Support ERA5 forcing

[aekiss]

This issue is a continuation of an email discussion on making configurations that support ERA5 forcing, e.g. to assess the impact of the forcing dataset on the sea ice simulation.

ERA5 is available on NCI at /g/data/rt52: https://opus.nci.org.au/display/ERA5/ERA5+Community+Home
[edit: use /g/data/ik11/inputs/ERA5 instead]

• the hourly single-level data is probably what we want. This appears to be from the "reanalysis" or "HRES" dataset (as opposed to the lower-resolution "ensemble" or "EDA" dataset).
• It's 1-hourly 0.25° data (higher resolution than JRA55-do, which is 3-hourly 0.5625°), though this has been interpolated from the reanalysis grid, which is 0.28125° (31km) for HRES.
• It's currently only from 1979 onwards but data from 1950 will be available soon (cf. 1958 for JRA55-do).
• JRA55-do has a lot of adjustments relative to JRA55 to reduce drift. ERA5 doesn't have these, so we'd expect greater drift in long climate simulations. But it may be superior to JRA55-do for shorter timescales.
• for more detail see the ECMWF ERA5 documentation and download page

Replacing JRA55-do with ERA5 would require

• new grid remapping weights files (see here)
• making sure that we have physically equivalent fields (height and variable)
• discussion on whether ERA5 fields should be used for initial conditions, e.g. for SST or sea ice concentration (SIC)

and changes to

• config.yaml
• atmosphere/forcing.json
• namcouple

and possibly more, e.g.

• coming up with liquid runoff data (unless we'd be happy with JRA55-do for that)
• parameter changes for bulk formulas or whatnot.

Our configurations currently support only JRA55-do forcing: https://github.com/COSIMA/access-om2/tree/master/control
but we have some old, unsupported CORE configs here that may be useful as a reference for the changes required
https://github.com/COSIMA/1deg_core_nyf
https://github.com/COSIMA/025deg_core2_nyf
https://github.com/COSIMA/025deg_core_nyf

[aekiss]

Note that JRA55-do has velocity components, temperature and humidity all at 10m height.
Humidity and temperature are shifted from 2m in JRA55 to 10m in JRA55-do - see appendix A2 in Tsujino et al 2018.

[aekiss]

Re. using ERA5 for initial conditions: SST and SIC are available in ERA5.
But SST would need to somehow be merged with the WOA temperature initial condition that applies below the surface.
I'd also be surprised if SIC, SST IC's have much enduring effect, since the Antarctic ice nearly disappears in summer and the surface layer is so thin the SST would quickly revert to the WOA values below it.

[aekiss]

(in response to @nichannah's email)

1. I also can't find absolute (or relative) humidity in ERA5, but as you point out there is 2m dew point temperature so I guess we'd have to calculate it from that somehow.
2. temperature and dew point are at 2m - will we need to convert these to 10m as in appendix A2 in Tsujino et al 2018?
3. surface_solar_radiation_downwards and surface_thermal_radiation_downwards are probably equivalent to JRA55-do rsds and rlds. Not sure how to check that.
4. I don't know whether total precipitation includes snowfall - but if so, your suggestion to difference them to get rainfall makes sense
5. we'd need to be careful to check what's in the various ERA runoff fields - e.g. whether solid runoff is included (I'm guessing not)

[aekiss]

re. above, from TWG 21 July 2021:

1. Matt C knows how to do this calculation
2. Matt and Russ: u, v, T, q need to be at the same level (but not necessarily 10m) - may need to read in height field to do calculations. Best to calculate on the fly.
3. Russ: yes, surface_solar_radiation_downwards=rsds and surface_thermal_radiation_downwards=rlds
4. need to check this. cice needs snow separately
5. for further investigation

[nichannah]

Quick update. A new experiment has been created with update config/input files including remapping weights. I've still got some work to do to modify YATM to properly handle runtime modifications to the input fields. i.e. to calculate humidity from dew point temperature.

