data_vars ["sigma4"]

sigma4

cmap	'cmo.dense'
name	None
alt_names
squeeze	None
search_order	'sn'
add_loc	False

["attrs"]

standard_name	'sea_water_potential_density'
long_name	'Sea water potential density with ref at 4000 dbar'
units	'kg m-3'

["select"]

Empty dictionary