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Comparison of early twentieth century Arctic warming and contemporary Arctic warming in the light of daily and sub-daily data

Przybylak, Rajmund 1 ; Wyszynski, Przemyslaw 2 ; Arazny, Andrzej 3

1 Nicolaus Copernicus University, Faculty of Earth Sciences and Spatial Management and Centre for Climate Change Research
2 Nicolaus Copernicus University, Faculty of Earth Sciences and Spatial Management and Centre for Climate Change Research
3 Nicolaus Copernicus University, Faculty of Earth Sciences and Spatial Management and Centre for Climate Change Research

A summary of a large number of studies conducted since the late 1920s reveals that there is still no definite explanation of the main driving mechanisms responsible for the Early Twentieth Century Arctic Warming (ETCAW). Limited knowledge about the climate of this period, and about some forcings, seems to be the main obstacle to reaching the goal. What is required is better knowledge based on data of resolution that is greater than monthly, i.e. daily and sub-daily. The main objective of this article is to provide a comprehensive description of surface air temperature (SAT) conditions in the Arctic during the ETCAW using available long-term series of daily and sub-daily data taken from five meteorological stations representing main climatic regions in the Arctic. Four thermal parameters from 10 years were used for this purpose: mean daily air temperature, maximum and minimum daily temperature, and diurnal temperature range. Analysis of rarely investigated aspects of SAT characteristics (e.g.: number of characteristic days; day-to-day temperature variability; and onset, end and duration of thermal seasons) was also conducted. The results were compared with analogical calculations done for data taken from the Contemporary Arctic Warming (CAW) period (2007–16). The Arctic showed an increase in mean annual SAT between the ETCAW and the CAW with the greatest magnitude in the Pacific (2.7 °C) and Canadian Arctic (1.9 °C) regions and the smallest (0.2 °C) in the Baffin Bay region. Climate continentality in the Arctic was usually 1–4% greater during the ETCAW than during the CAW, except in the Siberian region.

The study was carried out as a part of the scientific project entitled “Causes of the early 20th century Arctic warming”, funded by the National Science Centre, Poland (Grant No. 2015/19/B/ST10/02933), and the Research University – Initiative of Excellence: the Emerging Field “Global Environmental Changes”, "Climate Change Research Unit" at Nicolaus Copernicus University in Toru?. 20th Century Reanalysis V3 data was provided by the NOAA/OAR/ESRL PSL, Boulder, Colorado, USA, from their website https://psl.noaa.gov/data/gridded/data.20thC_ReanV3.html. Support for the Twentieth Century Reanalysis Project version 3 dataset is provided by the U.S. Department of Energy, Office of Science Biological and Environmental Research (BER), by the National Oceanic and Atmospheric Administration Climate Program Office, and by the NOAA Physical Sciences Laboratory.