[AndyHoggANU]

Just wondering if this is relevant to this development?

https://confluence.ecmwf.int/display/CKB/ERA5%3A+large+10m+winds

[aekiss]

This affects <160 spacetime points in the whole dataset, so it seems a smaller issue than the backwards cyclones in JRA55 #186
The affected data was replaced by a different analysis product. I suppose that could create discontinuities with large curls, but they would be very localised and brief.

[aekiss]

For reference, here are all the variables in /g/data/rt52/era5/single-levels/reanalysis and their paths.
The chunking can vary for a given variable; the chunking for the first file in 2017 is shown.

name	longname [units]	dimensions	chunking	path
acwh	Altimeter corrected wave height [m]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/acwh/*/acwh*.nc
alnid	Near IR albedo for diffuse radiation [(0 - 1)]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/alnid/*/alnid*.nc
alnip	Near IR albedo for direct radiation [(0 - 1)]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/alnip/*/alnip*.nc
aluvd	UV visible albedo for diffuse radiation [(0 - 1)]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/aluvd/*/aluvd*.nc
aluvp	UV visible albedo for direct radiation [(0 - 1)]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/aluvp/*/aluvp*.nc
anor	Angle of sub-gridscale orography [radians]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/anor/*/anor*.nc
arrc	Altimeter range relative correction [~]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/arrc/*/arrc*.nc
asn	Snow albedo [(0 - 1)]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/asn/*/asn*.nc
awh	Altimeter wave height [m]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/awh/*/awh*.nc
bfi	Benjamin-Feir index [dimensionless]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/bfi/*/bfi*.nc
blh	Boundary layer height [m]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/blh/*/blh*.nc
cape	Convective available potential energy [J kg**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/cape/*/cape*.nc
cbh	Cloud base height [m]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/cbh/*/cbh*.nc
cdww	Coefficient of drag with waves [dimensionless]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/cdww/*/cdww*.nc
chnk	Charnock [~]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/chnk/*/chnk*.nc
cin	Convective inhibition [J kg**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/cin/*/cin*.nc
cl	Lake cover [(0 - 1)]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/cl/*/cl*.nc
crr	Convective rain rate [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/crr/*/crr*.nc
csfr	Convective snowfall rate water equivalent [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/csfr/*/csfr*.nc
cvh	High vegetation cover [(0 - 1)]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/cvh/*/cvh*.nc
cvl	Low vegetation cover [(0 - 1)]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/cvl/*/cvl*.nc
d2m	2 metre dewpoint temperature [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/2d/*/2d*.nc
dctb	Duct base height [m]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/dctb/*/dctb*.nc
deg0l	0 degrees C isothermal level (atm) [m]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/deg0l/*/deg0l*.nc
dl	Lake depth [m]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/dl/*/dl*.nc
dndza	Mean vertical gradient of refractivity inside trapping layer [m**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/dndza/*/dndza*.nc
dndzn	Minimum vertical gradient of refractivity inside trapping layer [m**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/dndzn/*/dndzn*.nc
dwi	10 metre wind direction [degrees]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/dwi/*/dwi*.nc
dwps	Wave spectral directional width for swell [dimensionless]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/dwps/*/dwps*.nc
dwww	Wave spectral directional width for wind waves [dimensionless]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/dwww/*/dwww*.nc
fal	Forecast albedo [(0 - 1)]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/fal/*/fal*.nc
fg10	10 metre wind gust since previous post-processing [m s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/10fg/*/10fg*.nc
flsr	Forecast logarithm of surface roughness for heat [~]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/flsr/*/flsr*.nc
fsr	Forecast surface roughness [m]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/fsr/*/fsr*.nc
hcc	High cloud cover [(0 - 1)]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/hcc/*/hcc*.nc
hmax	Maximum individual wave height [m]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/hmax/*/hmax*.nc
i10fg	Instantaneous 10 metre wind gust [m s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/i10fg/*/i10fg*.nc
ie	Instantaneous moisture flux [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/ie/*/ie*.nc
iews	Instantaneous eastward turbulent surface stress [N m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/iews/*/iews*.nc
ilspf	Instantaneous large-scale surface precipitation fraction [(0 - 1)]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/ilspf/*/ilspf*.nc
inss	Instantaneous northward turbulent surface stress [N m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/inss/*/inss*.nc
ishf	Instantaneous surface sensible heat flux [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/ishf/*/ishf*.nc
