Measurements of the surface features and the reflectance of Arctic sea ice during the initial phase of the melt season in Barrow
AN Hongmin;DOU Tingfeng;CHE Tao;XIAO Cunde;DU Zhiheng;State Key Laboratory of Cryospheric Sciences,Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences;Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences;University of Chinese Academy of Sciences;Chinese Academy of Meteorological Sciences;
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 and0. 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.