change crop planting window dates

[xgao304]

Dear Sir:

I would like to change the minimum and maximum planting dates of some crops since the default model values are not consistent with the observations.
It seems that 1) I can change the crop dates specified in the variables "max_NH/SH_planting_date(pft)" and min_NH/SH_planting_date(pft) in the clm input params file.
2) based on the technical note, this can also be achieved through the input map stream files 'stream_fldFileName_swindow_start" and 'stream_fldFileName_swindow_end".

My questions are
1) which way should I use?
2) if I use the 2nd method, where to find those stream files and how to integrate the changes during the model build phase?
3) in the model, the phenology phase is generally determined by the GDD temperature thresholds. If I forcefully change the planting window dates, would it cause any inconsistency in the GDD-based calculation? Do I need to adjust any other relevant parameters?

Thanks,

 

[samrabin]

1) You should use the max/min_NH/SH_planting_date(pft) field on the parameter file if you're okay changing the sowing windows for all gridcells in each hemisphere. This would mean you also need to set stream_fldFileName_swindow_start and stream_fldFileName_swindow_end to the empty string ''.

2) If you want more control than that, you'll use stream_fldFileName_swindow_start and stream_fldFileName_swindow_end. By default, those point to the following files, respectively, in lnd/clm2/cropdata/calendars/processed/:

• swindow_starts_ggcmi_crop_calendar_phase3_v1.01.2000-2000.20231005_145103.tweaked_latlons.nc
• swindow_ends_ggcmi_crop_calendar_phase3_v1.01.2000-2000.20231005_145103.tweaked_latlons.nc

You can use those files as a template for making your own files. Then in your case, you would point stream_fldFileName_swindow_start and stream_fldFileName_swindow_end at your files.

3) Yes, using custom sowing windows can result in maturity requirements (the GDD thresholds you mention) that are too low or high. For example, if you move the sowing window to later in the warm season but do not reduce maturity requirement, the crop might not have enough time to reach maturity before it gets cold. If you have an idea of your typical harvest date, you can use this method to calibrate your maturity requirements based on the date at the middle of your sowing window. (Please note that the other sections on that page are out-of-date; they do not reflect that by default now the stream files for sowing window and maturity requirement are used.)

 

[samrabin]

Note that the instructions linked in (3) assume you're using the stream_fldFileName_swindow_start/end method, not the parameter file max/min_NH/SH_planting_date(pft) method.

 

[xgao304]

@samrabin: Thanks for the information. I have several further questions:

1. I currently run the crop model with all the default settings (without changing any crop calendar) using the following command. Which method is actually used to determine the crop calendar, 1) or 2)?

create_newcase --case BgcCrop2000_BANG_HisD --compset 2000_DATM%GSWP3v1_CLM50%BGC-CROP_SICE_SOCN_SROF_SGLC_SWAV --res CLM_USRDAT --user-mods-dir $MYDATA_DIR --machine svante --compiler intel --run-unsupported

My confusion is: I have neither set stream_fldFileName_swindow_start = ' ' anywhere, nor my inputdata cropdata directory contains those two files you specified (*weaked_latlons.nc). How do I know which method is actually used?

2. If I change the crop calendar using the method 1 (max/min_NH/SH_planting_date(pft) field on the parameter file), should I set stream files in user_nl_clm? For example:
stream_fldFileName_swindow_start = ' '
stream_fldFileName_swindow_end = ' '

3. If I use the method 2) to change the crop calendar, should I also specify it in "user_nl_clm"?

stream_fldFileName_swindow_start = '/XXXX/my_modified_file1.nc '
stream_fldFileName_swindow_end = ' /XXXX/my_modified_file2.nc'

Thanks,

Xiang