isor	Anisotropy of sub-gridscale orography [~]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/isor/*/isor*.nc
istl1	Ice temperature layer 1 [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/istl1/*/istl1*.nc
istl2	Ice temperature layer 2 [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/istl2/*/istl2*.nc
istl3	Ice temperature layer 3 [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/istl3/*/istl3*.nc
istl4	Ice temperature layer 4 [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/istl4/*/istl4*.nc
kx	K index [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/kx/*/kx*.nc
lai_hv	Leaf area index, high vegetation [m2 m-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/lai-hv/*/lai-hv*.nc
lai_lv	Leaf area index, low vegetation [m2 m-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/lai-lv/*/lai-lv*.nc
lblt	Lake bottom temperature [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/lblt/*/lblt*.nc
lcc	Low cloud cover [(0 - 1)]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/lcc/*/lcc*.nc
licd	Lake ice depth [m]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/licd/*/licd*.nc
lict	Lake ice temperature [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/lict/*/lict*.nc
lmld	Lake mix-layer depth [m]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/lmld/*/lmld*.nc
lmlt	Lake mix-layer temperature [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/lmlt/*/lmlt*.nc
lshf	Lake shape factor [dimensionless]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/lshf/*/lshf*.nc
lsm	Land-sea mask [(0 - 1)]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/lsm/*/lsm*.nc
lsrr	Large scale rain rate [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/lsrr/*/lsrr*.nc
lssfr	Large scale snowfall rate water equivalent [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/lssfr/*/lssfr*.nc
ltlt	Lake total layer temperature [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/ltlt/*/ltlt*.nc
mbld	Mean boundary layer dissipation [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mbld/*/mbld*.nc
mcc	Medium cloud cover [(0 - 1)]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mcc/*/mcc*.nc
mcpr	Mean convective precipitation rate [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mcpr/*/mcpr*.nc
mcsr	Mean convective snowfall rate [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mcsr/*/mcsr*.nc
mdts	Mean direction of total swell [degrees]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/mdts/*/mdts*.nc
mdww	Mean direction of wind waves [degrees]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/mdww/*/mdww*.nc
megwss	Mean eastward gravity wave surface stress [N m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/megwss/*/megwss*.nc
mer	Mean evaporation rate [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mer/*/mer*.nc
metss	Mean eastward turbulent surface stress [N m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/metss/*/metss*.nc
mgwd	Mean gravity wave dissipation [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mgwd/*/mgwd*.nc
mlspf	Mean large-scale precipitation fraction [Proportion]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mlspf/*/mlspf*.nc
mlspr	Mean large-scale precipitation rate [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mlspr/*/mlspr*.nc
mlssr	Mean large-scale snowfall rate [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mlssr/*/mlssr*.nc
mn2t	Minimum temperature at 2 metres since previous post-processing [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mn2t/*/mn2t*.nc
mngwss	Mean northward gravity wave surface stress [N m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mngwss/*/mngwss*.nc
mntpr	Minimum total precipitation rate since previous post-processing [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mntpr/*/mntpr*.nc
mntss	Mean northward turbulent surface stress [N m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mntss/*/mntss*.nc
mp1	Mean wave period based on first moment [s]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/mp1/*/mp1*.nc
mp2	Mean zero-crossing wave period [s]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/mp2/*/mp2*.nc
mper	Mean potential evaporation rate [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mper/*/mper*.nc
mpts	Mean period of total swell [s]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/mpts/*/mpts*.nc
mpww	Mean period of wind waves [s]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/mpww/*/mpww*.nc
mror	Mean runoff rate [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mror/*/mror*.nc
msdrswrf	Mean surface direct short-wave radiation flux [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/msdrswrf/*/msdrswrf*.nc
msdrswrfcs	Mean surface direct short-wave radiation flux, clear sky [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/msdrswrfcs/*/msdrswrfcs*.nc
msdwlwrf	Mean surface downward long-wave radiation flux [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/msdwlwrf/*/msdwlwrf*.nc
msdwlwrfcs	Mean surface downward long-wave radiation flux, clear sky [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/msdwlwrfcs/*/msdwlwrfcs*.nc
msdwswrf	Mean surface downward short-wave radiation flux [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/msdwswrf/*/msdwswrf*.nc
msdwswrfcs	Mean surface downward short-wave radiation flux, clear sky [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/msdwswrfcs/*/msdwswrfcs*.nc
