This icon generates the gridded input data and the AVAILABLE file needed to run the FLEXTRA trajectory model. The input forecast or analysis fields are automatically retrieved from ECMWF's MARS archive.

The macro language equivalent is flextra_prepare().

About FLEXTRA input  data

FLEXTRA requires input fields on a regular latitude-longitude grid in GRIB format. The input data must contain four three-dimensional fields: the two horizontal wind components, vertical velocity and temperature. Two additional two-dimensional fields are needed as well: topography and surface pressure. The three-dimensional input data has to be available on ECMWF model (i.e. η) levels defined by a hybrid vertical coordinate system. An important restriction is that all the data fields used within a FLEXTRA run must have the same domain size, resolution, number of levels, etc.

All the required fields, with one exception, can be retrieved from ECMWF's MARS archive. The only exception is vertical velocity because FLEXTRA needs the following field for its computations:

 

\dot \eta \frac{\partial \eta}{\partial p}
 

Since only

 

\dot \eta
 

is archived in MARS the full product needs to be computed during the data preparation process (FLEXTRA Prepare does it for you).

FLEXTRA requires all the input GRIB files to be in the same folder using the following file naming convention: ENyymmddhh. In addition to the GRIBs FLEXTRA needs several parameter files as well. Most of these files are automatically generated by Metview in the background, so users do not need to create them. The only exception is the file called AVAILABLE because it can be optionally provided by the user.

 

All the date parameters used for FLEXTRA Prepare has yyyymmdd format. Relative dates are allowed to use: e.g. -1 means yesterday, 0 means today etc.                   

The VAPOR Prepare Editor

Vapor Input Mode

Specifies the data input mode. The possible values are: Icon and Path. The default value is Icon.

In Icon mode a set of GRIB icons has to be specified in Vapor Input Data. If the mode is set to Path the input data is read from a specified path on the filesystem  (yet to be implemented).

Vapor Input Data

Specifies the input data as a set of GRIB icons. It is available when Vapor Input Mode is Icon.

Vapor 2d Params

Specifies the list of 2D parameters from the input data to be converted into VAPOR format. The parameters are identified by their short names. The default value is an empty string. 

Vapor 3d Params

Specifies the list of 3D parameters from the input data to be converted into VAPOR format. The parameters are identified by their short names. The default value is an empty string.

Vapor Vertical Grid Type

Specifies the type of the 3D data to be used in VAPOR. The possible values are: Layered and Regular. The default value is Layered.

If the type is set to Layered 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) input data.

For the Regular type the

Vapor Elevation Param

Specifies the short name of the 3D parameter interpreted as the elevation of the 3D levels. Available when Vapor Vertical Grid Type is Layered.

This parameter has to be either the height or the geopotential (z) of the levels. If geopotential is specified it is converted into metres by Metview for Vapor. The default value is z.

Please note that neither the height nor the geopotential of model levels are archived in MARS. It means that for model level data either of these fields has to be computed for Layered mode. These computations can be done internally in VAPOR Prepare by simply specifying z for Vapor Elevation Param. The computations can only be done if the input data contains temperature (t) and specific humidity (q) on model levels and geopotential (z) and logarithmic of surface pressure (lnsp) on the bottommost model level.

Vapor Bottom Coordinate

The name of the upper level GRIB parameter interpreted as the elevation of the upper levels. Available when Vapor Vertical Grid Type is Layered.

Vapor Top Coordinate

The name of the upper level GRIB parameter interpreted as the elevation of the upper levels. Available when Vapor Vertical Grid Type is Layered.

Vapor Area Selection

Specifies the data input mode. The possible values are: Native and Interpolate. The default value is Native.

If it is set to Native


The name of the upper level GRIB parameter interpreted as the elevation of the upper levels. Available when Vapor Vertical Grid Type is Layered.

Vapor Area

Specifies the area of the output grid in south/west/north/east format. The default value is  -90/-180/90/180. Available when Vapor Area Selection is Interpolate.

Vapor Grid

Specifies the resolution of the output grid in dx/dy format, where dx is the grid increment in east-west direction, while dy is the grid increment in north-south direction (both in degrees units). The default value is: 1/1. Available when Vapor Area Selection is Interpolate.

