Import Radiosonde Files

The temperature and humidity profile display menus offer a feature for loading radiosonde data files to directly compare with the radiometer data (Import RS Data). When a radiosonde file is loaded and the RS display toggle button shows Display RS Data, the radiosonde data is displayed in red as an additional plot when a profile is selected.
By clicking the Import RS Data button in a profile map window, one enters the Radiosonde File Format sub-menu in Fig.19a. Radiosonde data files (usually available in ASCII) come in a variety of different file formats. 
Usually the file starts with a header containing information about the station (e.g. station number) and a definition of the data columns and their units. The data is listed in columns separated by blanks, commas etc. 
Before loading such a file, one has to define in which columns the program can find the three important data types Altitude, Temperature and Humidity. The user may set the right column numbers in the Radiosonde File Format menu.
Available altitude units are m, km, hPa and Pa. Sometimes the altitude is not stored in m or km but as the barometric pressure (e.g. mbar or hPa or Pa).
Units for the temperature are °C, K, F or °C*10. The last unit is sometimes used to keep the column data format as an integer number (e.g. 12.3°C is written as 123).
Units for relative humidity are %, 0-1 or Dpt (dew point). The most common unit is % but rel. humidity is sometimes expressed by a number between 0 and 1.A less frequent unit is Dpt (dewpoint, expressed in the same unit as for the temperature column) and the rel. humidity has to be computed from that number and the temperature reading.
Furthermore there are radiosonde file formats with reversed order, meaning that the highest altitude sample is listed first. In this case one has to check the Reverse Order checkbox.
For ground level correction it is useful to define the radiosonde station altitude (Station Alt.) and radiometer altitude (Radio. Alt.).
All settings can be stored in a database (file RS.FMT in the home directory) by clicking Add to Database; but do not forget to define an entry name first. Each entry is listed in the Current Entry list box and can be deleted from the database with Delete from Database.
Once all parameters for the file definition are entered, the radiosonde file can be loaded with Load RS File.