
 Here are some more suggestions for you to get to know
 Metview, this one is about computing with fields:

 The data icon 'T_an+T_fc48' contains three analysis fields and
 three forecast fields that are valid at the same time;
 here is how to compute and plot forecasting error:

 - GRIB filter icon 'an' picks only analysis fields

 - GRIB filter icon 'fc48' picks only forecast fields

 - Simple Formula icon 'Forecast error' uses icons 'an' and
    'fc48' to compute the error; check by visualising it

 - drop 'Europe lat-lon' icon into display window to select
    the right area

 - select both 'pos' and 'neg' icons and simultaneously drop
    them both into display window; now negative area are shaded
    with colder colours and positive areas with warmer colours,
    and the areas with values close to zero (-1...+1) having
    no shading