Vapor Refinement Level

Specifies the resolution of the output grid in dx/dy format, where dx is the grid increment in east-west direction, while dy is the grid increment in north-south direction (both in degrees units). The default value is: 1/1.

Vapor Vdf Name

Specifies the resolution of the output grid in dx/dy format, where dx is the grid increment in east-west direction, while dy is the grid increment in north-south direction (both in degrees units). The default value is: 1/1.

Vapor Output Path

Specifies the output directory (it has to be an absolute path) where the GRIB files and the AVAILABLE file will be generated. If this directory does not exist Metview will create it. The output GRIB files have the following naming convention: ENyymmddhh.

Vapor Reuse Input

If this parameter is set On FLEXTRA Prepare checks the existence of the data files to be generated and if they are already in place no new data is retrieved and processed. If it is Off all the fields are always retrieved and processed and the existing data files are overwritten. The same happens to the AVAILABLE file. The existence of a FLEXTRA input GRIB file is checked by using the file name and a set of GRIB API keys from the first message in the file. These keys are as follows: date, time, stepRange, gridType, iDirectionIncrement, jDirectionIncrement, latitudeOfFirstGridPoint, latitudeOfLastGridPoint, longitudeOfFirstGridPoint, longitudeOfLastGridPoint.





Flextra An Mars Expver

The MARS experiment identifier of the analysis fields. The default value is 1 (operational analysis). 

Flextra Date

Specifies the run date of the forecast. Available when Flextra Prepare Mode is Forecast.

Flextra Time

Specifies the run time of the forecast . Available when Flextra Prepare Mode is Forecast.

Flextra Steps

Specifies the forecast steps in hours. Here a list of values is given. Available when Flextra Prepare Mode is Forecast.

Flextra Period Start Date

Specifies the start date of the period. Available when Flextra Prepare Mode is Period.

Flextra Period Start Time

Specifies the start time of the period. Available when Flextra Prepare Mode is Period.

Flextra Period End Date

Specifies the end date of the period. Available when Flextra Prepare Mode is Period.

Flextra Period End Time

Specifies the end time of the period. Available when Flextra Prepare Mode is Period.

Flextra Period Step

Specifies the time step of the period in hours. The allowed values are as follows: 3 or 6. Available when Flextra Prepare Mode is Period.

Flextra Area

Specifies the area of the output grid in south/west/north/east format. The default value is  -90/-180/90/180.

Flextra Grid

Specifies the resolution of the output grid in dx/dy format, where dx is the grid increment in east-west direction, while dy is the grid increment in north-south direction (both in degrees units). The default value is: 1/1.

Flextra Top Level

Only data on and below this model level will be used to generate the FLEXTRA input fields. This level can be specified either as a model level or as a pressure value. In the latter case FLEXTRA Prepare will use the data retrieved for the first date to determine the topmost model level. The default value of this parameter is 1, which mens that all the model levels will be used if Flextra Top Level Units is set to Model Levels.

Flextra Top Level Units

Specifies the units of the value of Flextra Top Level. The allowed values are Model Levels or hPa. The default value is Model Levels. 

Flextra Reuse Input

If this parameter is set On FLEXTRA Prepare checks the existence of the data files to be generated and if they are already in place no new data is retrieved and processed. If it is Off all the fields are always retrieved and processed and the existing data files are overwritten. The same happens to the AVAILABLE file. The existence of a FLEXTRA input GRIB file is checked by using the file name and a set of GRIB API keys from the first message in the file. These keys are as follows: date, time, stepRange, gridType, iDirectionIncrement, jDirectionIncrement, latitudeOfFirstGridPoint, latitudeOfLastGridPoint, longitudeOfFirstGridPoint, longitudeOfLastGridPoint.

Flextra Output Path

Specifies the output directory (it has to be an absolute path) where the GRIB files and the AVAILABLE file will be generated. If this directory does not exist Metview will create it. The output GRIB files have the following naming convention: ENyymmddhh.

Vapor Bottom Coordinate

The name of the upper level GRIB parameter interpreted as the elevation of the upper levels. Available when Vapor Vertical Grid Type is Layered.