Bioclimatic indices are very important tools to evaluate the thermal stress of the human body. The aims of this study were to analyze the general bioclimatic conditions in ten big cities in Romania and to find out if there has been any change in five bioclimatic indices over a 56‑year period: 1961–2016. The indices considered were: equivalent temperature, effective temperature, cooling power, universal thermal climate index and temperature-humidity index. They were calculated based on the daily meteorological data of air temperature, relative humidity, and wind speed recorded in 10 weather stations in Romania: Bucharest-Băneasa, Botoșani, Cluj-Napoca, Constanța, Craiova, Galați, Iași, Oradea, Sibiu and Timișoara. The features investigated for trend detection consisted of the frequency and length of the occurrence period for each class and for each index. The test used for trend detection was Mann-Kendall and the magnitude of the trend (the slope) was calculated by employing Sen’s slope method. The main results are based on frequency analysis. Three indices showed comfort class as dominant whereas the other two indicated cold stress conditions as dominant in the area. There was a shift from the cold stress conditions to the warm and hot ones for all the indices. The most stressful conditions for hot extremes did not indicate significant change. The climate in the big cities of Romania became milder during the cold season and hotter during the warm period of the year. The analysis of the length of each thermal class indicated mainly longer occurrence periods during the year for comfortable or warm stress classes.

中文翻译：

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1961–2016年间罗马尼亚大城市中五个生物气候指标的变化

生物气候指数是评估人体热应力的非常重要的工具。这项研究的目的是分析罗马尼亚十个大城市的一般生物气候条件，并找出在56年内（1961-2016年）五个生物气候指数是否发生了变化。所考虑的指标为：当量温度，有效温度，冷却能力，普遍热气候指标和温湿度指标。这些数据是根据罗马尼亚10个气象站记录的每日气温，相对湿度和风速的气象数据计算得出的：布加勒斯特-比尼亚萨，博托沙尼，科鲁-纳波卡，康斯坦察，克拉约瓦，加拉西，雅西，奥拉迪亚，锡比乌和蒂米什瓦拉。趋势检测所研究的特征包括每个类别和每个索引的发生周期的频率和长度。用于趋势检测的测试是Mann-Kendall，趋势的大小（斜率）是通过使用Sen's斜率方法计算的。主要结果基于频率分析。三个指数显示舒适度等级居主导地位，而其他两个指标则以该地区的冷应激条件居主导地位。所有指标均从冷应激条件转变为热应激条件。极端极端情况下压力最大的情况并未表明发生重大变化。罗马尼亚大城市的气候在寒冷季节变得温和，而在一年的温暖时期则更热。