Thermal Conditions in the City of Poznań (Poland) during Selected Heat Waves

Marek Półrolniczak,Leszek Kolendowicz,Arkadiusz Tomczyk

doi:10.3390/atmos9010011

Abstract

The aim of the study was to characterise the occurrence of hot days and heat waves in Poznań in the 1966–2015 period, as well as to describe the thermal conditions in the city during selected heat waves between 2008 and 2015. The basis of the study was the daily maximum and minimum air temperature values for Poznań–Ławica station from 1966–2015 and the daily values of air temperature from eight measuring points located in the city in various land types from 2008 to 2015. A hot day was defined as a day with Tmax above the 95th annual percentile (from 1966 to 2015), while a heat wave was assumed to be at least five consecutive hot days. The research study conducted shows the increase of Tmax, number of hot days and frequency of heat waves in Poznań over the last 50 years. Across the area of the city (differentiation of urban area types according to Urban Atlas 2012), there was a great diversity of thermal conditions during the heat waves analysed.

Highlights

Today’s climate warming is unmistakable and visible, among other manifestations, in the increase in global average air temperature [1]
A statistically significant (p < 0.05) increase in the maximum (Tmax) was observed in the period analysed, which was 0.35 ◦ C per 10 years
The aforementioned increase was significantly influenced by Tmax changes at the beginning of the 21st century, when its value in almost all summer seasons was higher than the average for the 1966–2015 period (Figure 2)

Summary

Introduction

Today’s climate warming is unmistakable and visible, among other manifestations, in the increase in global average air temperature [1]. An increase in the frequency of heat waves and their duration is expected, which will be a consequence of the increase in air temperature [7,8]. Urban areas are vulnerable to prolonged and intense heat waves [10], which is a consequence of the transformation of the environment. The small proportion of natural vegetation, numerous vertical surfaces and human activity causes significant heat in the city during the day, which is released into the atmosphere, causing it to cool down more slowly than the surrounding areas [11]. Numerous studies have shown an increase in the number of deaths during heat waves in large cities, including in Warsaw [13], Munich [14] and

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Discussion

Conclusion