NetCDF: working with fieldlists

We read a NetCDF file containing 3 variables on pressure levels on a 2D latitude-longitude grid. First we ensure the example file is available.

import earthkit.data as ekd

ekd.download_example_file("tuv_pl.nc")

ds = ekd.from_source("file", "tuv_pl.nc").to_fieldlist()

Our NetCDF data is represented as a FieldList consisting of NetCDFFields. Field in this context means a 2D geographical coverage (horizontal slices).

Iteration

We can itearte through the fields (we use the first 3 fields for simplicity):

for f in ds[:3]:
    print(f)

Field(t, 2018-08-01 12:00:00, 2018-08-01 12:00:00, 0:00:00, 1000, pressure, 0, None)
Field(t, 2018-08-01 12:00:00, 2018-08-01 12:00:00, 0:00:00, 850, pressure, 0, None)
Field(t, 2018-08-01 12:00:00, 2018-08-01 12:00:00, 0:00:00, 700, pressure, 0, None)

Inspecting the contents

len(ds)

18

ds.ls()

	parameter.variable	time.valid_datetime	time.base_datetime	time.step	vertical.level	vertical.level_type	ensemble.member	geography.grid_type
0	t	2018-08-01 12:00:00	2018-08-01 12:00:00	0 days	1000	pressure	0	None
1	t	2018-08-01 12:00:00	2018-08-01 12:00:00	0 days	850	pressure	0	None
2	t	2018-08-01 12:00:00	2018-08-01 12:00:00	0 days	700	pressure	0	None
3	t	2018-08-01 12:00:00	2018-08-01 12:00:00	0 days	500	pressure	0	None
4	t	2018-08-01 12:00:00	2018-08-01 12:00:00	0 days	400	pressure	0	None
5	t	2018-08-01 12:00:00	2018-08-01 12:00:00	0 days	300	pressure	0	None
6	u	2018-08-01 12:00:00	2018-08-01 12:00:00	0 days	1000	pressure	0	None
7	u	2018-08-01 12:00:00	2018-08-01 12:00:00	0 days	850	pressure	0	None
8	u	2018-08-01 12:00:00	2018-08-01 12:00:00	0 days	700	pressure	0	None
9	u	2018-08-01 12:00:00	2018-08-01 12:00:00	0 days	500	pressure	0	None
10	u	2018-08-01 12:00:00	2018-08-01 12:00:00	0 days	400	pressure	0	None
11	u	2018-08-01 12:00:00	2018-08-01 12:00:00	0 days	300	pressure	0	None
12	v	2018-08-01 12:00:00	2018-08-01 12:00:00	0 days	1000	pressure	0	None
13	v	2018-08-01 12:00:00	2018-08-01 12:00:00	0 days	850	pressure	0	None
14	v	2018-08-01 12:00:00	2018-08-01 12:00:00	0 days	700	pressure	0	None
15	v	2018-08-01 12:00:00	2018-08-01 12:00:00	0 days	500	pressure	0	None
16	v	2018-08-01 12:00:00	2018-08-01 12:00:00	0 days	400	pressure	0	None
17	v	2018-08-01 12:00:00	2018-08-01 12:00:00	0 days	300	pressure	0	None

Slicing

Standard Python slicing is available.

g = ds[1]
g

Field

data

number_of_values	84
array_type	ndarray
array_dtype	float64

parameter

variable	t
units	kelvin

time

valid_datetime	2018-08-01 12:00:00
base_datetime	2018-08-01 12:00:00
step	0:00:00

vertical

level	850
layer	None
level_type	pressure

ensemble

member

0