DOI: 10.18150/podxzq
title: Subdaily records of atmospheric pressure, wind speed and direction, and air temperature in Labrador in the second half of the 18th century

description: The earliest meteorological data for the northeastern coast of the Labrador Peninsula date back to the second half of the 18th century. Weather observations were conducted by the Moravian Church who settled here in 1771 to establish the first Christian mission in a settlement called Nain.Within the next few years, additional settlements were established, notably Okak(formerly “Okkak”)While conducting their mission, the Moravian Church engaged in, among other things, making meteorological observations of such elements as air temperature (°F), atmospheric pressure (Paris inch and Paris line), wind speed (on a scale 0–6) and wind direction (on an eight-direction compass rose).Atmospheric pressure and wind conditions (force and direction) on the coast of Labrador in the late 18th century were estimated based on meteorological measurements made by the Moravian missionaries. Meteorological observations in Nain were conducted 2–5 times daily from October 1771 to October 1775 and from November 1775 (in Nain) and from October 1776 (in Okak) every four hours: 8:00, 12:00, 16:00 and 20:00 local time (LT). of atmospheric pressure and wind data for Nain spans a very long period (Oct 1771–Jul 1786, 15 expedition years). Wind force and direction were also conducted in Okak, but are available for a shorter period (Oct 1776–Aug 1787).Using publicly available sources, two series of data were developed, one for each station. Meteorological observations at Nain were made for the period Oct 1771 – Jul 1786. During this time, there was a gap in the measurements from 21 Oct 1774 to 16 Sep 1775 and from 12 to 30 Sep 1784. At Okak, observations were made without interruption for the period 16 Oct 1776 – 31 Aug 1786.All available historical data were quality checked and corrected. Air temperature was converted to degrees Celsius. Historical data were quality-checked and corrected. Air temperature was converted to degrees Celsius. Atmospheric pressure to mmHg and them to hPa. The gravity correction "Pφcorr" was then applied, and the pressure was reduced to sea level altitude "SLP" using the formulas provided in Cappelan (2009). Atmospheric pressure was also corrected to the value at 0°C. For this purpose, the Kämtz formula from Können et al. (2003). For more details, see Przybylek et al. (2013). Wind speed was converted from a seven-degree scale (0–6) to a range of values expressed in m∙s˗1, according to the conversion proposal in Chmist et al. (2025). New wind speed classes were defined and assigned appropriate values, see Table in wind_conversion.pdf file.References:Cappelen J (ed.) (2009) DMI monthly climate data collection 1768–2008, Denmark, The Faroe Islands and Greenland, Technical Report 09-05. Dan. Meteorol. Inst.Chmist K, Araźny A, Przybylak R, Wyszyński P, Singh G (2025) Changes in bioclimatic conditions on the coast of the Labrador Peninsula in the second half of the 18th century. Climatic Change 178:46. https://doi.org/10.1007/s10584-025-03883-xKönnen GP, Zaiki M, Baede APM, Mikami T, Jones PD, Tsukahara T (2003) Pre-1872 extension of the Japanese instrumental meteorological observation series back to 1819. Journal of Climate 16:118–131. https://doi.org/10.1175/1520-0442(2003)016&lt;0118:PEOTJI&gt;2.0.CO;2Przybylak R, Wyszyński P, Vizi Z, Jankowska J (2013) Atmospheric pressure changes in the Arctic, from 1801 to 1920. Int. J. Climatol. 33:1730–1760. https://doi.org/10.1002/joc.3546