ИСТИНА

Regarding current climate changes, an important task is to receive more full and accurate data about the air temperature T during whole the history of instrumental measurements, including the earliest data at the end of Little Ice Age. In Moscow episodic meteorological measurements were started in 1731 and the regular ones – in 1779 when a station of Mannheim network was founded there. All available data of this station in 1779– 1792 were collected from issues of Ephemerides Sosietatis Meteorologicae Palatinae. Some methodical questions (unknown location of this station, unknown conditions of thermometer shading, installation and height, accuracy of calibration, etc.) were analyzed. As a result it was found that the most probable error due to thermometer installation close to the northern building wall is ±0.1÷0.2 ºС; the error of mean daily T due to unknown height of measurements is ±0.1 ºС; the calibration accuracy in Mannheim was about ±0.1 ºС. Thus, total error of T on average of a day in the 18th century was not higher than ±0.3÷0.4 ºС. Probably it was less because separate components of the error may be multydirectional. For the first time mean-annual T was received for 1783, and the most probable values were estimated for 1784 and 1785 using the data of the closest station in Saint-Petersbourg for separate months with data gaps. Minimal T in December, 1788 was –38.8 ˚С. Later measurements in Moscow were renewed since 1808. For the first time unknown data of everyday measurements which were made by I.Lange in 1816–1817 were found and studied. As is known the famous 1816 ‘Year Without a Summer’ was noted all over the World by extremely cold summer as a result of Mount Tambora eruption. Nevertheless, it was found that summer of 1816 in Moscow was comparatively cool but not extremely cold: monthly-averaged T there was 15.7, 17.3 and 14.5 ˚С in June, July and August, respectively, and 15.8 ˚С on average of whole the season. Thus, 1816 occupies only 27th place among the coldest summers in the city during 213 years. Author is thankful to the memory of his late PhD student E.L.Vasilenko. This work was supported by the Russian Science Foundation (No.16-17-10275).