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Rename it 'bin_grid_shade' then edit it, by setting the following parameters:
Legend | On |
Contour | Off |
Contour Level Selection Type | Count |
Contour Reference Level | 0. |
Contour Min Level | 1. |
Contour Shade Min Level | 1. |
Contour Level Count | 20 |
Contour Shade | On |
Contour Shade Technique | Grid Shading |
Contour Shade Method | Area Fill |
Contour Shade Max Level Colour | Red |
Contour Shade Min Level Colour | Blue |
Contour Shade Colour Direction | Clockwise |
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Now, if you execute this macro (right-click execute or click on the Play button in the Macro editor) you should see a Display Window popping up with this result (your plot might look different depending on your default symbol plotting settings):
Improving the Plot
In our plot the large increments (in terms of absolute value) are not clearly highlighted because the plot is dominated by the bright green colour assigned to the near-zero values. To enhance the plot we would like to apply another colour palette by using:
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mydb= read("AIREP.odb") |
We We perform two ODB/SQL queries for this database via the odb_filter command. The first query retrieves the u wind component while the second query retrieves the v wind component. As a result we have two ODB objects: filter_u containing columns lat, lon and u, and filter_v containing columns lat, lon and v. Since the u and v wind data come strictly after each other in the database we can be sure that the two ODBs have the same number of rows and their lat and lon columns are identical.
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In this exercise we will introduce how to retrieve ODB data from MARS in Metview.
| Note |
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Please note that the examples presented in this chapter are not guaranteed to work for you since the MARS ODB archive is still under development and subject to changes. |
The MARS Retrieval Icon
In Metview we can access ODB from MARS by using the standard MARS Retrieval icon. This icon is located in the Data Acces icon drawer.
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Now edit your MARS Retrieval icon so that it could perform this retrieval.
Please be aware that the Obsgroup parameter in the icon editor does not contain the string "hirs". Instead it offers a list of numerical IDs. The ID of HIRS is 2.
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- To examine: just right-click examine to look at its content.
- To visualise: you need to use an ODB Visualiser icon (see here). There is one, called 'plot_hirs', already prepared for you in the folder. It is to plot the observation values for channel 5 on a map. Just edit this icon and drop your MARS Retrieval icon into the ODB Data field. Save the icon (Apply) then right-click and visualise to generate the plot.
- To manipulate: you need to write a macro (please read the next section about how to do it).
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