msdwuvrf	Mean surface downward UV radiation flux [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/msdwuvrf/*/msdwuvrf*.nc
mser	Mean snow evaporation rate [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mser/*/mser*.nc
msl	Mean sea level pressure [Pa]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/msl/*/msl*.nc
mslhf	Mean surface latent heat flux [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mslhf/*/mslhf*.nc
msmr	Mean snowmelt rate [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/msmr/*/msmr*.nc
msnlwrf	Mean surface net long-wave radiation flux [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/msnlwrf/*/msnlwrf*.nc
msnlwrfcs	Mean surface net long-wave radiation flux, clear sky [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/msnlwrfcs/*/msnlwrfcs*.nc
msnswrf	Mean surface net short-wave radiation flux [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/msnswrf/*/msnswrf*.nc
msnswrfcs	Mean surface net short-wave radiation flux, clear sky [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/msnswrfcs/*/msnswrfcs*.nc
msqs	Mean square slope of waves [dimensionless]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/msqs/*/msqs*.nc
msr	Mean snowfall rate [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/msr/*/msr*.nc
msror	Mean surface runoff rate [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/msror/*/msror*.nc
msshf	Mean surface sensible heat flux [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/msshf/*/msshf*.nc
mssror	Mean sub-surface runoff rate [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mssror/*/mssror*.nc
mtdwswrf	Mean top downward short-wave radiation flux [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mtdwswrf/*/mtdwswrf*.nc
mtnlwrf	Mean top net long-wave radiation flux [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mtnlwrf/*/mtnlwrf*.nc
mtnlwrfcs	Mean top net long-wave radiation flux, clear sky [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mtnlwrfcs/*/mtnlwrfcs*.nc
mtnswrf	Mean top net short-wave radiation flux [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mtnswrf/*/mtnswrf*.nc
mtnswrfcs	Mean top net short-wave radiation flux, clear sky [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mtnswrfcs/*/mtnswrfcs*.nc
mtpr	Mean total precipitation rate [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mtpr/*/mtpr*.nc
mvimd	Mean vertically integrated moisture divergence [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mvimd/*/mvimd*.nc
mwd	Mean wave direction [Degree true]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/mwd/*/mwd*.nc
mwp	Mean wave period [s]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/mwp/*/mwp*.nc
mx2t	Maximum temperature at 2 metres since previous post-processing [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mx2t/*/mx2t*.nc
mxtpr	Maximum total precipitation rate since previous post-processing [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/mxtpr/*/mxtpr*.nc
p140121	Significant wave height of first swell partition [m]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/swh1/*/swh1*.nc
p140122	Mean wave direction of first swell partition [degrees]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/mwd1/*/mwd1*.nc
p140123	Mean wave period of first swell partition [s]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/mwp1/*/mwp1*.nc
p140124	Significant wave height of second swell partition [m]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/swh2/*/swh2*.nc
p140125	Mean wave direction of second swell partition [degrees]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/mwd2/*/mwd2*.nc
p140126	Mean wave period of second swell partition [s]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/mwp2/*/mwp2*.nc
p140127	Significant wave height of third swell partition [m]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/swh3/*/swh3*.nc
p140128	Mean wave direction of third swell partition [degrees]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/mwd3/*/mwd3*.nc
p140129	Mean wave period of third swell partition [s]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/mwp3/*/mwp3*.nc
p140208	Free convective velocity over the oceans [m s**-1]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/wstar/*/wstar*.nc
p140209	Air density over the oceans [kg m**-3]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/rhoao/*/rhoao*.nc
p1ps	Mean wave period based on first moment for swell [s]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/p1ps/*/p1ps*.nc
p1ww	Mean wave period based on first moment for wind waves [s]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/p1ww/*/p1ww*.nc
p2ps	Mean wave period based on second moment for swell [s]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/p2ps/*/p2ps*.nc
p2ww	Mean wave period based on second moment for wind waves [s]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/p2ww/*/p2ww*.nc
p53.162	Vertical integral of mass of atmosphere [kg m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vima/*/vima*.nc
p54.162	Vertical integral of temperature [K kg m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vit/*/vit*.nc
p59.162	Vertical integral of kinetic energy [J m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vike/*/vike*.nc
p60.162	Vertical integral of thermal energy [J m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vithe/*/vithe*.nc
