Changes in the daily maximum (Tmax) and minimum (Tmin) surface air temperatures and the associated temperature extremes have severe consequences on human society and the natural environment. In this study, we assess v...Changes in the daily maximum (Tmax) and minimum (Tmin) surface air temperatures and the associated temperature extremes have severe consequences on human society and the natural environment. In this study, we assess vegetation effects on mean Tmax and Tmin over China by computing a vegetation feedback parameter using the satellite-sensed Normalized Difference Vegetation Index (NDVI) and observed temperatures for the period 1982–2002. In all seasons, vegetation exerts a much stronger forcing on Tmax than on Tmin, and thus has a substantial effect on the diurnal temperature range (DTR) over China. Significant positive feedbacks on Tmax and the DTR occupy many areas of China with the feedback parameters exceeding 1°C (0.1 NDVI)–1, while significant negative effects only appear over the summertime climatic and ecological transition zone of northern China and some other isolated areas. Also, the vegetation feedbacks are found to vary with season. In areas where significant feedbacks occur, vegetation contributes to typically 10%–30% of the total variances in Tmax, Tmin, and the DTR. These findings suggest that vegetation memory offers the potential for improving monthly-to-seasonal forecasting of Tmax and Tmin, and the associated temperature extremes over China. Meanwhile, the limitations and uncertainties of the study should be recognized.展开更多
准确理解地质历史时期气候变化的现象和机制,对预测未来气候变化有重要的启示意义。末次间冰期早期是研究未来气候变化可参考的典型暖期。目前,基于气候模式模拟的末次间冰期早期温度低于气候记录重建的结果。这一现状的一个潜在原因在...准确理解地质历史时期气候变化的现象和机制,对预测未来气候变化有重要的启示意义。末次间冰期早期是研究未来气候变化可参考的典型暖期。目前,基于气候模式模拟的末次间冰期早期温度低于气候记录重建的结果。这一现状的一个潜在原因在于,这些气候模拟研究中采用的植被数据为工业革命前水平,忽略了植被动态对气候的反馈作用。本研究利用iLOVECLIM气候模式耦合植被模块VECODE和LPJ-GUESS开展末次间冰期早期(125 ka B. P.)植被动态对气候反馈作用的模拟分析。模拟结果显示,相比基于工业革命前植被条件模拟得到的温度水平,耦合动态植被模拟的全球气候更温暖,但仍略低于记录重建的温度。在大陆/亚大陆尺度,高纬和北非地区模拟的125 ka B. P.植被覆盖度明显高于工业革命前水平,增温幅度也显著高于其他地区;此外,末次间冰期早期北非植被覆盖对区域气温的正反馈通过增强的大气环流使低纬地区输送到高纬地区热量增加,从而表现出对全球气温的正反馈作用。展开更多
Studying the vegetation feedback during warm periods of the past can lead to better understanding of those in the future.In this study,we conducted several simulations to analyze vegetation feedback during the mid-Pli...Studying the vegetation feedback during warm periods of the past can lead to better understanding of those in the future.In this study,we conducted several simulations to analyze vegetation feedback during the mid-Pliocene warm period.The results indicate that the main features of vegetation change in the mid-Pliocene were a northward shift of needleleaf tree,an expansion of broadleaf tree and shrub,and a northward expansion of grass,as compared to the pre-industrial period.The global annual mean warming ratio caused by vegetation feedback was 12.1％,and this warming ratio was much larger in northern middle and high latitudes.The warming caused by vegetation change was directly related to the surface albedo change and was further amplified by snow/sea ice-albedo feedback.展开更多
基金supported by the Hundred Talent Program of the Chinese Academy of Sciencesthe Special Fund for President’s Prize of the Chinese Academy of Sciencesthe National Basic Research Program of China (2009CB421405)
文摘Changes in the daily maximum (Tmax) and minimum (Tmin) surface air temperatures and the associated temperature extremes have severe consequences on human society and the natural environment. In this study, we assess vegetation effects on mean Tmax and Tmin over China by computing a vegetation feedback parameter using the satellite-sensed Normalized Difference Vegetation Index (NDVI) and observed temperatures for the period 1982–2002. In all seasons, vegetation exerts a much stronger forcing on Tmax than on Tmin, and thus has a substantial effect on the diurnal temperature range (DTR) over China. Significant positive feedbacks on Tmax and the DTR occupy many areas of China with the feedback parameters exceeding 1°C (0.1 NDVI)–1, while significant negative effects only appear over the summertime climatic and ecological transition zone of northern China and some other isolated areas. Also, the vegetation feedbacks are found to vary with season. In areas where significant feedbacks occur, vegetation contributes to typically 10%–30% of the total variances in Tmax, Tmin, and the DTR. These findings suggest that vegetation memory offers the potential for improving monthly-to-seasonal forecasting of Tmax and Tmin, and the associated temperature extremes over China. Meanwhile, the limitations and uncertainties of the study should be recognized.
文摘准确理解地质历史时期气候变化的现象和机制,对预测未来气候变化有重要的启示意义。末次间冰期早期是研究未来气候变化可参考的典型暖期。目前,基于气候模式模拟的末次间冰期早期温度低于气候记录重建的结果。这一现状的一个潜在原因在于,这些气候模拟研究中采用的植被数据为工业革命前水平,忽略了植被动态对气候的反馈作用。本研究利用iLOVECLIM气候模式耦合植被模块VECODE和LPJ-GUESS开展末次间冰期早期(125 ka B. P.)植被动态对气候反馈作用的模拟分析。模拟结果显示,相比基于工业革命前植被条件模拟得到的温度水平,耦合动态植被模拟的全球气候更温暖,但仍略低于记录重建的温度。在大陆/亚大陆尺度,高纬和北非地区模拟的125 ka B. P.植被覆盖度明显高于工业革命前水平,增温幅度也显著高于其他地区;此外,末次间冰期早期北非植被覆盖对区域气温的正反馈通过增强的大气环流使低纬地区输送到高纬地区热量增加,从而表现出对全球气温的正反馈作用。
基金supported by the Strategic Priority Research Program (Grant No.XDB03020602) of the Chinese Academy of Sciencesthe National Natural Science Foundation of China (Grant Nos. 41175072, 41222034 and 41305073)
文摘Studying the vegetation feedback during warm periods of the past can lead to better understanding of those in the future.In this study,we conducted several simulations to analyze vegetation feedback during the mid-Pliocene warm period.The results indicate that the main features of vegetation change in the mid-Pliocene were a northward shift of needleleaf tree,an expansion of broadleaf tree and shrub,and a northward expansion of grass,as compared to the pre-industrial period.The global annual mean warming ratio caused by vegetation feedback was 12.1％,and this warming ratio was much larger in northern middle and high latitudes.The warming caused by vegetation change was directly related to the surface albedo change and was further amplified by snow/sea ice-albedo feedback.
