“…Nevertheless, the estimates presented in this paper, while being the most probable, and based on all the data available to the authors in digital form, can be significantly improved, if most of the entire former Soviet Union precipitation network (up to 11 thousand stations in the early 1970s), and/or the supplementary information about wind speed, precipitation type, and the history of the station exposures (to account for the wind undercatch) become available for the analyses. Figure 1, but after re-adjustment for wetting correction using Table AI and Table AII This study illustrates the challenges that proper data preprocessing represents for climate change studies and is part of a long list of similar difficulties, such as: the uncertainty with the bucket correction of sea surface temperature (Folland and Parker, 1995); troubles with implementation of the WMO recommendation in 1949 to switch the total cloud cover measurements from tenths to octas (some large countries, including Russia, Canada, China and the United States neglected this recommendation); introduction of new temperature sensors in the United States network (Quayle et al, 1991); and numerous changes in remote sensing instrumentation.…”