北极海冰厚度的热力学和动力学影响因素研究评述

Overview on the thermodynamic and dynamic factors influencing Arctic sea ice thickness

全球变化背景下,在过去的40年中,北极海冰范围快速减少,厚度显著变薄,同时多年冰向一年冰转化,这对区域乃至全球气候系统具有重要影响。海冰厚度作为气候变化的指示器,在大气-海冰-海洋之间的物质和能量交换过程中起着重要作用。本文通过综述国内外北极海冰厚度影响因子的研究进展,对影响北极海冰厚度的热力学和动力学过程进行了梳理和总结。在热力学方面,海冰厚度会受到大气-海冰和海冰-海洋两个界面处的热通量影响,其中,大气-海冰热力学过程的影响因素包括冰面特征、气温、水汽、降雨/降雪和云量等,主要通过海冰表面辐射收支和湍流热交换(感热和潜热)产生影响;而海冰-海洋界面处的热通量作为海冰厚度的重要影响因素,主要受太阳辐射对上层海洋的加热、风应力导致的垂向混合以及中低纬暖流输送的影响。在动力学方面,海冰厚度变化主要通过风和海流的共同驱动引起海冰输运和海冰的形变。大尺度环流异常也会通过大气-海冰-海洋相互作用对北极冰厚的热力学和动力学过程产生显著影响。

Under current climate change conditions,Arctic sea ice has become a key scientific topic,because of its close connection with global climate.Sea ice thickness,important for material and energy exchanges between the atmosphere,sea ice and oceans,is also an indicator of climate change.In the last 40 years,Arctic sea ice cover has rapidly shrunk,ice thickness has markedly decreased,and ice melt has strongly accelerated.These changes have markedly affected the climate system at the regional and global scale.Summarizing previous research results,this paper comprehensively describes the thermodynamic and dynamic processes affecting Arctic sea ice thickness.Thermodynamically,sea ice thickness is affected by atmospheric variables including ice characteristics,air temperature,water vapor,rainfall,snowfall and cloud cover,through the sea ice surface radiation budget and turbulent heat exchange(sensible and latent heat).Moreover,the ocean heat flux affecting sea ice thickness results from upper ocean heating by solar radiation,vertical mixing induced by wind stress,and warm water input from middle and low latitudes.Dynamically,the interaction between wind stress and ocean currents generates sea ice transport and deformation,thereby affecting the sea ice thickness.In summary,climate variability induces additive forcing from these thermodynamic and dynamic processes on sea ice thickness variation.