Newly discovered series of meteorological measurements in SW Greenland (Nuuk) in the period 1806–13

Abstract. The article presents a description of a newly discovered, unique series of meteorological measurements in SW Greenland (Godthåb [now Nuuk]) from the beginning of the 19th century (1 November 1806 to 16 August 1813). The series is the longest available from before 1840, not only for Greenland but also for the entire Arctic. The handwritten meteorological register was discovered in the archives of the Royal Society in London (MA/154). The meteorological observations were carried out by the German mineralogist Dr Charles Lewis Giesecke. The observations include measurements, taken two to three times per day, of air temperature, atmospheric pressure and wind direction. In addition, the meteorological register briefly describes the weather conditions for each day. In the article, we present a detailed analysis of thermal conditions for the period covered by a complete series of measurements (Aug 1807–Jul 1813). The analysis of air temperature clearly shows that the study period was one of the coldest periods (possibly the coldest) in the past two millennia. A cooling of this severity has previously been found for the study region, the whole of Greenland and the whole Arctic. Among the available reconstructions that use different proxy data or that use climate models for this purpose, most of the reconstructions of air temperature are almost fully consistent with the available results of meteorological observations for this period. Intense volcanic activity and, to a lesser degree, the low solar activity connected with the Dalton minimum are most often given as reasons for the cooling of the early 19th century.