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Visual definition variables must appear just after the data variables to which they are to be applied. In fact, now that we have a shaded field covering the whole globe, there is no need to shade the land; we can remove coastlines from the plot() command. We will still see the coastlines, but Metview will use the default coastline definition, which is to draw the outline without shading the sea or the land.
Overlaying Another Field
We will now overlay our plot with fields of geopotential.
Copy the geopotential GRIB data file into your Metview directory (~/metview); if you are attending the training course at ECMWF, then you can instead type the following command in a terminal window:
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cp ~trx/mv_data/z500.grb ~/metview |
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Otherwise, download the file here XXXX. |
You should see the new GRIB icon in your Metview window.
Plot your temperature data by running your macro again, then drop z500.grb into the Display Window. The geopotential field appears as blue isolines (the default contouring style) over the shaded temperature field.
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:
| Contour Line Thickness | 2 |
| Contour Line Colour | Black |
| Contour Highlight | Off |
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.
Modifying a Default Icon
As an exercise, we will now make our set of coastline attributes the default in all Metview plots.
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| Info |
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| For information: To delete an icon, select is and press the Del button on the keyboard; alternatively, right-click, Move to wastebinwastebasket. Both will move the icon(s) to the wastebinwastebasket. The wastebin wastebasket can be emptied in order to permanently delete the icon(s). Standard shortcuts are available for copying, cutting and pasting icons icons. Alternatively, to move an icon between folders, drag it with the left mouse button; to copy an icon between folders, drag it with the middle mouse button. |
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Now visualise the data again - your new default coastline attributes are automatically applied.