p61.162	Vertical integral of potential+internal energy [J m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vipie/*/vipie*.nc
p62.162	Vertical integral of potential+internal+latent energy [J m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vipile/*/vipile*.nc
p63.162	Vertical integral of total energy [J m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vitoe/*/vitoe*.nc
p64.162	Vertical integral of energy conversion [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/viec/*/viec*.nc
p65.162	Vertical integral of eastward mass flux [kg m**-1 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vimae/*/vimae*.nc
p66.162	Vertical integral of northward mass flux [kg m**-1 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/viman/*/viman*.nc
p67.162	Vertical integral of eastward kinetic energy flux [W m**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vikee/*/vikee*.nc
p68.162	Vertical integral of northward kinetic energy flux [W m**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/viken/*/viken*.nc
p69.162	Vertical integral of eastward heat flux [W m**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vithee/*/vithee*.nc
p70.162	Vertical integral of northward heat flux [W m**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vithen/*/vithen*.nc
p71.162	Vertical integral of eastward water vapour flux [kg m**-1 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/viwve/*/viwve*.nc
p72.162	Vertical integral of northward water vapour flux [kg m**-1 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/viwvn/*/viwvn*.nc
p73.162	Vertical integral of eastward geopotential flux [W m**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vige/*/vige*.nc
p74.162	Vertical integral of northward geopotential flux [W m**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vign/*/vign*.nc
p75.162	Vertical integral of eastward total energy flux [W m**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vitoee/*/vitoee*.nc
p76.162	Vertical integral of northward total energy flux [W m**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vitoen/*/vitoen*.nc
p77.162	Vertical integral of eastward ozone flux [kg m**-1 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vioze/*/vioze*.nc
p78.162	Vertical integral of northward ozone flux [kg m**-1 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/viozn/*/viozn*.nc
p79.162	Vertical integral of divergence of cloud liquid water flux [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vilwd/*/vilwd*.nc
p80.162	Vertical integral of divergence of cloud frozen water flux [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/viiwd/*/viiwd*.nc
p81.162	Vertical integral of divergence of mass flux [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vimad/*/vimad*.nc
p82.162	Vertical integral of divergence of kinetic energy flux [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/viked/*/viked*.nc
p83.162	Vertical integral of divergence of thermal energy flux [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vithed/*/vithed*.nc
p84.162	Vertical integral of divergence of moisture flux [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/viwvd/*/viwvd*.nc
p85.162	Vertical integral of divergence of geopotential flux [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vigd/*/vigd*.nc
p86.162	Vertical integral of divergence of total energy flux [W m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vitoed/*/vitoed*.nc
p87.162	Vertical integral of divergence of ozone flux [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/viozd/*/viozd*.nc
p88.162	Vertical integral of eastward cloud liquid water flux [kg m**-1 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vilwe/*/vilwe*.nc
p89.162	Vertical integral of northward cloud liquid water flux [kg m**-1 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vilwn/*/vilwn*.nc
p90.162	Vertical integral of eastward cloud frozen water flux [kg m**-1 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/viiwe/*/viiwe*.nc
p91.162	Vertical integral of northward cloud frozen water flux [kg m**-1 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/viiwn/*/viiwn*.nc
p92.162	Vertical integral of mass tendency [kg m**-2 s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/vimat/*/vimat*.nc
phiaw	Normalized energy flux into waves [dimensionless]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/phiaw/*/phiaw*.nc
phioc	Normalized energy flux into ocean [dimensionless]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/phioc/*/phioc*.nc
pp1d	Peak wave period [s]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/pp1d/*/pp1d*.nc
ptype	Precipitation type [code table (4.201)]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/ptype/*/ptype*.nc
rsn	Snow density [kg m**-3]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/rsn/*/rsn*.nc
sd	Snow depth [m of water equivalent]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/sd/*/sd*.nc
sdfor	Standard deviation of filtered subgrid orography [m]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/sdfor/*/sdfor*.nc
sdor	Standard deviation of orography [~]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/sdor/*/sdor*.nc
shts	Significant height of total swell [m]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/shts/*/shts*.nc
shww	Significant height of wind waves [m]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/shww/*/shww*.nc
