for global simulations or different resolutions. I mean I think it is possible but why this CLM_USRDAT_NAME method is only mentioned in the single-point simulation process?

5- What kind of vegetation dynamic would be ideal for this type of simulation? Is FATES good for it? Is there any other DV than FATES? any limitations? I am asking because one important part of my project is to have vegetation dynamics analyzed, so knowing this before running the lengthy simulation would be very beneficial and save time and energy.

6- How about coupling CLM with CAM or fully coupled CESM? can you think of a way to have any of the mentioned coupled ways using LME data in a +1000y simulation? This part is also important because some of the atmospheric variables (or circulation/pattern/teleconnection) must be analyzed too, so I will need CAM.

6.1- therefore if you had some similar experience with coupling CLM&CAM or with giving the output of CLM to CAM as initial conditions or I don’t know maybe “forcing” please let me know the general process or guidelines. Or if I am not thinking clearly and maybe this question is not correct also please notify me because I don't know if doing so "giving the output of CLM to CAM (as the initial condition)" is a way to do it. I suspect I need to have a CLM-CAM coupled run (or fully coupled) to achieve the aforementioned objectives of my project, but that's me, I need your advice.

Thanks a lot.
 

wvsi3w

wvsi3w
Member
Dear @jiangzhu I could only find your ID who I think is related to Paleo forum. I would really be grateful if you let me know what you think about these questions (specially question 1 and 2). Thanks a lot
 

wvsi3w

wvsi3w
Member
Dear Scientists,
I have a question about my LME dataset which I downloaded (9TB, 7 variables: U, V, Q, T, PS, PRECT, FLDS, FSDS):

The data was 2deg and since I needed it to be 1deg I did some re-griding (cdo remapbil,r360x180). I noticed that most people are using their own atmospheric forcing to run a single-point or regional case but my question is that can we run it globally? I think we can, but is it a different process for it? because most of the threads I read are doing it for regional studies, and I need to do it globally. If so, may I know which link or documentation I should follow?

Another question is my dataset consist of 23 netcdf files like one for 850-899 another for 900-949 and so on till 1950-2005. So I read in some threads that we need to separate the data into monthly sets or we need to reduce the number of files (forcing years) in stream file; e.g. PRECT/850-01.nc, 850-02.nc, .... 2005-12.nc
Is that right? or can I keep it like that 50 years?

It would be great to know your opinion (@oleson)
 
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