Multi-Annual Changes in Heat Stress Occurrence and Its Circulation Conditions in the Polish–Saxon Border Region

Bartłomiej Miszuk

doi:10.3390/atmos12020163

Abstract

Heat stress is one of the most critical factors affecting human life. In Central Europe, its influence is noticeable, especially in the Polish–Saxon region, which is a very popular tourist region also inhabited by a high number of elders. The main goal of this paper was to assess multi-annual changes in heat stress occurring in the region, considering the frequency of heat days, the UTCI (Universal Thermal Climate Index), and circulation conditions. The research showed that all the thermal and biothermal indices in this region significantly increased during 1971–2019 in the lowlands, the mountain foreland, and the lower mountain zone. In terms of the UTCI, a negative trend for cold stress frequency was noticed in the entire region in favor of an increase in a tendency toward thermoneutral conditions and heat stress. This concerns especially strong and very strong heat stress (UTCI > 32 °C), in which positive trends were observed for most of the stations located in the lower hypsometric zones. The results also showed that heat stress mainly occurs on days with anticyclonic circulation. Analysis of selected cases of heat waves in the 21st century indicated that the lower hypsometric zones are characterized by a very high UTCI, while the summit zone is free from heat stress occurrence.

Highlights

Heat stress is one of the most characteristic weather features affecting human life.High air temperature, humidity, low wind speed, and the influence of solar conditions increase the intensity of the heat load on the human organism, which results in a high risk for health
Humidity, low wind speed, and the influence of solar conditions increase the intensity of the heat load on the human organism, which results in a high risk for health
Based on Changes in the mean air temperature over the past decades were reflected in the these records, analysis of circulation conditions in the context of the frequency of heat positive trend in the maximum air temperature and caused an increase in days and selected universal thermal climate index (UTCI) categories was carried out

Summary

Introduction

Heat stress is one of the most characteristic weather features affecting human life.High air temperature, humidity, low wind speed, and the influence of solar conditions increase the intensity of the heat load on the human organism, which results in a high risk for health. Studies concerning problems of temporal variability of heat stress showed that the frequency of such weather conditions in Europe had significantly increased [3,4,5,6,7,8,9,10,11,12,13]. Such a growing tendency is contributed by frequent heat waves that have been recorded multiple times over the past two decades. In some regions of Germany, the mortality in August 2003 and July 2015 exceeded the normal rate by 70% and 56%, respectively [25]

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