This article provides the first country-scale climatology of the Surface Urban Heat Island (SUHI) investigated across the cities with more than 30,000 inhabitants from Romania using using the MODIS Land Surface Temperature (LST) data set developed within the Land Surface Temperature Climate Change Initiative (CCI) project (LST_cci), funded by European Space Agency. The main findings refer to the relationship between air temperature and LST, temporal variability of the LST over selected urban areas, and the country-scale variations of the SUHI intensity (SUHII), defined as the thermal contrast between the city and its rural proximity. Night- and day-time conditions introduce major differences, the seasonality is an important bias, and the results are presented accordingly. The LST is very well correlated with air temperature (T2m) under clear-sky conditions. At nighttime, the average SUHII is around 0.9 °C in all summer months, while at daytime the average SUHII equals 2.5 °C, in June, 2.3 °C in July, and 1.9 °C in August. The results are relevant for clear-sky conditions and show that the city size (mainly the log transformed area size), climate type (i.e., Cfa, and Cfb, by nightime, and Cfb, and Dfb, by daytime), and land use-land cover (LULC) conditions (i.e., Urban fabric) amplify the magnitude of the SUHII across Romania.

本文使用在地表温度气候变化倡议中开发的 MODIS 地表温度 (LST) 数据集，对来自罗马尼亚的超过 30,000 名居民的城市进行了首次全国范围的地表城市热岛 (SUHI) 气候学调查(CCI) 项目 (LST_cci)，由欧洲航天局资助。主要发现涉及气温和 LST 之间的关系、LST 在选定城市地区的时间变化以及 SUHI 强度 (SUHII) 的国家尺度变化，定义为城市与其农村邻近地区之间的热对比。夜间和白天条件引入了重大差异，季节性是一个重要的偏差，结果相应地呈现。在晴空条件下，LST 与气温 (T2m) 的相关性非常好。在夜间，所有夏季月份的平均 SUHII 约为 0.9 °C，而在白天，平均 SUHII 为 2.5 °C，6 月为 2.3 °C，7 月为 2.3 °C，8 月为 1.9 °C。结果与晴空条件相关，并表明城市规模（主要是对数转换面积大小）、气候类型（即 Cfa 和 Cfb，夜间，Cfb 和 Dfb，白天）和土地利用- 土地覆盖 (LULC) 条件（即城市结构）放大了整个罗马尼亚的 SUHII 的大小。