Nigeria's growing population faces an increasing heat burden with potential health risks. The Universal Thermal Comfort Index (UTCI) links outdoor conditions and human well-being but lacks comprehensive data in developing regions like Nigeria. ERA5-HEAT reanalysis offers a solution with gridded UTCI and MRT data, but validation is crucial. Thus, this study evaluates the ERA5-HEAT UTCI against data from nine Nigerian weather stations and analysed the spatio-temporal patterns of heat stress trends. Results showed that ERA5-HEAT demonstrated reasonable statistical performance and captured the temporal characteristics and patterns of UTCI across Nigeria's climatic zones. Seasonal variations show heat stress levels from "slightly cold" to "moderate" at 0600 LST and "moderate" to "very strong" at 1500 LST. Geographical consistency exists within each season over the decades, with a critical "very strong" heat stress period during March-May. Additionally, there has been an increasing spatial expansion of areas experiencing higher heat stress levels across the country. Latitudinally, stable patterns exist across decades at 0600 LST for each season. Seasons show distinct UTCI values, and at 1500 LST, more variability and category transitions occur along latitudes. Furthermore, the results indicate significant positive trends and occasional non-significant negative trends over the 40-year period. Notably, during 0600 LST, the Guinea and Sahel regions exhibit relatively higher positive trends than the Sudan region in all seasons, whereas at 1500 LST, high positive trends are prominent in DJF and MAM seasons, indicating increased heat stress during peak seasons. These positive deviations in UTCI are associated with adverse effects on human health, including increased mortality rates.

中文翻译：

---

使用评估的 ERA5-HEAT 再分析数据分析尼日利亚热应激的时空特征


尼日利亚不断增长的人口面临着日益严重的高温负担和潜在的健康风险。通用热舒适指数 (UTCI) 将户外条件和人类福祉联系起来，但缺乏尼日利亚等发展中地区的全面数据。 ERA5-HEAT 再分析提供了包含网格 UTCI 和 MRT 数据的解决方案，但验证至关重要。因此，本研究根据来自尼日利亚九个气象站的数据评估了 ERA5-HEAT UTCI，并分析了热应激趋势的时空模式。结果表明，ERA5-HEAT 表现出合理的统计性能，并捕获了尼日利亚各气候带 UTCI 的时间特征和模式。季节变化显示，热应激水平在 0600 LST 时为“微冷”至“中度”，在 1500 LST 时为“中度”至“非常强”。几十年来每个季节都存在地理一致性，三月至五月是一个关键的“非常强”的热应激期。此外，全国范围内热应激水平较高的地区不断扩大。在纬度上，每个季节在 0600 LST 处存在数十年的稳定模式。季节显示不同的 UTCI 值，并且在 1500 LST 处，沿纬度发生更多变化和类别转换。此外，结果表明 40 年来存在显着的积极趋势和偶尔的非显着的消极趋势。值得注意的是，在LST 0600时，几内亚和萨赫勒地区在所有季节都表现出比苏丹地区更高的正向趋势，而在LST 1500时，DJF和MAM季节的高正向趋势突出，表明旺季热应激增加。 UTCI 的这些正偏差与对人类健康的不利影响有关，包括死亡率增加。