Hi all, I want to quantify precipitation in a watershed with shapefile using WRF output. The coordinate system of my shapefile is WGS84(with lat and lon, no projection).
I learned that WRF uses perfect sphere(+a=6370000.0,+b=6370000.0), WGS 84 uses a datum(+a=6378137.000,+b=6356752.314).
My steps are:
1. Generate a reinterpolation grid(a new NC file) using "xesmf.regridder" from wrfout, (9km in wrf domain, to 0.1 degree lat/lon)
2. Clip the new NC file with shapefile in a watershed
3. Calculate weight based on lat
4. Calculate the weighted mean of precipitation in a watershed
Then I realized the difference between the perfect sphere used in WRF and the datum used in WGS84. Maybe I can not use the lat/lon directly. I am not familiar with the coordinate system and transformation.
Does anyone know whether I should do a datum transformation? If I should, how can I do it?
Thanks for your time!
Xiao
I learned that WRF uses perfect sphere(+a=6370000.0,+b=6370000.0), WGS 84 uses a datum(+a=6378137.000,+b=6356752.314).
My steps are:
1. Generate a reinterpolation grid(a new NC file) using "xesmf.regridder" from wrfout, (9km in wrf domain, to 0.1 degree lat/lon)
2. Clip the new NC file with shapefile in a watershed
3. Calculate weight based on lat
4. Calculate the weighted mean of precipitation in a watershed
Then I realized the difference between the perfect sphere used in WRF and the datum used in WGS84. Maybe I can not use the lat/lon directly. I am not familiar with the coordinate system and transformation.
Does anyone know whether I should do a datum transformation? If I should, how can I do it?
Thanks for your time!
Xiao