The SCM Interface in Metview - Tutorial

What does Metview offer for SCM users?

In Metview users can:

• examine and edit (modify) an input netCDF file
• define a namelist file for SCM
• run SCM using a given executable, input netCDF file and namelist
• having run SCM Metview concatenates the three output netCDF files into one netCDF file. Users can specify the name and location of this file
• run a Metview macro which offers different ways to visualise the output data and compare runs.

In the following chapters we give details about the icons that make up the Metview SCM interface and also show how to use them.

Start Metview

To access the SCM interface metview4_dev has to be used. It can be started up by typing

metview4_dev

in the command line.

Copy the tutorial files

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Now your 'scm' folder should contain two icons:

The SCM Input Data icon

Your input SCM data file is recognised as a distinct filetype in Metview (by checking if the dataID global attribute is set to  "SCM_OUTPUT") and this icon is assigned to it:

Right-click this icon and select examine from the context menu. Metview's own netCDF examiner is started up showing the metadata content of the file.

Now close the netCDF examiner and right-click the icon and select edit from the menu. The SCM data editor is popping up.

This bespoke editor allows examining and modifying the data stored in the file.

The editor's window is split into two parts:

• the left hand side shows the data in a table view (one column represent a given profile)
• the right hand side displays the selected profile as a curve. There is a level range selector to the right of the curve plot. By dragging or resizing the orange rectangle the actual level range can be set arbitrarily.

There are a set of model-level variables defined to be editable and their columns are highlighted in a brighter shade of beige. The editable variables are as follows:u, v, t, q.

Editing can be done by typing a new value in a table cell or by dragging the points of the curve. These actions are synchronised: any modification in the table view will be immediately reflected in the curve, and vice versa. Modified data values are highlighted in deep orange.

Having finished the modifications the data can be saved back to the netCDF file by clicking on the Ok button.

Namelists

Your namelist file is recognised as a distinct filetype in Metview and this icon is assigned to it:

Double-click or right-click edit the namelist to see or change its content using Metview's own text editor.

The SCM Run Icon

You can run the SCM in Metview by using the SCM Run icon:

To create a new SCM run icon, drag a copy of it from the Modules (Data) icon drawer at the bottom of the Metview desktop. (Alternatively, right-click in the Metview desktop and select 'New icon'. This will bring up the icon selection list where you can find the SCM Run icon towards the bottom. Now click on it and wait until the newly created icon appears in your folder.)

The SCM run icon enables you to:

• define the path to the SCM executable. If this path is not defined Metview tries to use the path defined by the MV_SCM_EXE env variable.

• define the namelist for the SCM run

• define the vtable file for the SCM run (you can leave this field blank, Metview will use the files from /vol/rdx_dir/scm/vtables) 

• define the way the output data is treated. The output is always one netCDF file that Metview creates out of the three output netCDF files generated by the SCM.
  
  • If SCM_COPY_OUTPUT_DATA is set to 'ON' Metview will copy the output file to the location specified by SCM_OUTPUT_DATA_PATH. If this path contains only a filename the result will be placed into the current folder.
  • If SCM_COPY_OUTPUT_DATA is set to 'OFF' the output file is kept in a temporary directory and can be accessed only via the icon interface (using the save or examine actions).

Now double-click or right-click edit your SCM Run icon to open up its editor.

First, specify the path to your SCM executable via parameter SCM_EXE_PATH (do not forget to hit ENTER after typed in the path, this guarantees that the text will be saved when click Apply in the editor).

Second, drop your input data icon icon into the SCM_INPUT_DATA_PATH field and your namelist into the SCM_NAMELIST fields, respectively.

Third, set the output location if you want to work with a copy of of your SCM output data. 

Finally, save your changes (by clicking Apply in the editor) then right click and execute the icon to start your SCM integration. The icon label turns orange indicating that the computations have started. Having finished the integration the icon label turns green showing that no errors occurred (on error the icon label turns red).

If any errors or warning were generated these will be available in the icons output window. This window always show the location of the STDOUT and the fort.20 file generated during the SCM run.

Visualising the SCM data

The output of an SCM run can be visualised using the SCM Visualiser icon, located in the Modules (Plotting) icon drawer or else available from the right-click desktop menu: 

This icon allows the generation of the following plot types (specified in the Scm Plot Type parameter) :

	Time Height Matrix	Time Value Curve	Profile
Single data file
Overlay with second data file

Create a new SCM Visualiser icon and edit it. Drop your SCM Run icon into the Scm Data parameter box in the SCM Visualiser icon editor.

Set the following parameters:

Apply (save) the icon and right-click | Visualise it to get an on-screen plot.

To compare your two runs, set Scm Compare Data to On and drop your SCM Run 2 icon into the Scm Comparison Data icon box. Apply, then visualise.

To generate a different plot, but keep these settings, make a copy of your Scm Visualiser icon and edit this copy.

Try the following settings to obtain a matrix plot:

To obtain a set of profiles, try these settings:

The Scm Times parameter specifies the time slices to use (specified in minutes).

The other way of visualising the differences between two runs is to set Scm Comparison Mode to Difference.