全球变暖过程中海陆增温差异特征研究进展

Research Review on the Contrast of Land and Ocean Warming Features Under the Global Warming

全球变暖过程中,陆表平均升温幅度显著大于海表,即海陆增温差异现象。随着全球气温持续升高,海陆气温增幅的差异不断增大,但海陆增温比基本保持恒定,海陆增温比最大出现在中高纬地区。本文总结了全球变暖过程中海陆增温差异现象的研究现状,从气候系统对温室气体等外强迫的瞬时响应和平衡态响应两个角度介绍海陆增温差异的形成机制。结果表明:海陆热容量差异是海陆增温差异形成的原因之一,而大气湿度与垂直减温率反馈是造成海陆增温差异的主要原因,且海表温度强迫和植被蒸腾、地表蒸发、云量、降水和相对湿度的变化对海陆增温差异的形成有一定贡献。模式模拟的海陆增温比与观测结果基本一致,但在北半球中高纬度地区被严重低估,这可能与常绿针叶林扩张引起的反照率反馈和阻塞高压与海陆热力差异之间的反馈有关。

Under global warming, the mean warming trend over land surface was much faster than that over ocean surface, therefore, there was difference of warming between land and ocean. As the increase of global mean surface air temperature, the difference between land and ocean warming also gradually increased, but the warming ratio between land and ocean was nearly constant, and it was the maximum in mid-high latitude of the Northern Hemisphere. The current situation of researches on land-ocean warming contrast under global warming was summarized and reviewed in this paper. The transient and equilibrium responses of climate system to external forcing such as greenhouse gases were investigated to explore the mechanism of land-ocean warming contrast. The results show that the difference of heat capacity between land and ocean was not main reason, while the atmospheric humidity and lapse rate feedback was main reason of land-ocean warming contrast, and SST forcing and change of vegetation evapotranspiration, surface evaporation, cloud amount, precipitation and relative humidity all contributed to the land-ocean warming contrast in short time scale. The simulated land-ocean warming ratio was basically consistent with the observations. However, it was excessively underestimated in mid-high latitude of the Northern Hemisphere, which might be related to the feedback of albedo induced by evergreen broad-leave forest expansion and between blocking and land-sea thermal contrast.