Wang You-Ren, Samset Bjørn H, Stordal Frode, Bryn Anders, Hessen Dag O
Dept. Marine Environment and Engineering, National Sun Yat-sen University, Kaohsiung 80424, Taiwan; Graduate Institute of Marine Affairs, National Sun Yat-sen University, Kaohsiung 80424, Taiwan; Dept. Biosciences and Centre for Biogeochemistry in the Anthropocene, University of Oslo, Oslo 0316, Norway.
CICERO Center for International Climate Research, Oslo 0349, Norway.
Sci Total Environ. 2023 Dec 15;904:166727. doi: 10.1016/j.scitotenv.2023.166727. Epub 2023 Sep 4.
Temperature anomalies and changes in the diurnal temperature range (DTR) are expected to pose physiological challenges to biota; hence, both spatial and temporal variations in DTR provide important insights into temperature-induced stress in humans, animals, and vegetation. Furthermore, vegetation could dampen temperature variability. Here, we use the Moderate Resolution Imaging Spectroradiometer (MODIS) remote sensing data of Land Surface Temperature (LST) to evaluate the global variation in DTR and its rate of change in spatial and temporal scales for the two decades spanning from 2001 to 2020. We show that North America, Africa, and Antarctica, as well as the global mean, experienced statistically significant DTR rates of change over the last 20 years in either summer, winter, or the annual mean. The rates were all negative, indicating the day-night temperature differences are decreasing in those regions because night temperatures are increasing at a faster rate than day temperatures. MODIS data of the Normalized Difference Vegetation Index (NDVI) revealed a strongly negative correlation with DTR, with a spatial correlation coefficient of -0.61. This correlation demonstrates a prominent dampening effect of vegetation on diurnal temperature oscillations. For future DTR projections, we used 19 models in the Coupled Model Intercomparison Project 6 (CMIP6) to predict global DTR trends from 2021 to 2050 with low and high CO concentration scenarios. The high CO emission scenario projects significant decreases in DTR in circumpolar regions, central Africa, and India compared to the low CO scenario. This difference in the two scenarios underscores the substantial influence of increased global temperatures and elevated CO concentration on DTR and, consequently, on the ecosystems in certain regions.
温度异常和日较差（DTR）的变化预计会给生物群带来生理挑战；因此，DTR的时空变化为了解温度对人类、动物和植被造成的压力提供了重要线索。此外，植被可以缓冲温度变化。在此，我们利用中分辨率成像光谱仪（MODIS）的地表温度（LST）遥感数据，评估2001年至2020年这二十年中DTR的全球变化及其在时空尺度上的变化率。我们发现，北美洲、非洲和南极洲以及全球平均值在过去20年的夏季、冬季或年平均值中，DTR变化率具有统计学意义。这些变化率均为负值，表明这些地区的昼夜温差正在减小，因为夜间温度的上升速度快于白天温度。归一化植被指数（NDVI）的MODIS数据显示与DTR呈强负相关，空间相关系数为-0.61。这种相关性表明植被对昼夜温度振荡具有显著的缓冲作用。对于未来的DTR预测，我们使用了耦合模式比较计划第6阶段（CMIP6）中的19个模型，在低CO浓度和高CO浓度情景下预测2021年至2050年的全球DTR趋势。与低CO情景相比，高CO排放情景预测环极地区、非洲中部和印度的DTR将显著下降。这两种情景的差异凸显了全球气温升高和CO浓度升高对DTR以及某些地区生态系统的重大影响。
