Sets to NaN the dataset values corresponding to a SMOS pixel quality level > 1
The data with quality_level > 1 is considered bad quality thus is removed.
This is specified in SMOS daily product specification : https://www.smosstorm.org/content/download/139283/file/SMOS_WIND_RM_TN_v1.1_20200304_signed.pdf
Parameters
----------
dataset : xarray.Dataset already containing data cropped around cyclone.
Returns
-------
xarray.Dataset
Same dataset but with NaN sets to all variables where variable quality_level is > 1
"""
quality_col="quality_level"
# set nan to quality levels > 1 because
withnp.errstate(invalid='ignore'):# ignoring warnings caused by Nans in array