Changes in temperature and heat waves over Africa using observational and reanalysis data sets
Changes in temperature and heat waves over Africa using observational and reanalysis data sets
复制标题
DOI：
10.1002/joc.7295
复制
发表时间：
2021-08-03
期刊：
影响因子：
--
通讯作者：
Steiner, Andrea K.
中科院分区：
文献类型：
--
作者：
Engdaw, Mastawesha Misganaw;Ballinger, Andrew P.;Steiner, Andrea K.
提供关于在气候系统中观测到的变化的全面的区域和地方尺度的信息，对于规划有效和高效的气候变化适应备选办法，特别是在资源有限的区域，发挥着至关重要的作用。在这里，我们评估了非洲大陆不同地区的温度和热浪的变化，重点是时空趋势和自然变异性极端高温变化的出现时间。我们分析了绝对和相对阈值指标。数据集包括来自观测（CRUTS4.03和BEST）和1980-2018年共同时期的三个代表性最先进的再分析（ERA 5，MERRA 2和JRA-55）的温度。根据CRU的观测和再分析数据，在非洲所有地区的温度时间序列中都观察到了统计上显著的变暖，尽管不同数据集的趋势强度不同。此外，BEST观测和所有再分析数据集的极端温度和热浪指数显示，非洲大陆所有区域的极端温度和热浪指数都呈上升趋势。但是，不同再分析数据集的热浪指数在趋势强度和时间演变上存在差异。大多数数据集一致认为，2010年是北方和西部非洲的最热年份，而东部和南部非洲在2016年经历了最高的热浪发生。我们的研究结果清楚地表明，热浪的发生源于非洲的自然气候变化。北方非洲地区最早出现的时间是2000年代初，而其他非洲地区出现自然变异的时间主要是在2010年之后。这也取决于相应的指数指标，其中基于更连续天数的指数显示热浪趋势的出现较晚。总体而言，非洲所有区域都出现了明显的变暖和热浪发生率的增加，这是过去一、二十年来自然变化造成的。
Providing comprehensive regional- and local-scale information on changes observed in the climate system plays a vital role in planning effective and efficient climate change adaptation options, specifically over resource-limited regions. Here, we assess changes in temperature and heat waves over different regions of the African continent, with a focus on spatiotemporal trends and the time of emergence of change in hot extremes from natural variability. We analyse absolute and relative threshold indices. Data sets include temperatures from observations (CRUTS4.03 and BEST) and from three representative state-of-the-art reanalyses (ERA5, MERRA2 and JRA-55) for the common period 1980-2018. Statistically significant warming is observed over all regions of Africa in temperature time series from CRU observations and reanalysis data, although the trend strength varies between data sets. Also, extreme temperatures and heat wave indices from BEST observations and all reanalysis data sets reveal increasing trends over all regions of the African continent. However, there are differences in both trend strength and time evolution of heat wave indices between different reanalysis data sets. Most data sets agree in identifying 2010 as a peak heat year over Northern and Western Africa while Eastern and Southern Africa experienced the highest heat wave occurrence in 2016. Our results clearly reveal that heat wave occurrences have emerged from natural climate variability in Africa. The earliest time of emergence takes place in the Northern Africa region in the early 2000s while in the other African regions emergence over natural variability is found mainly after 2010. This also depends on the respective index metrics, where indices based on more consecutive days show later emergence of heat wave trends. Overall, significant warming and an increase in heat wave occurrence is found in all regions of Africa and has emerged from natural variability in the past one or two decades.