SNAP documentation

CAWCR

The CAWCR files can be found in /group_workspaces/jasmin/snap/cawcr/phase1/ where we have

• Northern hemisphere files in NH_SSW. 7,200 files in this directory
• Southern hemisphere files in SH_SSW

The filename are of the form cawcr<date>en<ensemble>fch<hour.nc, where: the <date> is that starting date and is the form YYYYMMDDhh; <ensemble> is a two digit number which runs from 00 to 23; and <hour> runs from 006 to 360 (0.25 days to 15 days).

Putting each section into one file

Each section of the ensemble is put into one file with the script /home/users/stringer/snap/bin/conformCawcr.scr which requires one argument, which is the string common to all the filenames of the members of the section ensemble, e.g.

./conformCawcr.scr
/group_workspaces/jasmin/snap/cawcr/phase1/NH_SSW/cawcr2013010212en09fch

where the entry above should all be on one line. This script does the following

• Copy all the section ensemble files into the work directory, /home/users/stringer/snap/data
• Convert the doubles to floats
• Flip the lev_3 (pres_upp), so it points up like the other pressure levels. And also flip the lev_2 (theta) so it points up.
• Converts the time in hours to time in days for each file in section ensemble
• Create a list of the files which contain the hr24_prcp variable, and convert hr24_prcp from mm to m.
• Concatinate all the files together with nrcat (this will exclude hr24_prcp because it's only in a quarter of the files).
• Put the hr24_prcp data together
• In the hr24_prcp combined file rename the time dimension and variable to day, and make it a fixed dimension (so we can combine it with a file that has time as the record dimension).
• Append the hr24_prcp to our main combined file
• Remove the one element dimensions, height and height_2.
• Rename variables according to the table below

Variable name	Long name	Type	dimension	Units	New variable name	new long name
T	var130	float	time, lev, lat, lon	K	T	Temperature
u10m	var165	float	time, height, lat, lon	m/s	U10	10 metre U wind component
v10m	var166	float	time, height, lat, lon	m/s	V10	10 metre V wind component
T2m	var167	float	time, height_2, lat, lon	K	T2	2 metre temperature
EPV	var40	float	time, lev_2, lat, lon	? (becomes K m**2 kg**-1 s**-1)	PV	Potential vorticity
U	var131	float	time, lev, lat, lon	m/s	U	U velocity
V	var132	float	time, lev, lat, lon	m/s	V	V velocity
geop_ht	var129	float	time, lev, lat, lon	m	ZH* (Geopotential in ERA is Z)	Geopotential height
gwUaccSS	var30	float	time, lev_3, lat, lon	m/s2	GWUSS?*	u-acceleration from gw saturated stress
gwVaccSS	var31	float	time, lev_3, lat, lon	m/s2	GWVSS?*	v-acceleration from gw saturated stress
gwUaccBF	var36	float	time, lev_3, lat, lon	m/s2	GWUBF?*	u-acceleration from gw blocked flow
gwVaccBF	var37	float	time, lev_3, lat, lon	m/s2	GWVBF?*	v-acceleration from gw blocked flow
gwEforSP	var41	float	time, lev_3, lat, lon	m/s2	GWESP?*	eastward force from spectral gw scheme
gwNforSP	var42	float	time, lev_3, lat, lon	m/s2	GWNSP?*	northward force from spectral gw scheme
hr24_prcp	var61	float	time, lat, lon	mm (units in ERA are m)	TPR (divided hr24_precip by 86400 to get rainfall rate)	Rainfall rate
lon	longitude	double	lon	degrees_east	longitude	longitude
lat	latitude	double	lat	degrees_north	latitude	latitude
lev	pressure	double	lev	Pa	p	pressure
height	height	double	height	m	REMOVED - it was just one element equal to 10m
height_2	height	double	height_2	m	REMOVED - it was just one element equal to 2m
lev_2	isentropic	double	lev_2	K	theta	potential temperature
lev_3	pressure	double	lev_3	Pa	p_2	upper pressure levels
time		double	time	hours since 2013-01-02 12:00:00	t	time

* variable not available in ERA-Interim, so unclear what name to use