A paper on the Meisei Temperature Reference (MTR) sonde (by K. Shimizu and F. Hasebe) has been submitted to the Atmospheric Measurement Technology journal and now is under the open review process (link).
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 following paragraphs from an e-mail by John Dykema describes how co-location and coincidence could be formalized. As an example, the measurements of a temperature profile by a sensor on a balloon and a profile retrieved from microwave radiometry are assumed.
Once we have two well-characterized sensors with rigorously assessed and validated uncertainties, then we can make robust recommendations on co-location.
A reference observations is an observation that gives the best estimate for the measurand as well as the best estimate for the level of confidence in this measurement. The best estimate for the measurand is nothing else than the measurement itself, the estimate for the level of confidence is described by the measurement uncertainty. Therefore, GRUAN will strive to establish uncertainty estimates for every measurement, which implies, that for a profile of an atmospheric parameter, GRUAN will attempt to establish the corresponding profile of the measurement uncertainty. The usefulness of any measurement will be determined by the size of the measurement uncertainty.
Please refer to the publication Immler et al., AMT, 2010 for more details.
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.
David Whiteman wrote:
I believe there is consensus that the measurements that cannot currently be made within the specifications of GCOS-112 using any technology include water vapor mixing ratio. Because of that, I believe it is important for this group to specify what intermediate measurement specifications might be useful for assessing climate change while work continues on developing sensors that can meet the GCOS-112 specification.