This icon derives (and returns) a Thermodynamic diagram data unit. In such a diagram, temperature, humidity (represented by the dew point) and wind values are displayed with respect to pressure. There are mainly four different types of thermodynamic diagrams: Tephigram, Skew-T, Emagram and Stuve, but only the Tephigram diagram is currently implemented in Metview.
The Thermo Data icon can be plotted (using default plotting specifications) or saved as a NetCDF data file. The input data types are observation (upper air BUFR) or model field (GRIB) data.
The macro language equivalents are thermo_bufr() and thermo_grib() (depending on the specified data type).
The Thermo Data Editor
The Thermo Data editor allows two modes of input:
- Bufr Thermo - provides input for thermodynamic diagrams based on observation (BUFR) data.
- Grib Thermo - provides input for thermodynamic diagrams based on model field (GRIB) data.
Data (Bufr Thermo)
Specifies the data to be used in the plotting of a thermodynamic diagram from observations data. The icon field assist button provides a tailor made MARS request to help with the data specification. The data should be upper air sounding data (VSNS - Vertical Sounding Non-Satellite ). Please note that PILOT observations (winds only) do not have enough data for plotting a thermodynamic diagram.
Data (Grib Thermo)
Specifies the data to be used in the plotting of a thermodynamic diagram from model field data. The icon field assist button provides a tailor made MARS request to help with the data specification. The data should include gridded model fields of Temperature and Specific Humidity. These parameters must have the same number of levels and they will be used to compute the Dew Point parameter. Fieldsets U and V wind components are optional, but if given they will be used to compute the wind vectors data unit. These two components must have the same number of levels, but not necessarily have the same number of levels of Temperature and Specific Humidity. If the data is given in model levels then a Logarithm of Surface Pressure field must be provided too. The data can be provided as a single GRIB file or as multiple GRIB files.
Point Selection
Specifies how the geographical location, for which the diagram is to be plotted, will be selected. Options are: Coordinates, Area Average and Station.
Coordinates
Specifies the latitude/longitude location for which the diagram is to be plotted.
Area Average
Specifies a geographical area (lat1/lon1/lat2/lon2) over which an area average value will be used, instead of a point value, to produce the diagram.
Station
Specifies the location for which the diagram is to be plotted. In the Bufr Thermo dialogue, this must define a meteorological station that provides full upper air soundings. In the Grib Thermo dialogue, this may represent any arbitrary geographical point.
Point Extraction
Specifies the way to calculate values at the point location for GRIB thermodynamic diagrams. Options are:
- Interpolate - interpolate values from the surrounding grid points (default)
- Nearest - using the data of the nearest grid point
Dew Point Formulation
Specifies the equation to compute the Dew Point parameter. Options are: "Saturation Over Water" and "Mixed Phase 0 to -23".
Temperature Param
Specifies the parameter number of the temperature, if the data is a non-ECMWF. ECMWF uses specific parameter numbers different from the WMO ones.
Specific Humidity Param
Specifies the parameter number of the specific humidity, if the data is a non-ECMWF. ECMWF uses specific parameter numbers different from the WMO ones.
Lnsp Param
Specifies the parameter number of the Lnsp, if the data is a non-ECMWF. ECMWF uses specific parameter numbers different from the WMO ones.
U Wind Param
Specifies the parameter number of the U wind component, if the data is a non-ECMWF. ECMWF uses specific parameter numbers different from the WMO ones.
V Wind Param
Specifies the parameter number of the V wind component, if the data is a non-ECMWF. ECMWF uses specific parameter numbers different from the WMO ones.