Volume XVIII |

Climate parameters relevant for avalanche triggering in the Făgăraș Mountains (Southern Carpathians)

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.

Volume XVIII |

A review of recent studies on heat wave definitions, mechanisms, changes, and impact on mortality

Abstract: Heat waves (HWs) represent a major danger to society and natural environment. The increasing occurrence of high magnitude and impact HWs has raised concerns worldwide and has attracted an increasing interest on this issue among climatologists over the past decade. In this review the research from 2007-2018 period on HWs definitions, driving mechanisms, present changes, future changes, and impact on human mortality is summarized. By reviewing the recent literature, it was found that whilst the atmospheric dynamic is considered to be the primary driver in HW occurrence, the sea surface temperature (SST) and land surface conditions are also essential driving components. The vastness of HW-definitions raises difficulties in selecting the appropriate methodology to identify heat episodes and to compare results from studies which used different definitions. However, by analyzing a sample of 109 papers, a preference for percentile-based definitions was observed. Therefore, 71.6% of the analyzed articles used only percentile-based definitions to identify HWs. Despite the wide variety of definitions, the analysis of changes in HWs converged to similar results. Thus, the existing recent literature provided extensive evidence of significant increase in HWs characteristics across large regions of the planet. Available scientific literature indicated that HWs have been responsible for a considerable increase in mortality in many regions of the world. In the future HWs are predicted to increase in their main characteristics leading to a greater impact on human mortality. Nevertheless, the implementation of rigorous adaptation measures can mitigate the negative impact on mortality. In conclusion, it was noted that a substantial progress has been done in the HW research, but there are still important gaps in this issue which need to be addressed.

Volume XI |

The wind regime of Romania – Characteristics, trends and North Atlantic oscillation influences

Abstract: The present study attempts to develop a comprehensive perspective of the wind regime on the Romanian territory, focusing on the characteristics and tendencies encountered over the past 50 years, as well as on the NAO projection on it, using several data categories gathered from 167 meteorological stations. Based on the recorded multiannual averages and on the strong correlation (r = 0.87) established between altitude and wind speed in wind exposed areas, we created the map of mean (multi)annual wind speed. The highest aeolian potential corresponds to the Carpathians (7-10 m/s on the ridges and 3-7 m/s on the slopes and within valleys) and the Black Sea Shore (5-7 m/s); nevertheless, the two areas develop extreme values of the wind turbulence – maximum in the Carpathians and minimum in the coastal units. Tablelands in Moldova and Dobrogea, as well as the northern part of Bărăgan show ideal conditions for the development of aeolian parks (moderate and strong winds, low turbulences). On a country-size scale, the month with the highest mean wid speed is March, whereas August is the calmest one. For the first time, the map of resultant wind direction (DRV) was designed, expressing both the resultant wind orrientation and its intensity (high intensity = low directional variability). Concerning NAO, a negative correlation is observed between its indices and the wind speed (mean speed, frequency and intensity of the stromic events) at a multiannual and multidecadal scale. The correlation coefficients present high values in the extra-carpathian areas and small or moderate values in the intra-carpathian areas. The positive (negative) NAO associated with low (high) cyclogenesis over the Mediterranean area induce low (high) winds over the Romanian territory due to diminished (enhanced) frequency of cyclones reaching Romanian regions.