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The GRIB data is already in its place. In your folder you will find the two GRIB files pl.grib (for pressure levels) and pl_surf.grib (for surface) you need to use for this exercise. Please note that both these files were retrieved from MARS.
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- pl.grib: contains z, t, r, u and v on pressure levels
- pl_surf.grib: contains z, 2t ,10u and 10v on surface
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Please note that both these files were retrieved from MARS |
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First, we retrieve our GRIB data from MARS. We will need two MARS retrieval icons: one for the surface and one for pressure levels.
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by using the 'ret_pl' and 'ret_pl_surf' |
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MARS retrieval icons in the solutions folder. |
Running Vapor Prepare
Create
| Type | FC |
| Param | z/2t/10u/10v |
| Level | sfc |
| Date | -1 |
| Time | 0 |
| Step | 0/12 |
| Area | 65/-10/35/30 |
| Grid | 1/1 |
| Type | FC |
| 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 |
| Area | 65/-10/35/30 |
| Grid | 1/1 |
Running Vapor Prepare
Having set up the retrievals we can focus on converting the data into the VAPOR format.
Now, create a VAPOR Prepare icon.
Rename it 'vapor_pl' and open up its editor.
First, we 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 Second, we define the list of GRIB parameters we you want to see in VAPOR.
| Vapor 2d Params | z/2t/10u/10v |
| Vapor 3d Params | t/u/v/r |
| Info |
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Internally VAPOR Prepare converts surface geopotential to metres and rename it HGT. |
Third, we set the 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 we you set the vertical grid type to 'Layered' and defined geopotential (z) as the parameter holding the elevation of the vertical layers (pressure levels). We You also specified the vertical coordinate range (in metres) that VAPOR will display.
| Info |
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Internally VAPOR Prepare converts geopotential to metres and rename it ELEVATION (this is required by VAPOR). |
Last, we 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 |
| Vapor Reuse Vdf | On |
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 iinto into a subdirectory called 'tut_pl_data'. By setting Vapor Reuse Vdf to 'On' we told VAPOR Prepare not to run the conversion if a VDF file already exits in the target location.
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.
To visualise the VAPOR data generated please follow the instructions here.
Model level data with elevation
This exercise demonstrate how to use model level ECMWF GRIB data with VAPOR when elevation available/can be derived. We will work with fields from yesterday's forecast on a the low resolution grid over Europe . The steps required are very similar to the previous exercise (with pressure levels) to only exception is the handling of geopotentialas we used for the pressure levels.
Getting the GRIB data
First, we retrieve our The GRIB data from MARS. We will need three MARS Retrieval icons: one for the surface, one for model levels and one for lnsp.
Now create a MARS Retrieval icon for the surface fields. Rename it 'ret_surf_ml', then apply the following settings:
| Type | FC |
| Param | z/2t/10u/10v |
| Level | sfc |
| Date | -1 |
| Time | 0 |
| Step | 0/12 |
| Area | 65/-10/35/30 |
| Grid | 1/1 |
Create another MARS Retrieval icon for the model level fields up to level 60. Rename it 'ret_ml' and edit it in the following way:
| Type | FC |
| Param | t/q/u/v/lnsp |
| Level | ml |
| Levelist | 137/to/60 |
| Date | -1 |
| Time | 0 |
| Step | 0/12 |
| Area | 65/-10/35/30 |
| Grid | 1/1 |
Create a third MARS Retrieval icon for lnsp on the bottommost model level. Rename it 'ret_ml_lnsp' and edit it in the following way:
| Type | FC |
| Param | lnsp |
| Level | ml |
| Levelist | 1 |
| Date | -1 |
| Time | 0 |
| Step | 0/12 |
| Area | 65/-10/35/30 |
| Grid | 1/1 |
is already in its place. In your folder you will find the three GRIB files you need to use for this exercise:
- ml.grib: contains q, t, u and v on model levels 137-60
- ml_lnsp.grib : contains lnsp on the bottommost model level (level 137)
- ml_surf.grib: contains z, 2t ,10u and 10v on surface).
Please note that both these files were retrieved from MARS by using the 'ret_ml', 'ret_ml_lnsp' and 'ret_ml_surf' MARS retrieval icons in the solutions folder.
| Info |
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Please note that upper level geopotential (z) is not available in the input files because it is not archived in MARS for model levels |
| Info |
Geopotential on model levels is not archived in MARS. However, VAPOR Prepare can derive it if tempreature (t), specific humidity (q) and logarithm of surface pressure (lnsp) are available. So we needed We has to ensure that these fields were present in the retrievalour data. |
Running Vapor Prepare
Having set up the retrievals we can focus on converting the data into the VAPOR format.
Now, create Create a VAPOR Prepare icon. Rename it 'vapor_ml' and open up its editor.
First, ensure that Vapor Input Mode is set to Icon then drop your three Mars Retrieval icons into the Vapor Input Data field.
Second, define the list of GRIB parameters you want to see in VAPOR.
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