Combining stochastic models of air temperature and vapour pressure for the analysis of the bioclimatic comfort through the Humidex

Abstract

Several studies evidenced the importance of the knowledge of the bioclimatic comfort for improving people's quality of life. temperature and relative humidity are the main variables related to climatic comfort/discomfort, influencing the environmental stress in the human body. In this study, a stochastic approach is proposed for characterizing the bioclimatic conditions through the Humidex values in six sites of calabria (southern italy), a region often hit by heat waves in summer months. the stochastic approach is essential, because the available time series of temperature and relative humidity are not long enough and present several missing values. the model allowed the characterization of sequences of extreme values of the Humidex. Results showed different behaviours between inner and coastal stations. For example, a sequence of 20 consecutive days with maximum daily Humidex values greater than 35 has a return period ranging from 10 to 20 years for the inner stations, while it exceeds 100 years for the coastal ones. The maximum yearly Humidex values for the inner stations have a larger range (40-50) than the coastal ones (38-45), reaching higher occurrence probabilities of serious danger conditions. Besides, the different influence of temperature and relative humidity on the Humidex behaviour has been evidenced. Bioclimatic comfort is a cognitive process that mixes many stimuli influenced by physical, physiological, and psychological factors 1. Previous researches evidenced the fundamental importance of the knowledge of the bioclimatic comfort for improving people's quality of life. In fact, in the last years temperatures over 36 °C, especially in situations of heat waves, severely affected people's health, mainly if children, elderly and chronically ill 2,3. An increase of severe heat waves in the current century has been forecasted in areas already affected by heat stress, such as the southern part of the European continent 4-6 and the Mediterranean basin, which is expected to face particularly high impacts from global warming and climate change and to be most vulnerable to their deleterious effects 7. The effects of heat can be various: increase of mortality 8 , working/exercise capacity 9,10 and cognitive performance 11,12. For the analysis of bioclimatic comfort, in studies conducted at different spatial scales in various parts of the world (e.g. in America 13-16 , in Europe 17-19 , in Asia 20-22 and in Oceania 23) several parameters such as temperature, relative humidity of the air, wind and radiation have been analysed. In particular, given their influence on the environmental stress in the human body, temperature and the relative humidity of the air are the key basic parameters related to climatic comfort/discomfort 1. In fact, as stated by Masterton and Richardson 24 , with different humidity conditions the same temperature can provide very different feelings to people. For this reason, in order to detect the effect of heat on human health, an index that combines the effects of temperature and humidit...

Characterization of the 2017 Summer Heat Waves and Their Effects on the Population of an Area of Southern Italy

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