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The Cross Section View    

This The Cross Section View icon is a plotting specification for cross section plots along a given arbitrary transect line. 
Now

• create a new Cross Section View icon.
• Visualise it and drop the t_fc24.grib icon into the Display Window.

A default cross section along the Equator is generated. This is an alternative way to view your data - instead of a geographical plot for instance.

Inspect the GRIB icon (right-click on it and choose examine) to see the type of input data this View requires,

Edit the Cross Section View icon and change the To customise the transect line (coordinates along which the cross-section is calculated).- , do the following:

• Edit the Cross Section View icon
• change the transect line
  • click on the Geography Tool button to bring up an editor (or type the coordinate by hand).

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• Save/OK the changes and re-visualise the data with this new cross section.

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Note that you can still drag any valid Contouring icons you may have into the Display Window when visualising a cross section. For instance, apply the given shade icon. You may want to customise it and try different configurations.Notice that a Cross Section View icon editor contains a place for an embedded Thermo Grid icon, which configures the background attributes of the thermodynamic diagram.

The Vertical Profile View    

This The Vertical Profile View icon is a plotting specification for vertical profile plots.Create

• create a new Vertical Profile View icon.
• Visualise it and drop the t_fc24.grib icon into the Display Window.

The result This view shows a vertical profile at a point (or averaged over an area). Experiment with this icon in a similar way to how you did with the Cross Section View icon.

Icon The Graph Plotting icon is the visual definition used for the plotting of graphs (e.g. lines, curves and bar charts).    Image Added

To customise the line displayed in this plot,   do the following:

• create a new instance of

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• Graph Plotting and rename it to vdline.

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• edit it, setting the following parameters:

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• Save/OK the changes and drag it into the Display Window.

The Average View    

This The Average View icon is a plotting specification for average (zonal or meridional) cross-section plots.Create

• create a new Average View icon.
• Visualise it and drop the t_fc24.grib icon into the Display Window.

A default meridional average over the globe cross-section is generated. Experiment with this icon in a similar way to how you did with the Cross Section View icon.

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This will be covered in another session: Layout in Metview.

The Hovmøller View   

This The Hovmoeller View icon is a plotting specification for Hovmøller diagram plots along a specified arbitrary transect line or a rectangular area. The diagram displays a two-dimensional graph with latitude or height as one axis and time as the other.Create

• create a new Hovmoeller View icon.
• Visualise it and drop the t_ts.grib icon into the Display Window.

A default diagram derived from a transect line along the Equator is generated.

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Experiment with this icon by testing the above types and investigating other input parameters. Type Please note that type Vertical Hovm requires the following input GRIB data: t_ts_nlevels.grib. Examine and compare this GRIB data with the previous one.

As previously, you can use a Contouring icon to style the contours of the plotting.

The Thermo View   

This The Thermo View icon is a plotting specification for Thermodynamic diagram plots from a suitable GRIB or BUFR data source. In such a diagram, temperature, humidity (represented by the dew point) and wind values are displayed with respect to pressure.Create

• create a new Thermo View icon.
  
• Visualise it and drop the tquv_pl.grib icon into the Display Window.

A default diagram related to a geographical location [0,0] is generated.

Inspect Examine the GRIB icon (right-click on it and choose examine) to see the type of input data this View requires. Fields Temperature  and Specific Humidity are mandatory and they will be used to compute the Dew Point parameter. Fieldsets U and V wind components are optional, but if given they will be used to compute the wind vectors. If the data is given in model levels then a Logarithm of Surface Pressure field must be provided too in order to help the conversion to pressure levels fields.

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To customise the curves displayed in this plot,  you can apply (or edit it first) icon vdline. The changes will be applied to both lines. The ability to customise each line individually (temperature and dew point) will be available in the future release of Metview.

Icon The Wind Plotting icon is the visual definition responsible for specifying how gridded wind vector data is displayed. It controls features such as wind arrows and wind flags.    Image Added 

To customise the wind flags displayed in the plot, do the following:

• create a new instance of this icon and rename it to vdwind.
• Edit it, setting the following parameters:

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• Save/OK the changes and drag it into the Display Window.

 Macro example

To demonstrate the use of the View concept in a Macro language, let's create a program to analyse the vertical structure of temperature changes in time. This exercise reads two forecast steps, computes the differences and visualise the result in a cross section view.

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Now run the macro to generate the plot.

Also, inspect Examine the two input GRIB icons (right-click on it and choose examine) to analyse their contents,

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Metview uses a netCDF format internally for the results of some computations (this format will be covered at session: Data Part 2). In particular, most of the previous Views (i.e. Cross Section, Vertical Profile, Average, Hovmøller and Thermo) do this, but their result data is not available to the user. Therefore, each of these Views has a corresponding Data Module icon. If the intention is to simply plot the result, then the View icons are more useful. But to store the result data, the Data Module icon is required.Create both

• create a Vertical Profile View and a Vertical Profile Data

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• icons.
• Edit both to see the differences.

All the parameters related to the visualisation of the result are only in the View icon, and the Data parameter exists only in the Data Module icon.

Dealing Now dealing only with the Vertical Profile Data icon now, :

• drop the supplied input GRIB icon t_fc24.grib into the Data parameter box.

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• set the Point parameter to whatever you like and save the icon.

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• Examine this icon to see the resulting netCDF file in the NetCDF Examiner.

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• Save Result to save the result into a file for storage.

All of this can also be put into a Macro, where the resulting netCDF variable can be further manipulated before being written to a file (or visualised).:Write a short macro, named save_vp, which computes a vertical profile from the data (use the

• create a new Macro icon and rename it to save_vp.
• drop the Vertical Profile Data icon that you already set up

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• write the result to a file

. To write a netCDF variable to a file, the syntax is the same as for any other data type:

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Your macro should be 3 lines long (well, 3 commands anyway) - one to read the input GRIB file, one to compute the profile and one to write the result to disk

Extra work