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When you first start Metview, you will see something like this:

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This sort of window is called a Metview desktop.is called a Metview desktop.

To get started, copy a GRIB data file into your Metview directory (~/metview); if you are attending the training course at ECMWF, then you should carefully type the following command in a terminal window:

 cp ~trx/mv_data/t1000.grb $HOME/metview/training/day_1

You If you navigate Metview to the training/day_1 you should now see a new GRIB icon in your Metview window:

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If it does not appear immediately, press F5 (or View | Reload) F5 (or View | Reload).

Move the icon into the folder 'a quick tour' by dragging and dropping it there. Enter the folder and do this exercise there.

When you right-click on an icon, a context-sensitive menu appears.

Choose examine to quickly see the structure of the GRIB file.

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The Magnifier button in the toolbar toggles the magnifier tool on and off. Unlike Zoom, this is a purely graphical enlargement of the plot. It is usedmainly used mainly to inspect small text such as contour labels. The magnifying glass can be moved and resized using the mouse, and the magnification scale on its left-hand side can also be adjusted.

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We will investigate these features in more detail later, but for now close the Display Window.

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Creating and Editing an Icon

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Let’s customise the coastline plotting attributes.

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Edit the newly-created icon by either double-clicking on it or else right-click, edit (double-clicking an icon performs the edit action for most icon types). This brings up the icon editor for coastline plotting. All user-selectable parameters for plotting coastlines are here. Set the following parameters:

For colour-based parameters, there are two small arrows - the one on the right reveals a drop-down list of predefined colours (use this one); then one on the left reveals an advanced colour selection tool.

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Visualise the data again, and drag your new Coastlines icon into the Display Window.

Your Coastlines icon can be dragged into any plot, and later we’ll see how to store useful icons so that they can be easily accessed from anywhere.

So you know what it does, rename the icon to land_shade by clicking on its name and editing the text.Image Removedrename the icon to land_shade by clicking on its name and editing the text.

Changing the Map Projection and Storing the Area

Metview's default map projection is Cylindrical. However, meteorologists often use other projections when plotting data.

Create a new Geographic Geographical View icon and rename it to polar_europe. Edit the icon and change the following parameter:

Save the changes and visualise the icon. Drop the GRIB data icon into the Display Window to see it on the new map. It is also possible to visualise the GRIB icon and then drop the Geographic Geographical View icon into the plot to achieve the same effect. Have a look at some of the other projections on offer, then go back to polar stereographic.

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Use the Zoom tools to enlarge the European area and use the Area tool to select a region over Europe. Click Ok to save your selection - your choices will now be updated in the Geographic Geographical View editor. Click Apply in the Geographical View editor to save everything. Plot your data in this view to confirm that the area and projection are as desired.

Linking the Coastlines icon with the

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Geographical View Icon

Although they can be used separately, the Coastlines icon can be linked into the Geographic Geographical View icon through the concept of embedded icons.

Notice that a Geographical View icon editor contains a place for an embedded Coastlines icon. If you drop a Coastlines Coastlines icon here and apply the changes, then the Geographical View icon will use your chosen coastlines.

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Metview incorporates a powerful Macro language, which can be used for tasks ranging from simple automation of tasks to complex post-processing of data. We will now create a simple macro which reads the GRIB file and plots it in our chosen projection.

Create a new Macro icon and edit it. This time we see a code editor, custom-built for the Macro language. The editor can automatically translate Metview icons into Macro code, so do the following:

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# Metview Macro

t1000 = read("/path/to/user/metview/training/day_1/metviewa quick tour/t1000.grb")

land_shade = mcoast(
    map_coastline_thickness         : 2,
    map_coastline_land_shade        : "on",
    map_coastline_land_shade_colour : "cream"
    )

polar_europe = geoview(
    map_projection      : "polar_stereographic",
    map_area_definition : "corners",
    area                : [30,-25,50,65],
    coastlines          : land_shade
    )

plot(polar_europe, t1000)

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Metview provides many ways to style the contours when plotting data. These are controlled via the Contouring icon. This is another visdef icon. Create a new instance of this icon and rename it to shade. Edit it, setting the following parameters:

Apply the changes, visualise the data icon again (t1000.grb) and drag the shade icon into the Display Window.

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Create a legend by changing the first parameter in the Contour editor and dragging the icon into the Display Window again:

Fixing the Contour Levels

Now zoom in and out of different areas. What happens to the palette - does it stay constant? The default behaviour is to create contours at 10 levels within the range of data actually plotted. As the area changes, so does the range of values being plotted.
Let's create a palette which will not be altered when we change the area. Copy the shade icon (either right-click + duplicate, or drag with the middle mouse button), and rename the copy 'fixed_t' by clicking on its title. Edit the icon and make the following changes:

Now when you apply this icon you will see that the palette is fixed wherever you zoom. There will probably be parts of the plot which are not filled; this is because our range of contour levels does not cover the whole range of values in the data. Change the list of contour levels so that the whole plot will be covered - you only need to add one number to each end of the level list to do this (or else change the current numbers at the ends of the list).

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You should see the new GRIB icon in your Metview working day_1 folder. Move this icon into the folder you are working in.

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We will now change these isolines to black. Create a new Contouring icon and rename it to black_contour. Edit it and set the following:

Drop this into the Display Window - the result is not as intended! The new Contouring definition was applied to both fields, not just the geopotential. Close the Display Window and re-run the macro to get us back to the point before we added the geopotential. This time, select both the z500.grb and black_contour icons and drop them together into the Display Window. This forces the association between the data and the visual definition. You might want to remove the temperature isolines by setting Contour to Off in the macro.

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Spend some time exploring the Contouring icon. Here are some suggestions:

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Spend some time exploring the Coastlines icon. Here are some suggestions:

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