siconc	Sea ice area fraction [(0 - 1)]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/ci/*/ci*.nc
skt	Skin temperature [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/skt/*/skt*.nc
slor	Slope of sub-gridscale orography [~]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/slor/*/slor*.nc
slt	Soil type [~]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/slt/*/slt*.nc
sp	Surface pressure [Pa]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/sp/*/sp*.nc
src	Skin reservoir content [m of water equivalent]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/src/*/src*.nc
sst	Sea surface temperature [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/sst/*/sst*.nc
stl1	Soil temperature level 1 [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/stl1/*/stl1*.nc
stl2	Soil temperature level 2 [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/stl2/*/stl2*.nc
stl3	Soil temperature level 3 [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/stl3/*/stl3*.nc
stl4	Soil temperature level 4 [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/stl4/*/stl4*.nc
swh	Significant height of combined wind waves and swell [m]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/swh/*/swh*.nc
swvl1	Volumetric soil water layer 1 [m3 m-3]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/swvl1/*/swvl1*.nc
swvl2	Volumetric soil water layer 2 [m3 m-3]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/swvl2/*/swvl2*.nc
swvl3	Volumetric soil water layer 3 [m3 m-3]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/swvl3/*/swvl3*.nc
swvl4	Volumetric soil water layer 4 [m3 m-3]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/swvl4/*/swvl4*.nc
t2m	2 metre temperature [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/2t/*/2t*.nc
tauoc	Normalized stress into ocean [dimensionless]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/tauoc/*/tauoc*.nc
tcc	Total cloud cover [(0 - 1)]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/tcc/*/tcc*.nc
tciw	Total column cloud ice water [kg m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/tciw/*/tciw*.nc
tclw	Total column cloud liquid water [kg m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/tclw/*/tclw*.nc
tco3	Total column ozone [kg m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/tco3/*/tco3*.nc
tcrw	Total column rain water [kg m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/tcrw/*/tcrw*.nc
tcslw	Total column supercooled liquid water [kg m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/tcslw/*/tcslw*.nc
tcsw	Total column snow water [kg m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/tcsw/*/tcsw*.nc
tcw	Total column water [kg m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/tcw/*/tcw*.nc
tcwv	Total column water vapour [kg m**-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/tcwv/*/tcwv*.nc
tmax	Period corresponding to maximum individual wave height [s]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/tmax/*/tmax*.nc
totalx	Total totals index [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/totalx/*/totalx*.nc
tplb	Trapping layer base height [m]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/tplb/*/tplb*.nc
tplt	Trapping layer top height [m]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/tplt/*/tplt*.nc
tsn	Temperature of snow layer [K]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/tsn/*/tsn*.nc
tvh	Type of high vegetation [~]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/tvh/*/tvh*.nc
tvl	Type of low vegetation [~]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/tvl/*/tvl*.nc
u10	10 metre U wind component [m s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/10u/*/10u*.nc
u100	100 metre U wind component [m s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/100u/*/100u*.nc
u10n	Neutral wind at 10 m u-component [m s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/u10n/*/u10n*.nc
ust	U-component stokes drift [m s**-1]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/ust/*/ust*.nc
v10	10 metre V wind component [m s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/10v/*/10v*.nc
v100	100 metre V wind component [m s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/100v/*/100v*.nc
v10n	Neutral wind at 10 m v-component [m s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/v10n/*/v10n*.nc
vst	V-component stokes drift [m s**-1]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/vst/*/vst*.nc
wdw	Wave spectral directional width [dimensionless]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/wdw/*/wdw*.nc
wind	10 metre wind speed [m s**-1]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/wind/*/wind*.nc
wmb	Model bathymetry [m]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/wmb/*/wmb*.nc
wsk	Wave spectral kurtosis [dimensionless]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/wsk/*/wsk*.nc
wsp	Wave spectral peakedness [dimensionless]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/wsp/*/wsp*.nc
wss	Wave Spectral Skewness [dimensionless]	('time', 'latitude', 'longitude')	[149, 73, 144]	/g/data/rt52/era5/single-levels/reanalysis/wss/*/wss*.nc
z	Geopotential [m2 s-2]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/z/*/z*.nc
zust	Friction velocity [m s**-1]	('time', 'latitude', 'longitude')	[93, 91, 180]	/g/data/rt52/era5/single-levels/reanalysis/zust/*/zust*.nc

