This tutorial explains how to convert ECMWF GRIB data into VAPOR format then and how to visualise the resulting data in VAPOR.
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In this exercise we will see how to use pressure level ECMWF GRIB data with VAPOR. We will work with fields from yesterday's forecast on a low resolution grid over Europe.
Retrieving the GRIB data
First, we need to retrieve our GRIB data from MARS. We need to create two MARS retrieval icons: one for the surface and one for the pressure levels.
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| Param | z/t/r/u/v |
| Level | pl |
| Levelist | 1000/950/925/900/850/800/700/600/500/400/300/250/200/150/100 |
| Date | -1 |
| Time | 0 |
| Step | 0/12/24 |
| Area | 35/-10/65/30 |
| Grid | 1/1 |
Setting up Vapor Prepare
Having set up the retrievals we can focus on converting the conversion of the data into the VAPOR format.
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First, we ensure that Vapor Input Mode is set to 'Icon' then drop the two Mars Retrieval icons into the Vapor Input Data field.
Second, we we define the list of GRIB parameters you we want to see in VAPOR.
| Vapor 2d Params | z/2t/10u/10v |
| Vapor 3d Params | t/u/v/r |
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We set the vertical grid type to 'Layered' and defined geopotential (z) as the parameter holding the elevation of the vertical layers (pressure levels). Internally, a VAPOR Prepare converts this parameter for geopotential to metres units and rename it ELEVATION (this is required by VAPOR). We also specified the vertical coordinate range (in metres) that VAPOR will display for this data.
Last, we specify specify the name and location of the results of the conversion:
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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 this directory into a subdirectory called 'tut_pl_data'. By setting Vapor Reuse Vdf to 'On' we told VAPOR Prepare not to run the conversion if there is a VDF file already exists exits in the target location.
Now save your ld VAPOR Prepare icon then right click Execute.
Running Vapor Prepare
Model level data
Retrieving the GRIB data
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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 this directory into a subdirectory called 'tut_pl_data'. By setting Vapor Reuse Vdf to On we told VAPOR Prepare not to run the conversion if there is a VDF file already exists in the target location.
Now save your ld VAPOR Prepare icon.
Running Vapor Prepare
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