Dear WEAP Community,

I am experiencing ongoing difficulties importing a NetCDF (.nc) file through the Catchment Delineation mode.

Initially, WEAP reported two issues:

Irregular Grid Error – Longitude delta is not uniform.

Incorrect Dimension Order – The file was structured as (lon, lat, time) instead of the required (time, lat, lon).

I have since reordered the dimensions to (time, lat, lon) and carefully checked the file structure. The dimension order now appears correct.

However, WEAP still does not successfully load the file, and the irregular grid error persists.

Could anyone please clarify:

Does WEAP require strictly uniform longitude spacing with no floating-point variation?

Are there additional structural or metadata requirements beyond dimension order?

Is there a recommended workflow for preparing NetCDF climate files specifically for WEAP?

Any guidance would be greatly appreciated.

Thank you in advance for any advice or suggestions you can provide. I look forward to hearing from anyone with experience in similar situations.

Ioulia,

WEAP can be particularly about the way the .nc files are setup. Here is an example of a .nc file that WEAP can read. The date variable needs to be defined as days since a reference date (1900-01-01) in this case- but you can change this. Must be in format yyyy-mm-dd. Lat and Lon variables are simply defined as Y and X, respectively.

For resolving additional minor errors, assuming you are using NCO and CDO tools, AI or ChatGPT may be able to further help refine your input file.

user@FolderDirectory/Subfolder$ filename.nc
netcdf weap_monthly {
dimensions:
date = 601 ;
lat = 161 ;
lon = 118 ;
bnds = 2 ;

variables:
double date(date) ;
date:axis = "Z" ;
date:units = "days since 1900-01-01 00:00:00" ;
date:bounds = "date_bnds" ;

double lat(lat) ;
lat:axis = "Y" ;

double lon(lon) ;
lon:axis = "X" ;

double date_bnds(date, bnds) ;

double pr(date, lat, lon) ;
pr:units = "millimeters" ;
pr:_FillValue = -9999. ;
pr:missing_value = -9999. ;
pr:cell_methods = "date: sum" ;
pr:Full_Name = "Precipitation" ;

double tmax(date, lat, lon) ;
tmax:units = "degrees Celsius" ;
tmax:_FillValue = -9999. ;
tmax:missing_value = -9999. ;
tmax:cell_methods = "date: mean" ;
tmax:Full_Name = "Maximum daily temperature" ;

double tmin(date, lat, lon) ;
tmin:units = "degrees Celsius" ;
tmin:_FillValue = -9999. ;
tmin:missing_value = -9999. ;
tmin:cell_methods = "date: mean" ;
tmin:Full_Name = "Minimum daily temperature" ;
}