全球地表气温日较差长期趋势的演化特征

Study on the Evolution Characteristics of the Long-term Trend of Global Surface Diurnal Temperature Range

基于多维集合经验模态分解方法,利用CRU全球地表气温日较差、最高气温和最低气温资料,开展对1951~2019年全球地表气温日较差长期趋势的演化研究。结果表明:全球地表气温日较差主要呈现下降趋势,并以北半球中高纬度地区为甚,空间差异性较大。全球地表最高气温和最低气温的长期演化趋势则主要表现为上升,且最低气温更为剧烈。从纬向平均的角度看,全球地表气温日较差长期趋势主要存在五条负值带,降低趋势在北半球逐渐加强,并存在与之相伴随的冷舌,而在南半球呈先增强后减弱的特征。由瞬时演化速率可知,全球地表气温日较差长期趋势下降的速率整体上趋于减缓,并于后期在澳洲北部、地中海沿岸以及南美洲南部等地转为上升趋势。

Based on the multidimensional ensemble empirical mode decomposition(MEEMD)method,the long-term evolution of global land surface diurnal temperature range(DTR)trend from 1951 to 2019 was explored by using the Climate Research Unit(CRU)dataset.The results show that the diurnal variation of global surface temperature shows a downward trend,especially in the middle and high latitudes of the Northern Hemisphere(NH),and the spatial variability is considerable.The long-term evolution of global land maxim-um and minimum temperatures trends are mainly increasing,and the latter is more drastic.From the perspective of zonal averaged,five main negative bands of DTR are found.The decreasing trend gradually strengthens in NH,with accompanying cold tongues,while charac-teristic in the Southern Hemisphere shows strengthening first and then weakening.The instantaneous rate reveals the fact that the decrease rate of global DTR trends tends to slow down overall and turns positive in regions such as northern Australia,the Mediterranean coast,and southern South America in recent decades.