Homogenization of air temperature and its long-term trends in Poznań (Poland) for the period 1848–2016

Abstract

A long-term series of meteorological measurements will allow for a better understanding of the rate and nature of climate change. Such analysis presumes a historical knowledge of the particular place of measurements and changing measurement techniques, as well as a further evaluation of the quality of the available data. This research focuses on the city of Poznań and temperature measurements conducted from 1848 to 2016. By 1919, the location of meteorological stations had changed five times, causing time-series inhomogeneities. In 1921, meteorological measurements began to be carried out at the Poznań-Ławica airport, which have there been maintained to this day. The monthly means of air temperature for the period 1848-1919 clearly indicate a break in their homogeneity. For this reason, the main objective of this study is to reconstruct the 169-year long air temperature records in a homogeneous way so as to make it coherent with the surrounding series of long-term measurements. Data gaps are supplemented by the constant difference method based on the homogenized data series from the nearest stations. The monthly means are homogenized according to the Alexanderson's Standard Normal Homogeneity Test. In addition, evaluation of the annual, seasonal, and monthly temperature trends is also provided. An increasing long-term trend can be observed for the entire period of analysis. For the years 1848-2016, the air temperature grew at a rate of 1.1°C per 100 years. As far as seasons go, the highest increase was observed in Winter (+ 1.5°C/100 years) with the lowest in Summer (+ 0.6°C/100 years). In the last 30 years, the pace of trend has increased to a rate of + 4.6°C per 100 years, with the highest values recorded for Summer (+ 7.5°C/100 years).

The extreme year—analysis of thermal conditions in Poland in 2018

“…As emphasised by some authors, the situation was unprecedented, because three record years in a row had never occurred before. Kolendowicz et al (2019) analysing thermal conditions in Poznań (Poland) in the years 1848-2016 evidenced that 7 out of 10 warmest years occurred in the twenty-first century, and the warmest year was 2014. According to NOAA (2019), in the years 1880-2018 at the global scale, 9 out of 10 warmest years are those after the year 2000, with a maximum in 2016 (mean anomaly 0.95°C).…”

Homogenization of a combined hourly air temperature dataset over Romania

“…(Guijarro, 2017;Guijarro, 2018). The Climatol method has been successfully used to homogenize air temperature data (Mamara et al, 2013;Kolendowicz et al, 2019) (Luna et al, 2012). Climatol was also tested against realistic benchmark datasets and returned very good results comparable to other homogenization methods which are currently used by the climatology community (Venema et al, 2012;Guijarro et al, 2017).…”

“…Kolendowicz et al . () used Alexanderson's Standard Normal Homogeneity Test to reconstruct the 169‐years air temperature measurements available at Poznan, Poland. Osadchyi et al .…”

“…Some recent publications can be acknowledged as relevant for this study. Kolendowicz et al (2019) used Alexanderson's Standard Normal Homogeneity Test to reconstruct the 169-years air temperature measurements available at Poznan, Poland. Osadchyi et al (2018) applied HOMER approach to improve the quality of the monthly air temperature dataset collected in Ukraine from 178 stations between 1946 and 2014.…”

Lidar-Derived Tree Crown Parameters: Are They New Variables Explaining Local Birch (Betula sp.) Pollen Concentrations?

“…The climate is warm temperate and humid with warm summers [37]. The warmest month is July (mean temperature is 18.1 • C), and the coldest month is January (−1.6 • C) [38]; however, in recent years, July has often been warmer than 20 • C, and the mean temperature in January has mostly been above zero [39]. The total precipitation per year is 529 mm (1951-2000 average) [38].…”