Biometeorological Conditions during the August 2015 Mega-Heat Wave and the Summer 2010 Mega-Heat Wave in Ukraine

Biometeorological conditions during cold spells in south-east Poland and west Ukraine

The aim of this research is to analyze the biometeorological conditions, based on the Physiologically Equivalent Temperature (PET) thermal index, during cold spells (CSs) in south-east Poland and west Ukraine during the years 1966-2021. The research shows a high variability of the occurrence of CSs in the study period and a clear increase in the frequency and total duration of CSs in the east of the study area. The number of CSs in the analyzed years varies from 6 cases in the west (in Katowice) to 34 in the east of the study area (in Shepetivka). The total duration of CSs varied from 26 days (in Raciborz and Katowice) to 166 days (in Rivne). At the majority of stations, CSs occurred most frequently in the first two decades (1966/1967-1975/1976, 1976/1977-1985/986) and in the last full decade (2006/2007-2015/2016). The average PET values at 12:00 UTC during CSs decreased eastwards throughout the study domain and were generally lower than -20.0 °C in the west of Ukraine, while in south-east Poland varied between -18.1 and -20.0 °C. At 40% of stations across the study domain, the lowest average PET values were recorded during a cold spell in January 1987, with PET values varying from -28.0 °C in Chernivtsi to -12.7 °C in Yaremche. The longest or one of the longest spells in most stations (in 77% of stations across the study domain) was the cold spell of 2012 and characterized by mean PET values ranging from -25.4 °C in Rivne to -19.5 °C in Zakopane.

Analysis of long- and short-term biometeorological conditions in the Republic of Serbia

Long- and short-term biometeorological conditions in the Republic of Serbia were analyzed using official meteorological data from numerous weather stations located across the country. Selected biometeorological indices HUMIDEX, Physiologically Equivalent Temperature (PET), and Universal Thermal Climate Index (UTCI) are calculated based on air temperature, relative humidity, wind speed, and cloudiness data from the meteorological stations on annual and summer level as well as during selected heat wave periods during 2000-2020. Application of different biometeorological indices provides similar but somewhat different results. For example, average annual HUMIDEX and UTCI values indicate no thermal stress and no discomfort at all stations, while PET indicates the occurrence of slight to moderate cold stress at all stations. Average summer PET and UTCI indicate the occurrence of slight to moderate heat stress throughout the country, while HUMIDEX indicates no discomfort. Trends of biometeorological indices on annual and summer level show a general increase throughout the country. Furthermore, heat wave analysis indicated that the most populated cities of Serbia are under dangerous and extreme heat stress during these extreme temperature events, which can influence human health and well-being. The obtained biometeorological information can be used for the preparation of climate adaptation strategies that consider the human biometeorological conditions, with a special focus on developing climate-sensitive and comfortable cities.

Interannual Variability of Summer Hotness in China: Synergistic Effect of Frequency and Intensity of High Temperature

In the context of global warming, the impact of summer high temperature events is increasing. The accumulated summer high temperature is often used to reflect the overall hotness of summer. The internal variation of the accumulated temperature can be affected by both the frequency and intensity. In this study, by using the daily data during summers of 1960–2018, we examine the relative importance of the two factors with a multiple linear regression method. It is demonstrated that that the dominant result of summer accumulated temperature is sensitive to the change of threshold. As the threshold increases, the importance of frequency gradually increases, while the importance of the intensity decreases. In addition, it is found that when the threshold changes, the sensitivity of the dominant results is different over regions. This can provide a basis for the selection of regional thresholds and further improve the representation of accumulated temperature for high summer temperatures.