Attached is a document describing the requirements for GRUAN station regarding the pre-launch procedures for routine soundings with Vaisala RS92 radiosondes. In order to obtain high data quality, ensure long term stability, and to make sure that measurement uncertainties are within the ranges that are reported in the product files, it is important that some ground checks are made before launch in the way described in this document and that the meta-data are reported to the GRUAN lead centre.
The paper “A guide for upper-air reference measurements” by F. Immler, J. Dykema, T. Gardiner, D. N. Whiteman, P. W. Thorne, and H. Vömel went online on the interactive Journal “Atmospheric Measurement Techniques” where it is open for public discussion for eight weeks (link).
The Accurate Temperature Measuring (ATM) radiosonde is one instrument to quantify the solar radiation error of the temperature measurement. The use of such an instrument is highly encouraged and may be used with additional surface measurements aimed at quantifying the radiation error of different temperature sensors. Uncertainty estimates should be provided for this type of instrument as well and may require additional research. This research will strongly contribute to minimising radiation related uncertainties of temperature measurements. The lead centre may coordinate such efforts.
Franz Immler wrote:
During the Lindenberg meeting it was agreed that among other things GRUAN station were required to conduct
1 x weekly production radiosonde with the best technology currently available (GCOS-121)
this suggestion has already often been argued about and is certainly one of the weaker points in the current concept of GRUAN. It obviously refers to an commercially available standard radiosonde which is currently launched at most sites 2 or even 4 times a day anyway. Even though some plans referring to extended ground check and alike are being discussed, it is currently not clear what should be the benefit of the additional launch of such an instrument.
What I suggest therefore, is to launch (at least) once a week two different high quality radiosondes on one balloon. Every GRUAN station can select one additional type of radiosonde to what they regularly start anyway and conduct a parallel launch of the two radiosondes once a week, better twice a week, one day and one night time. In principal every station can choose any radisonde they like but it is recommended to seek guidance from the lead centre.