This icon derives (and returns) a vertical average cross section sectional 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, this average is taken along the North-South or East-West direction over a specified rectangular area and then interpolated horizontally along the direction perpendicular to the averaging direction with a spacing consistent with the resolution of the input GRIB data. The average cross section data can be plotted or saved as a NetCDF data file (which gets a specific icon of course). A related icon, Cross Section Average View is used to provide average cross section plotting specifications. You can use it to visualise a an average cross-section without explicitly deriving the average cross-section data - see The View Concept in Visualisationsee "Average View" on page III- 139 and references therein. The macro language equivalent is mcrossxs_ sectaverage() . | 