Long-Term Air Temperature Variations in Some Urban Areas of Sofia Valley in the Context of Climate Change

摘要

The question of the influence of urban agglomerations on the climate is relevant since today around 50% of humanity lives in cities. Increasing urbanization leads to the emergence of more and more cities with enormous size and multi-million populations. Worldwide increasingly great attention is paid to the link between urbanization and global climate change. Cities consume over 70% of the world's energy and produce more than 60% of the carbon dioxide, as well as a significant portion of the remaining greenhouse gas emissions, which alter the composition of the atmosphere. The impact of urbanization on the climate is complex. In the recent years, in Bulgaria, as in other countries, changes in the course of the main climatic parameters are observed and these changes are well expressed in the big cities. Sofia is the largest urban and industrial center in Bulgaria, in which the anthropogenic impact on the climate is the most highly expressed. Some of the peculiarities of urban climate in Sofia were established back in the 1930s. In the recent decades, the growing city covers ever greater areas of the Sofia Valley and currently more than 15% of the population of the country is concentrated herein, which necessitates to be carried out studies on climatic fluctuations in the urban and suburban areas, particularly in the context of climate change. The subject of the presented research is the spatiotemporal variation of air temperature in the urban areas within the Sofia Valley. The selection of meteorological stations in the study is based on the degree of urbanization: one station located in a high-anthropogenic urban environment (Sofia) and two other located in small settlements (Bankya and Bozhurishte), as well as on the quality of the available meteorological information. The aim of the work is to contribute to the clarification of the contemporary changes of air temperature characteristics in the cities in the process of urban heat island formation, along with the det