摘要
海冰最早开始融化时间(EMO)是体现海冰融化的重要指标,也是影响海冰热收支的关键因素。本文使用EMO遥感数据、ERA5再分析资料和海冰密集度数据分析研究了地表气温和液态降水对EMO影响的相对贡献。研究显示,在5个研究海区中,大西洋扇区南区EMO提前最显著,1979-2021年的变化率为-3.3 d/(10 a)。北极各海区的地表气温与EMO有着持续1~2个月的显著相关时段,其中太平洋扇区南区、大西洋扇区北区和南区的地表气温较液态降水与EMO相关的持续时间更长,相关性也更强;而对太平洋扇区北区和北极中央区,只有在EMO发生前的2~3周,液态降水对其EMO有着更高的贡献。对于太平洋扇区北区,大气环流提供的强水汽输送通道伸入该海区,使对流层低层饱和水汽增多,500 hPa位势高度的多年变化趋势具有三波绕极环流加强的结构,也有利于经向的热量交换,使比湿的垂向梯度进一步增加,为该海区EMO的提前起到一定的促进作用。对于北极中央区,在EMO提前的年份,液态降水较常年偏高33%,不仅气候态意义下的太平洋水汽通道的输送加强,欧亚大陆上空的水汽通道也与之汇合,促使北极东部形成气旋式水汽输送模态,为EMO的提前发生提供了有利条件。
Early melt onset(EMO)is a crucial time index for sea ice melting and has a significant impact on the thermal balance of sea ice.In this paper,EMO remote sensing,ERA5 reanalysis,and sea ice concentration data have been used to reveal the relative contribution of surface air temperature and liquid precipitation.Our research indicates that,the most significant advancement of EMO is observed in the southern Atlantic sector among the five study sea areas from 1979-2021,with the rate of-3.3 d/(10 a).For the atmospheric factors affecting EMO,surface air temperature has a considerable correlation period lasting 1-2 months with EMO in all Arctic sea areas.In addi-tion,surface air temperature in the southern Pacific sector and northern and southern Atlantic sectors have a longer duration and stronger correlation with EMO than liquid precipitation.However,for the northern Pacific sector and the central Arctic,liquid precipitation has a higher contribution only in the 2-3 weeks prior to EMO.For the north-ern Pacific sector,atmospheric circulation provides strong water vapor transport channel extends into this sea area,increasing saturated water vapor in the lower troposphere.Meanwhile,the trend of the 500 hPa potential height shows a three-wave strengthening atmospheric circulation structure around the pole,allowing meridional heat ex-change and enhancing the vertical gradient of specific humidity,which promotes the advancement of EMO.For the central Arctic,in years when EMO is advanced,the liquid precipitation is 33%higher than climatology.Addition-ally,not only the Pacific water vapor transport in the climatology is enhanced,but also the converges with water va-por channel over Eurasia continent,contributing to the formation of cyclonic water vapor transport mode in the east-ern Arctic,providing conditions for the advancement of EMO.
作者
周璇
苏洁
Zhou Xuan;Su Jie(College of Oceanography and Atmosphere,Ocean University of China,Qingdao 266100,China;Key Laboratory of Physical Oceano-graphy,Ministry of Education,Ocean University of China,Qingdao 266100,China;Joint Center for Polar Research of Chinese Uni-versities,Beijing 100875,China)
出处
《海洋学报》
CAS
CSCD
北大核心
2023年第9期10-24,共15页
基金
国家自然科学基金(42076228)
国家自然科学专项基金(41941012)。
关键词
海冰最早开始融化时间
液态降水
地表气温
相对贡献
early melt onset of sea ice
liquid precipitation
surface air temperature
relative contribution
