VARIABILITY and CHANGE of HUMIDEX and ABSOLUTE HUMIDITY on the COASTS of TÜRKİYE

Air Temperature and relative humidity are the primary variables that determine thethermal comfort of living organisms. The presence of humidity in the air has effects onthe perceived temperature, and on hot summer days with high humidity, the temperaturefeels higher than what the thermometer measures. The concept of humidex wasintroduced to explain the impact of humidity on perceived temperature. Humidex isparticularly significant in coastal areas where humidity can be high, affecting thermalcomfort and human health. As the air temperature increases, both the amount ofevaporation and the amount of humidity the air can hold also increase.Türkiye is a topographically high and rugged country consisting of two peninsulas,Anatolia and Thrace. A significant portion of the country's population resides along thecoasts. Additionally, tourism activities in coastal areas are more intense during thesummer months compared to other seasons. Türkiye is considered among the high-riskcountries for the adverse effects of climate change, especially since it is located in theEastern Mediterranean Basin where the impacts of climate change are expected to beintense.The aim of this study is to identify the regions on the coasts of Türkiye wherehumidex increases and decreases during the summer months, and thus investigate theevolution of the comfort level of coastal residents and the impact of humidex fluctuationson living comfort. In the study, areas where humidex increases and decreases on thecoasts of Türkiye are identified, and these trends are visualized, determining the directionof future changes in humidex. Relative humidity and air temperature data obtained fromstations operated by the Turkish State Meteorological Service (MGM) in 61 differentsettlements along the coastal regions of Türkiye are used for calculating humidex. Thesedata consist of hourly measurements taken in June, July, and August. Humidex andabsolute humidity are calculated using hourly relative humidity and air temperature data,and absolute humidity analysis is conducted to understand the cause of trends in humidex.The variability and changes in humidex (perceived temperature with humidity) from 1990to 2022 are analyzed using the Mann-Kendall test, Sen's trend slope method, correlationanalysis, and regression analysis.The outputs obtained from the analysis of the variability and changes in humidexin coastal areas with high population and tourism density will serve as a reference formeasures to be taken for both human health and thermal comfort. The study results willprovide a projection for urban planning, tourism, and cooling systems.In all 61 stations examined on the coasts of Türkiye, the air temperature hasincreased. In 90% of these 61 stations, it has been determined that humidex has increasedat least twice the rate of air temperature. The increase in air temperature has increasedevaporation and the air's capacity to carry humidity in all locations.