E3.1 Try the search facilities in the data examiners

  - Examine the GRIB file and the BUFR file; press CTRL-F to
    initiate the search. Look carefully at the options!


E3.2 Create your own GRIB Examiner key profile

  - When you examine a GRIB file, a list of 'keys' is used to display
    the GRIB messages - one key per column

  - These columns are configurable - a 'key profile' is a set of
    keys, and you can create as many of them as you want. It can
    be very useful to have different key profiles for different tasks

  - From the user interface in the GRIB Examiner, create a new key
    profile; starting either from scratch, or else from a duplicate of
    the default profile 

  - Note that the Display Window also operates on the same principles,
    and you can share key profiles between the two.


E3.3 Geopoints to GRIB conversion

  - Interpolate the BUFR 2m temperature values below the freezing
    point (one of the results of the previous exercise)
    into a 1 degree x 1 degree grid covering Scandinavia. Apply a
    proper contour shading for the visualisation and drop the
    gepoints data file into the Display Window.  

    Hints:	
      - use the Geopoints to GRIB icon 
      - use the following area:
       	  52.64/3.41/74.11/30.73 
       	       	  
    Comment: please note that if the output is set to Geopoints
             in the Observation Filter icon then you can use it
             as a Geopoints icon (e.g. you can drag it into an
             icon field that accepts Geopoints)
             
E3.4 GRIB to Geopoints conversion

  - Using the GRIB to Geopoints icon, generate a geopoints file from a
    GRIB file (try using the t_3day_fc icon). Note that only the first
    field will be converted because unlike GRIB, the geopoints format
    can only store a single field. Examine the result. 
    
    Comment: this is an easy way to convert a GRIB field into a list
             of coordinates and values.
  
  
E3.5 Derive 500/1000 relative topography in metres from
     zutv.grb for all the available dates.
   
    Hints: 
      - use the Simple Formula icon to compute the 500/1000
        relative topography (it is the difference between 
        500 hPa and 1000 hPa geopotential)
      - use another Simple Formula icon to convert the units to metres
        (geopotential is given in m2/s2 units instead of metres. You can get 
        metres after dividing the geopotential values by 9.81)
    
    Comment: you will see that it can be much more easily
            implemented in Metview Macro!


E3.6 Observation filtering

  - Extract 2m temperature values below the freezing point
    from BUFR.bufr

    Hints: 
      - use geopoints output
      - use custom filter
      - temperature values are given in K 

  - Extract the 10m wind vector for wind speeds larger than
    1 m/s form BUFR.bufr

    Hints: 
      - use geopoints polar vector output
      - BUFR parameters are 011012 (speed) and 011011 (direction)
      - use custom filter
