NaN values in relative humidity and vertical velocity

[SauryChen]

Some of the variables downloaded from gs://weatherbench2/datasets/era5/1959-2023_01_10-6h-240x121_equiangular_with_poles_conservative.zarr contain NaN values. For example, relative_humidity_1992 and 2008, and vertical_velocity_1998. I have checked the data with both netCDF package and xarray package.

import xarray as xr
import netCDF4 as nc
data_dir = 'relative_humidity_1992.nc'
f = nc.Dataset(data_dir)
rh = np.array(f.variables['relative_humidity'])
# data = xr.open_dataset(data_dir)
# rh = data['relative_humidity'].values
rh_check = rh[744,:,:,:]

This issue is related with other two issues: #124 #161