Diurnal temperature range (DTR) is an important index in climate change studies in addition to its influence upon environment and thermal comfort. Understanding variability in DTR at regional scales is, thus, important. In Fiji and other Pacific Island countries, DTR information is important in forecasting thermal comfort. This work is based on Fiji using gauge-based gridded mean monthly DTR data from the Climatic Research Unit (CRU). Annual and monthly DTR for the second half of the twentieth century to the present day are analyzed to establish temporal trends and spatial patterns. A combination of parametric and non-parametric tests was applied to investigate trend, correlation, simple linear regression, and interannual variability in the datasets. Findings show that DTR increases with an increase in latitude over Fiji. The mean monthly DTR between 6.58 and 7.37 °C in June and January coincide with winter and summer, respectively. Cumulative annual mean (CAM) of T, Tmx, and DTR showed increasing trends during the study period while the CAM of Tmn depicted a decreasing trend. Results suggest that DTR has a positive significant (insignificant) correlation with Tmx (T), but shows an opposing significant relationship with Tmn at 5% significance level. Each of DTR, Tmx, Tmn, and T experienced a general increase in values across the timeframe provided by the data. Records show an overall increase of 0.05 °C/decade in DTR. However, since the early 1990s, DTR has been characterized by a downward trend. Nonetheless, the overall trend of increasing DTR is explained by a greater increase in maximum temperatures over minimum temperatures. The observed rate of increase in DTR in warm months exceeds that in cold months. The findings form a baseline for further studies investigating the factors influencing DTR variability, and how the variability is affecting human thermal comfort.

中文翻译：

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太平洋岛国昼夜温差变化，斐济案例研究

除了对环境和热舒适度的影响外，昼夜温差（DTR）是气候变化研究中的一个重要指标。因此，了解区域尺度上 DTR 的可变性很重要。在斐济和其他太平洋岛国，DTR 信息对于预测热舒适度很重要。这项工作基于斐济，使用来自气候研究单位 (CRU) 的基于仪表的网格平均每月 DTR 数据。分析 20 世纪下半叶至今的年度和月度 DTR，以建立时间趋势和空间模式。应用参数和非参数测试的组合来研究数据集中的趋势、相关性、简单线性回归和年际变化。研究结果表明，DTR 随着斐济纬度的增加而增加。6 月和 1 月的月平均 DTR 介于 6.58 和 7.37 °C 之间，分别与冬季和夏季重合。T、Tmx 和 DTR 的累积年平均值 (CAM) 在研究期间呈上升趋势，而 Tmn 的 CAM 呈现下降趋势。结果表明，DTR 与 Tmx (T) 具有显着正相关（不显着），但在 5% 显着性水平上与 Tmn 显示出相反的显着关系。在数据提供的时间范围内，DTR、Tmx、Tmn 和 T 中的每一个都经历了值的普遍增加。记录显示 DTR 总体增加了 0.05 °C/十年。然而，自 1990 年代初以来，DTR 一直呈下降趋势。尽管如此，DTR 增加的总体趋势是通过最高温度超过最低温度的更大增加来解释的。观察到的温暖月份 DTR 的增加率超过了寒冷月份。这些发现为进一步研究调查影响 DTR 变异性的因素以及变异性如何影响人类热舒适性奠定了基础。