1) qsw + qlw :

Download 1.5*1.5 daily fields from:
http://apps.ecmwf.int/datasets/data/interim_full_daily/
step 12
Surface thermal radiation downwards
Surface solar radiation downwards
Download 00:00 --> output_step12_0h.nc
Download 12:00 --> output_step12_12h.nc
Run prep_eraint_qsw_qlwforcings.sh

2) snow + precip:

Download 1.5*1.5 synoptic monthly means from :
http://apps.ecmwf.int/datasets/data/interim_full_mnth/
step 12 
Snowfall
Total precipitation
Download 00:00 --> output_step12_0h.nc
Download 12:00 --> output_step12_12h.nc
Run prep_eraint_prlr_prsn_forcings.sh

3) t2 + q2

Download 1.5*1.5 resolution 6h fields from :
http://apps.ecmwf.int/datasets/data/interim_full_daily/
step 0
2 metre temperature
2 metre dewpoint temperature
Surface pressure
Area : 90S 90N 0E 360E
Download 00:00, 06:00, 12:00, 18:00 --> output_step0.nc
Run prep_eraint_t2_q2_forcings.sh
Run comp_q2.sh

4) Interp qsw + qlw + snow + precip + t2 + q2
Run interp_eraint.sh

5) u10 + v10

Download original resolution 6h fields :
step 0
10 metre U wind component 
10 metre V wind component
00:00, 06:00, 12:00, 18:00 --> output.grib
by running download_u10v10.py
If you use download_u10v10.py for the first time, you need to 
install you API key as described here : 
https://software.ecmwf.int/wiki/display/WEBAPI/Accessing+ECMWF+data+servers+in+batch
Run prep_eraint_u10_v10_forcings.sh

6) Surface wind perturbations:

(To save time, you can go to nanna:/scratch/virginie/wndpert and copy all the data
from this directory)
Run wndpert.sh including for the year preceeding and following the years you
aim at treating
Run rotate_perturb.sh
Run addpert_eraint.sh