Required software: NCL (http://www.ncl.ucar.edu/) 

create_latlon.ncl : create latlon information file latlon.nc 

sample.ncl : sample grid-box mean model data at given lat/lon 
             all variables in the history file will be sampled at given locations 

             the output variables will have dimensions like [time, station_index] or [time, lev, station_index] 

             the station index is put into the rightest dimension so that we can use CDO (https://code.zmaw.de/projects/cdo) to process the data (e.g. temporal averaging).  


### 2015-10-23 ### 

added two new sites: 

1. WLG - Mt Waliguan, CHINA,        lat=36.2879 long=100.8964 elev=3810 masl
2. OPE - Obs. Per. d'Envi., FRANCE, lat=48.5622 long=  5.5056 elev= 395 masl