The Reference Radiosonde as a Tool for Improving Meteorological Data from Conventional Radiosondes

The Weather Service of the Federal Republic of Germany, along with several other national services, has responded to an international call for development of reference radiosondes. Such devices make use of sensing methods with a high degree of precision which are superior to any conventional upper-air sensing system. Reference radiosondes serve in quality control of conventional upper-air data by means of in situ comparisons. At the Instrument Division München, substantial progress has been made towards the development of sensing systems of a suitably high degree of accuracy. Temperature will be measured by means of a 15 μ platinum wire of 100 ohms resistance, operated in connection with a Wheatstone bridge. To measure humidity, the dry bulb -wet bulb temperature spread will be determined from a pair of bead thermistors, one of which will be coated by a film of water or ice while the other has a dry coating thick enough to produce a match in time constant of the two beads at the ice phase. Pressure will be determined at 180 points as an aneroid cell constantly expends to inake successive electrical contacts with a micrometer which retreats incrementally after each contact; an essential feature is that the aneroid cell carries no load.