This icon derives (and returns) a vertical cross section data unit of upper air fields along a specified arbitrary transect line. For each upper air field, point values are interpolated along the transect line, with a spacing consistent with the resolution of the input GRIB data.
The cross section data can be plotted or saved as a NetCDF data file.
A related icon, Cross Section View is used to provide cross section plotting specifications. You can use it to visualise a cross-section without explicitly deriving the cross-section data - see The View Concept in Visualisation.
The macro language equivalent is mcross_sect().
The Cross Section Data Editor
Data
Specifies the data (GRIB icon) from which to derive the cross-section profile. The input GRIB icon must specify a multi-level (pressure or model levels) upper air meteorological variable, in a latitude-longitude or Gaussian grid. If the input data is specified in model levels, you must include the parameter LNSP should you want the vertical axis of the plot in pressure levels rather than model levels when visualising the output.
Interpolate Values
Specifies whether to interpolate vertically the cross-section values into a regular set of interpolated vertical levels. Choosing not to interpolate returns a cross section data matrix with values at the original levels.
Note - if you need to use the cross section data in calculations further down the stream you should not interpolate.
Line
Missing Data
If set to Ignore, missing data is not included in the output file; this is the default behaviour. If set to Include, missing data will be output to the geopoints file, its value being set to that specified by Missing Data Value. Note that when the output format is one of the two geopoints vector formats, the observation is considered missing if one or both of the parameters are missing.