北极巴罗地区海冰消融初期表面特征及光谱反射率观测研究

北极海冰消融初期，上覆积雪急剧消融，融池开始形成，海冰表面物理特征异常复杂。由于观测资料缺乏，对这一时期海冰变化的研究仍存在较大不确定性。利用2015年5月份在巴罗Elson Lagoon海域观测的海冰表面物理特征和光谱反射率数据，分析了巴罗地区海冰消融初期表面积雪、裸冰和融池反射率特性及其影响因素。结果表明：消融初期，海冰表面异质性强，积雪、裸冰和融池相间分布。在积雪覆盖的区域，积雪对海冰光谱反射率起决定性作用，观测到不同雪深（3~23 cm）的反射率变化在0.53~0.85之间，平均反射率为0.76且反射率与雪深呈正相关。在表面积雪厚度相同的情况下，积雪底层含水量越大，表层反射率越小。观测还显示，在融池形成的区域，海冰的反射率急剧降低，融池初形成时反射率为0.206，略低于裸冰（0.216）。随着融池的发展，当其深度达到10 cm时，反射率仅为0.04，与开阔海域海水接近。

Measurements of the surface features and the reflectance of Arctic sea ice during the initial phase of the melt season in Barrow

In the initial phase of the melt season of the Arctic sea ice,the overlying snow melts dramatically and the melt ponds begin to form,resulting in complicated physical characteristics of sea ice surface.Due to lack of observational data,there are still large uncertainties in the study of sea ice changing during this period.In this study,the physical features and spectral reflectance on the surface of the sea ice in Elson Lagoon ocean area at Barrow,Arctic were observed in May 2015.The reflectances of surface snow cover,bare ice and melt ponds at the early ablation stage of sea ice were analyzed and the potential influence factors were also explored.The results showed that in the initial phase of the melt season,the heterogeneity of sea ice surface was significant with alternate distribution of snow cover,bare ice and melt ponds.In snow cover area,snow played a decisive role on sea ice reflectance.The observed reflectances at different snow depths (3 ～23cm) ranged between 0.53 and 0.85,positively correlated with snow depth.For the areas with same snow depth,higher water content of the bottom would lead to smaller surface reflectance.Observations also showed that sea ice reflectance decreased dramatically at the melt pond area,reaching 0.206 at the beginning formation period of the melt ponds,which was slightly lower than the reflectance of bare ice,0.216.The reflectance would decrease with the development of the melt ponds and approach to that in open water when the depth of the melt ponds reached 10 cm.