春季北极地区云量年际变化特征及其对北极放大反馈的作用

Interannual Variation of Spring Cloud Cover in Arctic and Its Effect on Arctic Amplification Feedback

摘要: 本文基于2000~2017年CERES云量资料对春季北极地区低、中、高云量进行多变量–经验正交函数分解(MV-EOF)，发现前两模态云量均存在较强的年际变化特征。第一模态显著信号位于在大西洋扇区的格陵兰海–巴伦支海，低云量异常偏少，高云异常偏多，产生云辐射冷却效应，与北极放大增暖效应相互抵消，表层温度变化小。太平洋扇区的喀拉海–拉布捷夫海以及北冰洋中心高低空云量一致增加，这种云量变化特征的产生云辐射效应对该区域表层能量平衡贡献较小；第二模态显著性信号位于除了格陵兰海–巴伦支海以外的北冰洋上空，低云量异常偏多，高云异常偏少，但是中高云变化不明显。这种云量变化会产生较强的云长波辐射加热效应，增强北极放大反馈。

Abstract: Based on CERES cloud cover, radiation data and ERA-Interim reanalysis data from 2000-2017 period, obvious interannual variations of spring cloud cover are found in the top two modes by multivariate empirical orthogonal function (MV-EOF) decomposition. The significant signal is located in the Greenland Sea-Barents Sea in the Atlantic sector with negative low cloud anomaly and positive high cloud anomaly in first mode. Cloud radiative cooling effect is generated and offsets warming effect of Arctic amplification, so surface temperature has no evident change. The cloud cover in the Kara sea-Laptev sea of the Pacific sector and the center of the Arctic Ocean increases uniformly. The significance signal of the second mode is located over the Arctic Ocean except the Greenland Sea-Barents Sea with positive low cloud anomaly and negative high cloud anomaly, but high cloud change is not obvious. Such cloud cover change can produce strong cloud longwave radiative heating effect and enhance the sea ice-albedo positive feedback and arctic amplification feedback.