雪冰反馈对北半球经向温度梯度的影响

Impact of the Ice-albedo Feedback on Meridional Temperature Gradient of Northern Hemisphere

利用观测资料分析了近百年北半球陆地中、高纬的经向温度梯度变化,发现高纬的经向温度梯度有明显的增大趋势,而CMIP5模式的模拟结果却呈显著减小的趋势。本研究表明,这主要是由于CMIP5模式中夸大了高纬地区局地雪冰反馈过程对增温的贡献。利用一维能量平衡模式,通过一系列模拟试验,研究了雪冰反馈过程对增温和经向温度梯度变化的影响。结果表明,在仅由CO2变化导致的气候增暖过程中,考虑雪冰反馈后增温的幅度较大,并且高纬的增温比低纬更显著;在气候增暖过程中,雪冰反馈对低纬的经向温度梯度影响很小,但对高纬的经向温度梯度减小有促进作用。

This paper analyzes the variation of meridiona] temperature gradient （MTG） over mid-latitude and high-latitude of Northern Hemisphere continents during last 100 years using observational data. It is found that MTG over high-latitude of Northern Hemisphere continents has an increasing trend, but the simulation results of CMIP5 models show a decreasing trend. Results of this study showed the decrease of MTG over the high-latitude continents of Northern Hemisphere calculated by CMIP5 historical simulations mainly because the models of CMIP5 exaggerat- ed ice-albedo feedback over high-latitude regions. A series of simulation results by energy balance climate models showed that ice-albedo feedback amplified the magnitude of warming in the global warming induced only by carbon dioxide, and the magnitude of warming in high-latitude was much larger than that in low-latitude regions. Along with global warming, ice-albedo feedback has little influence on MTG in low-latitude, but can induce the decrease of MTG in high-latitude regions.