Interpolation time and accuracy in ERA5 data download with Netcdf format

Datasets and Usage C3S - Datasets and Usage
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1

Hi,
I’m trying to download hourly ERA5 data with 0.01 deg or 0.001 deg grid resolution in netcdf format for 6km by 6km region?

I would like to know if the interpolation in built in the data download process takes more time to process than the actual download?

What about the accuracy of interpolation used in ERA5 download compared to RegularGrid interpolator used in scipy? (RegularGridInterpolator — SciPy v1.14.0 Manual)

Also, would it be efficient to do interpolation on 0.25 deg raw ERA5 data on our own?

Regards,
Jerome

2

Hi,
You can specify a higher output resolution than the archived resolution, but the resulting data will not contain any more information than the original, it has merely been interpolated to a higher resolution. This makes the output look smoother, but does not increase the accuracy or the precision of the data. However, if you choose to interpolate to a coarser resolution than the archived resolution you should be aware that the data can be aliased, unless care was taken to avoid this.

if you intend to interpolate to a much higher resolution it is probably best to download the grib data and interpolate/convert to netCDF on your local machine.

Regards
Michela

3

If I download grib data, is there a way to convert it to regular grid, as grib data is in a reduced gaussian grid format? Will this me automatically done if i convert it locally into a NetCDF file?

Regards,
Jerome