This icon derives (and returns) a vertical average cross sectional data unit of upper air fields. For each upper air field, 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 Hovmøller diagram data unit along a specified arbitrary transect line or a rectangular area. This application can be used to display a two-dimensional graph with latitude or height as one axis and time as the other. If an input line is given, point values for each field are interpolated along the transect line, with a spacing consistent with the resolution of the input GRIB data. If a rectangular area is given, average values for each field are taken along the North-South or East-West direction. The Hovmøller The average cross section data can be plotted (using a default visualisation and with the plot area based on the range of data values) or saved as a NetCDF data file. The option 'expand Hovmøller' allows the production of Hovmøller diagrams to be computed incrementally. This could be useful, for example, if the input data is too large or the Hovmoeller diagram needs to be updated periodically (e.g. to produce a diagram operationally during a certain period of time). A related icon, Hovmøller View is used to provide Hovmøller plotting specifications see "Hovmøller View" on page III- 145 and references therein. If access to the output computed values is not required, or for more control of the plotting, use the Average View icon. The macro language equivalents are hovmoeller_area(), hovmoeller_line(), hovmoeller_height() and hovmoeller_expand() (depending on the Hovmøller type you specify). The macro language equivalent is mxs_average(). |