Abstract: The paper characterizes thermal and humidity conditions within one of the insufficiently investigated parts of Bulgaria from the climate point of view, namely the south-western slope of the Pirin Mountains. The initial data for the study (monthly temperatures and precipitation amounts) were obtained from our own meteorological monitoring station for the period 2013-2021, organized by the Department of Climatology, Hydrology and Geomorphology, Sofia University, Bulgaria. By the calculation of Mayr tetratherm (MT), monthly De Martonne aridity index (Im) and Compensated Summer Ombrothermic index (CSOi) the predominance of humid conditions in the studied area is established. There is a large inter-annual variability of the De Martonne aridity index and the Compensated Summer Ombrothermic index, which are more influenced by precipitation than air temperature in the middle part of the mountains. On the other hand, in combination with low precipitation amounts, high temperatures in recent years have contributed to the manifestation of arid features of the climate. The results of the study supplement the insufficient information about the bioclimatic characteristics of the Pirin Mountains and clarify the peculiarities of the climate in these mountains, which have two clearly distinguishable macroslopes with west-southwest and east-northeast exposure.
Abstract: The climate change on a global, regional and local scale is one of the largest problems indicated by the 21st century studies. Some of the major climate changes on the Balkan Peninsula, and in particular in Bulgaria, are related to rising temperatures and decreasing precipitation, which leads to drought and climate aridity. The present study focuses on the investigation of the climate aridity in the non-mountainous part of Southern Bulgaria in order to assess the aridity condition in temporal and spatial scale. The main investigated period is 1961-2015 and the reference periods are 1961-1990 and 1986-2015. The aridity is analysed on the basis of monthly data for air temperatures and precipitation from eight meteorological stations by calculation of De Martonne aridity index and Emberger Index. The survey shows that in all the analysed meteorological stations in Southern Bulgaria there are periods which display characteristics of the semiarid or arid climate. The aridity is well-expressed in the southwest part of Bulgaria (station Sandanski) and the western part of the Thracian lowland (station Plovdiv). Despite the aridity conditions established in the investigated region the tendencies in multiannual variability of De Martonne and Emberger indices show decreasing of aridity during the last 30 years (1986-2015) of the investigated period.
Abstract: The climate conditions may contribute significantly to the generation of several hazards in mountain areas, such landslides, wildfires, flash floods and avalanches. This study examines the variation of the main meteorological parameters with impact on avalanche triggering conditions at Bâlea-Lac Meteorological Station. At the best of our knowledge, this is the first overview of the basic climate parameters which are potentially avalanche triggers in the Făgăraș Mountains (Southern Carpathians). The study is based on data from only one weather station (Bâlea-Lac) from the period 1979-2017, assuming it is consistently relevant from climatic point of view for avalanche occurrence in the area. The results demonstrate that the theoretical circumstances for avalanche triggering (e.g. snow pack, fresh snow or wind) can be captured. This paper briefly describes the nivologic monitoring system run by the National Meteorological Administration and emphasises its utility for avalanche forecasting and alerts.
Abstract: Almost 90 years from the radar invention, the radar technology has evolved enormously and today it presents itself as an instrument of great importance in various research areas (meteorology, aviation, astronomy, air-ecology etc.). The main objective of the article is to identify the periods of development at the global level and also in Romania, as well as to identify the technology of most operational weather radars today. The article is based on publications from international journals and scientific books, covering the period of 1930-2018. The overview presentation demonstrates the reasons today’s weather radar is a powerful tool for studies concerning the atmospheric precipitations prediction, wind speed and direction, rainfall risk assessment and implementation of weather forecasts. Knowing the technological development is needed for the construction of the new generation radar and for exceeding the actual limits with regard to the accuracy of the radar data and the limits of observation. The purpose of this article is to summarize the evolution of the weather radar, with emphasis on the first experiments carried out during the analogue and digital period.