mhovmoeller_vertical

../../_images/MHOVMOELLERDATA.png

Generates a vertical Hovmoeller diagram data unit for a given geographical area for GRIB (Fieldset) input. The generated data can be used to display a two-dimensional graph with levels as one axis and time as the other.

The resulting 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 using write().

If access to the computed values is not required, or for more control of the plotting, use mhovmoellerview().

Note

See also mhovmoeller_area(), mhovmoeller_line() and mhovmoeller_expand().

Note

This function performs the same task as the Hovmoeller Data icon in Metview’s user interface. It accepts its parameters as keyword arguments, described below.

mhovmoeller_vertical(**kwargs)

Provides input for Hovemoeller diagrams derived at an input geographical location/area and on a set of levels.

Parameters

  • input_mode ({"point", "nearest_gridpoint", "area"}, default: "area") –

    Defines the horizontal data selection method:

    • ”point”: the data is interpolated to the location specified by point

    • ”nearest_gridpoint”: the nearest gridpoint to the location specified by point is extracted

    • ”area”: the values inside the area are averaged using integrate()

    New in Metview version 5.16.0

  • point (list[number], default: [0, 0]) – Specifies the coordinates (as [lat, lon]) of the point for which the vertical Hovmoeller is computed. Enabled when input_mode is “point” or “nearest_gridpoint”. New in Metview version 5.16.0

  • area (list[number], default: [30, -30, -30, 30]) – Specifies the coordinates of the area (as [north, west, south, east]) over which the Hovmoeller diagram is calculated. Enabled when input_mode is “area”.

  • area_statistics ({"mean", "minimum", "maximum", "stdev", "variance", "median"}, default: "mean") – Specifies the type of computation performed for the area. For “mean”, “stdev” or “variance” the aggregation is weighted by the cosine of the latitudes. Enabled when input_mode is “area”. New in Metview version 5.18.0

  • data (Fieldset) – Specifies the input GRIB data for the Hovmeller diagram. data must contain a time-series of a single meteorological variable on a latitude-longitude or Gaussian grid, on a set of vertical levels. If data is specified on ECMWF model levels and vertical_level_type is “pressure” data must also contain an Logarithm of Surface Pressure (LNSP) field (see lnsp_param) for each step, otherwise the pressure on the model levels cannot be computed.

  • vertical_level_type ({"as_in_data", "pressure", "user"}, default: "as_in_data") –

    Specifies the output vertical level type:

    • ”as_in_data”: the level type of data is used. In this case top_level and bottom_level must always be set carefully, since their default values are set for pressure in hPa.

    • ”pressure”: indicates that the data is defined on ECMWF model levels and the output vertical coordinate should be pressure in hPa. When this option is selected the input data must contain the corresponding Logarithm of Surface Pressure (LNSP) fields, unless a fixed surface pressure is used (see use_fixed_surface_pressure).

    • ”user”: the vertical coordinates (both input and output) are defined by the fields of vertical_coordinate_param. In this case top_level and bottom_level must always be set carefully, since their default values are set for pressure in hPa. New in Metview version 5.16.0

  • lnsp_param (number, default: 152) – Specifies the ecCodes paramId used to identify the Logarithm of Surface Pressure (LNSP) in the input data. Enabled when vertical_level_type is “pressure”.

  • use_fixed_surface_pressure ({"on", "off"}, default: "off") – When it is “on” a fixed surface pressure value will be used in the computations and no LNSP fields have to be specified. Enabled when vertical_level_type is “pressure”. New in Metview version 5.17.0

  • fixed_surface_pressure (number, default: 1013.25) – Specify the fixed surface pressure value in hPa when use_fixed_surface_pressure is “on”. New in Metview version 5.17.0

  • vertical_coordinate_param (number) – Specifies the ecCodes paramId used to identify the vertical coordinate fields in the input data. Enabled when vertical_level_type is “user”. New in Metview version 5.16.0

  • vertical_coordinate_extrapolate ({"on", "off"}, default: "off") – Performs an extrapolation for the top_level and bottom_level when the output vertical level range does not contain these levels. The purpose is to avoid blank areas in the plot near the bottom ot top. Only used when vertical_level_type is “pressure” or “user”. New in Metview version 5.16.0

  • vertical_coordinate_extrapolate_mode ({"constant", "linear"}, default: "constant") – Specifies the extrapolation technique. In “constant” mode the values on the nearest input levels are copied onto the target extrapolated levels. In “linear” mode a linear extrapolation is performed using the nearest two input levels. Enabled when vertical_coordinate_extrapolate is “on”. New in Metview version 5.16.0

  • vertical_coordinate_extrapolate_fixed_sign ({"on", "off"}, default: "on") – When vertical_coordinate_extrapolate_mode is “on” it controls whether the extrapolated values can differ in sign from the values on the nearest input levels. When it is “on” it prevents e.g. wind components to change sign due to extrapolation. New in Metview version 5.16.0

  • bottom_level (number, default: 1015.0) – Specifies the lower (closest to the surface) limit of the Hovmoeller data in the units of the vertical coordinates. Only levels in the range defined by top_level and bottom_level are included in the output data. An extra level on either side of this range is also added. Enabled when vertical_level_type is “pressure” or “param”.

  • top_level (number, default: 0.01) – Specifies the upper (furthest from the surface) limit of the Hovmoeller data in the units of the vertical coordinates. Only levels in the range defined by top_level and bottom_level are included in the output data. An extra level on either side of this range is also added. Enabled when vertical_level_type is “pressure” or “param”.

Return type

NetCDF