[aekiss]

Here are the biases in the monthly 1993-2017 climatology of JRA55-do 1.4.0 tas (10m air temperature) minus ERA5 t2m (2m air temperature), plotted at 2 different colour scales.

JRA55-do is very much warmer (>30 degrees!) over Antarctica, and also has positive and negative biases of around 5 degrees extending into the Southern Ocean in winter and spring. I imagine this is mostly due to the low-temperature cutoff applied to Antarctic temperature, and smoothing in the marginal ice zone (see sec 3.3.4 of Tsujino et al 2018 and below), but figs 6b and 7a show that these changes are purely positive in August over the Southern Ocean whereas we see a mix of positive and negative. Some of the difference could also be due to the differing measurement height.

JRA55-do is cooler in the Arctic, especially in winter. Outside the polar regions it is a fraction of a degree warmer over oceans.

The large difference in polar winters suggests significant differences in the representation of sea ice and its effect on the atmosphere.

Tsujino et al 2018 Fig 6:

Tsujino et al 2018 Fig 7:

[scrallen]

@aekiss Nice plots, this is really interesting. The high latitudes differences are obviously striking.

I showed this at BoM this week. Paul Sandery was there and he pointed out that the very large positive (>10°C) biases in Antarctica appear to be over land, so perhaps the JRA55-do team didn't give that much consideration given it's meant for ocean models. Tsujino et al. appear to mask out land areas.

• But the ~5° positive and negative biases you found in Weddell and Ross-Amundsen-Bellingshausen are far from small.
• And then there's the Arctic...
• And the small positive bias to JRA55 over non-polar latitudes is interesting, even without considering what the height difference should mean:
  • Should we expect a negative lapse rate over the lower marine boundary layer? Well-mixed? In which case JRA55 should be colder by fractions of a degree that probably less than what I think you've shown and these are real biases.

I understand the height difference is what made you analyse air temps first. Are you considering any similar analysis for other fields?

At a Thursday meeting a few weeks back when this was discussed I think I recall @nichannah saying he felt he was close to a first run with ERA5. Is that the case? Or still a few things to resolve first?

[aekiss]

Hi @scrallen, yes I'll also compare the other fields we will use to drive the model.

@nichannah is converging on a working configuration but hit a few unexpected snags that required code changes. Also, we are yet to resolve how to shift the temperature from 2m to 10m, and calculate 10m relative specific humidity from 2m dew point.