This icon derives (and returns) a Thermodynamic diagram data unit. In such 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.

The Thermo data can be plotted (using default plotting specifications) or saved as a NetCDF data file. The input data are observations (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 Tephigram Data editor belongs to a type of editor known as family editor which allows related sets of input specifications to be grouped in the same icon editor, each in its own tabbed pane (like the Simple Formula icon - see Figure III-3 on page III-71). The available working input panes are :

Pm Bufr Tephi - Provides input for tephigrams based on observation (BUFR) data.

Pm Grib Tephi - Provides input for tephigrams based on model field (GRIB) data post 4th April 1995

Pm Pre19950404Grib Tephi - Provides input for tephigrams based on model field (GRIB) data pre 4th April 1995

The two varieties of GRIB data tephigrams exist due to changes in the attributes of the input data - parameter Q changed to Gaussian Grid from Spherical Harmonics.

To operate with this icon first you need to select which output you want to produce by clicking the tab of the corresponding pane.

Data

Drop any icon containing or returning BUFR data. This may be, for example, a MARS Retrieval (of observations) icon, a BUFR file icon or an Observation Filter icon (provided it outputs BUFR, not geopoints).

Output

Specifies the output format you want. Specify one of the geopoints formats (Geographical Points, Geographical Polar Vectors or Geographical X Y Vectors).

Parameter

To specify a parameter enter its unique BUFR descriptor value (a numerical code). Geographical Polar Vectors and Geographical X Y Vectors require two descriptors, separated by a slash (/). The descriptor value is of the form XXYYY, where XX defines the class (e.g. 12 = Temperature class) and YYY the parameter within that class (e.g. 12004 = Dry bulb Temperature at 2m). These descriptor values are different from the ones of the GRIB format. If you do not know the descriptor value, click-left on the assist button to obtain a check list of parameters and associated descriptors. This list only contains the most common parameters. If the one you need is not on the list you can use the BUFR Examiner (right-click, Examine the BUFR file) to see what is there, or up its descriptor value in the "BUFR Reference Manual" (available from http://www.ecmwf.int/products/data/software/bufr.html#description) - see "BUFR Table B", pages 6-19. The significance of code and flag values for non-quantitative parameters are given in the same manual, in "BUFR code table", pages 22-70.

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.