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.
Precision is the recognition that there might be systematic uncertainties in a measurement, which are irrelevant for long term trends as long as the instrumentation does not change. However, for climate records spanning multiple decades, it is expected that the instrumentation will change several times. In particular sounding equipment has gone through a rapid development in the last years and slowing down of this development is not expected. Therefore, the distinction between accuracy and precision has only limited use for long term climate records. A more suitable concept is a best estimate for the level of confidence in a measurement, which may simply be called uncertainty estimation.
Systematic errors have to be corrected. This means that studies are required to identify and quantify systematic biases. The solar radiation correction for the temperature measurement on radiosondes is a classic example for such a systematic bias that requires correction. Since no correction algorithm is perfect, this correction will then introduce a new and hopefully random uncertainty, which is then combined with all other sources of uncertainty.