Air temperature changes in SW Greenland in the second half of the 18th century

• Main Authors: Przybylak, Rajmund, Singh, Garima, Wyszyński, Przemysław, Araźny, Andrzej, Chmist, Konrad
• Format: Text
• Language: English
• Published: 2023
• Subjects: Arctic; Greenland; Nuuk
• Online Access: https://doi.org/10.5194/cp-2023-95; https://cp.copernicus.org/preprints/cp-2023-95/

The thermal conditions of south-western Greenland in the second half of the 18th century were estimated using two unique series of meteorological observations. The first series (Neu-Herrnhut, 1st Sep 1767 to 22nd Jul 1768, hereinafter 1767–68) is the oldest long-term series of instrumental measurements of air temperature available for Greenland. The second (Godthaab, Sep 1784 to Jun 1792) contains the most significant and reliable data for Greenland for the study period. The quality controlled and corrected data were used to calculate daily, monthly, seasonal and yearly means. The daily means were further used to calculate day-to-day temperature variability (DDTV), thermal seasons, growing degree days (GDD), air thawing index (ATI), positive-degree days (PDD) and air-freezing-index-degree days (AFI). Air temperature in Godthaab (now Nuuk) was, on average, warmer than the present day (1991–2020) in 1767–68 and colder in 1784–92. Compared to the Early Twenty Century Arctic Warming (ETCAW) period, the data for the two sub-periods show that the late 18th century was as warm or even warmer. Except winter 1767/68, winters and springs in the study period were longer, while summers and autumns were shorter than at present. The analysed climate indices usually do not exceed the maximum and minimum values from 1991–2020. Mean daily air temperature in studied historical periods rarely exceed ±2 SD of the long-term mean calculated for the contemporary period. Their distribution was usually close to normal, both in historical and contemporary periods.