How to create a new grid mask

[mf99274]

Hi all,

I am literally new using pop_tools and running cesm2 so forgive me if this is a dumb question. I want to mask a part of the Pacific ocean and I have got to this point...

import matplotlib.colors as colors
import matplotlib.pyplot as plt
import numpy as np
import xarray as xr

import pop_tools`

## getting pop grid
grid_name = 'POP_gx1v7'
ds = pop_tools.get_grid(grid_name)
regions = np.array(np.unique(ds.REGION_MASK))

# ploting regions 
ds.REGION_MASK.plot.contourf(levels=regions, cmap='tab20');

mask3d = pop_tools.region_mask_3d(grid_name, mask_name='default')


# mask3d[4] is the pacific ocean
test = mask3d[4].copy()

test[275:283,149:151] = 0.
test[294:300,162] = 0.
test[286:292,161] = 0.

mask3d[4,:,:] = test

I know the path to the mask is ~/.pop_tools/inputdata/ocn/pop/gx1v7/grid/ . Thus, how do I save the file in .ieeei4 with my new mask?

Thanks