...
First start Metview; at ECMWF, the command to use is metview4_new metview (see Metview at ECMWF for details of Metview versions). You should see the main Metview desktop popping up.
...
and save it in your $HOME/metview directory. You should see it appear on your main Metview desktop, from where you can right-click on it, then choose execute to extract the files. You should now (after a few seconds) see a vapor_tutorial folder which contains the solutions and also some additional icons required by these exercises. You will work in the vapor_tutorial folder so open it up. You should see the following contents:
VAPOR Basics
VAPOR stands for Visualization and Analysis Platform for Ocean, Atmosphere, and Solar Researchers. It is a software system providing an interactive 3D visualization environment. The home of the software is https://www.vapor.ucar.edu.
...
- For layered grids VAPOR expects a parameter specifying the elevation of each 3D level in the input data. This is typically the case for pressure or model level (η levels) data with height or geopotential available (or it can be computed).
- For regular grids the 3D levels are supposed to be equidistant (in the user coordinate space). This type can be used when the data is available on equidistant hight height levels.
When pressure or model level data is present without height information the situation is somewhat special. The grid in this case is not layered but can be regarded as regular in its own coordinate space (pressure or model levels) letting the z axis simply represent pressure or model levels in the 3D scene rendered in VAPOR.
...
First, ensure that Vapor Input Mode is set to 'Icon' then drop the two Mars Retrieval icons into the Vapor Input Data field.
Then you need to define the list of GRIB parameters you want to see in VAPOR.
| Vapor 2d Params | z/2t/10u/10v |
| Vapor 3d Params | t/u/v/r |
| Info |
|---|
Internally VAPOR Prepare converts surface geopotential to metres and rename it HGT. |
The vertical coordinate system has to be set carefully:
| Vapor Vertical Grid Type | Layered |
| Vapor Elevation Param | z |
| Vapor Bottom Coordinate | 0 |
| Vapor Top Coordinate | 16000 |
Here you set the vertical grid type to 'Layered' and defined geopotential (z) as the parameter holding the elevation of the vertical layers (pressure levels). You also specified the vertical coordinate range (in metres) that VAPOR will display.
...
The last step is to specify the name and location of the results of the conversion:
| Vapor Vdf Name | tut_pl |
| Vapor Output Path | your_path_on_the_filesystem |
With these settings a VDF file called 'tut_pl.vdf' will be created in the directory you specified. All the other VAPOR data files will be placed into a subdirectory called 'tut_pl_data'.
...
First, ensure that Vapor Input Mode is set to Icon then drop your three Mars Retrieval icons into the Vapor Input Data field.
Then you need to define the list of GRIB parameters you want to see in VAPOR.
| Vapor 2d Params | z/2t/10u/10v |
| Vapor 3d Params | t/u/v/q |
The vertical coordinate system has to be set carefully:
| Vapor Vertical Grid Type | Layered |
| Vapor Elevation Param | z |
| Vapor Bottom Coordinate | 0 |
| Vapor Top Coordinate | 16000 |
Here you set the vertical grid type to layered and defined geopotential (z) as the parameter holding the elevation of the vertical layers (model levels). We also specified the vertical coordinate range (in metres) that VAPOR will display for this data.
...
Last, we specify the name and location of the results of the conversion:
| Vapor Vdf Name | tut_ml |
| Vapor Output Path | your_path_on_the_filesystem |
Now save your VAPOR Prepare icon then right click Execute to run the conversion. The icon will first turn orange then green when the conversion finishes.
...
Right click Visualise your VAPOR Prepare icon to start up VAPOR. You will see this window popping up:
Your vdf file (that you have created with your VAPOR Prepare icon) is now loaded into VAPOR and you can see a cube representing your 3D data volume.
...
If you rotate the cube in the display window (left mouse button) you will see it is flat. We need to scale the vertical axis to get a better view of the whole 3D volume. Go to the Edit → Edit Visualiser Features menu and set the Z Scene Stretch Factor to 200:
Now the full 3D volume is visible:
Setting up the map image
We can load a pre-installed map image to get a better geographical reference for the domain we are looking at. Open the Image tab and load 'BigBlueMarble.tiff' by using the Select Installed Image button. Then tick Instance: 1, tick Apply to Terrain and set Z to 0. The scene has now changed like this:
The VAPOR session file
...
Having set up the view you can now visualise our data. Click on the DVR (Direct Volume Rendering) tab, select Variable to relative humidity (r), tick Instance 1. Then change the opacity in the Transfer Function editor like this (drag the control points of the white curve and use the vertical slide on the right of the histogram):
Having done so you should get this scene:
Please note that this scene was generated by using only low resolution data. The see more details change the Refinement level first to 1 then to 2.
You should see more details appear in the scene:
Further rendering types
...