Exception: coordinate lev is non-uniform

[ngyawali]

Hi,

I am trying to work on the 11_Omega_equation.ipynb notebook. I am currently experiencing "Exception: coordinate lev is non-uniform". The dataset I am using has the following pressure levels array([100000., 97500., 95000., 92500., 90000., 87500., 85000., 82500., 80000., 77500., 75000., 72500., 70000., 65000., 60000., 55000.,50000., 45000., 40000., 35000., 30000., 25000., 20000.])

Do I need to make those levels uniform or is there any other way I could work on this issue without changing the current levels?

[miniufo]

Hi @ngyawali, thanks for your interests. The xinvert package is built on finite difference schemes. So it would be more accurate if the grid interval is uniform. In your case, I would interpolate the whole dataset into a vertically uniform one, with a interval of 25hPa. This is not too hard if you use xarray:

dset_new = dset.interp({'lev': np.linspace(100000, 20000, 33)})

or just interpolate those variables you need, if you feel that interpolation of the whole dataset is memory consuming.

A secondary choice is to use a interval of 50hPa, and you only need to drop off those data at 975, 925, 875, 825, 775, and 725 hPas. This is also easy with xarray's .sel({'lev': np.linspace(100000, 20000, 17)})

Maybe I could do this interpolation internally. But I feel that let the user know what is happening is much better.