2008年夏季北冰洋海冰表面积雪特征初步分析

运用中国第三次北极考察期间观测的积雪资料, 分析了夏季北冰洋中心海域海冰表面积雪的空间分布特征. 结果表明: 积雪在垂直分布上呈现6种粒雪状态, 表层到底层依次为新降雪、风板、冰片、深霜、冻结状粗雪和渗浸冻结冰层, 积雪表面常被新降雪或厚度为2～3 cm的风板所覆盖. 考察区域积雪的平均密度为(304.01±29.00)kg·m^-3, 表层密度略低于次表层, 遵循雪的密实化原理. 积雪厚度, 雪水当量和新降雪皆具有由南向北递减的空间分布特征, 表明在海冰消融末期, 积雪的气候态分布主要是由降水量的多少决定的, 积雪的消融和蒸发并非海冰表面积雪评估需考虑的首要因素. 雪温随深度的增加而增加, 具有明显的垂直梯度, 观测区积雪表面的平均温度为(-2.01～±0.96)℃, 比海冰/积雪界面的温度高得多.

Analysis on Features of Snow Cover on the Arctic Sea Ice in Summer of 2008

In this study,the distribution of snow cover on the sea ice surface in the Arctic summer is analyzed using the observations during the 3rd Chinese Arctic Expedition.It is found that there are six firn statuses within the snow cover from surface to bottom along the Arctic cruise.They are new snow,wind crust,ice slice,depth hoar,frozen coarse snow and infiltration-congelation ice.Snow surface is often covered by new snow or wind crust,2～3 cm in depth.Mean snow density is(304.01±29.00)kg·m-3,and surface snow density is always smaller than the subsurface snow density,owing to snow densification.Snow depth,snow water equivalent and new snow amount decrease gradually from south to north,indicating the climate over snow cover is mainly controlled by precipitation.Therefore,melting and evaporation are not the principal factors that should be taken into account in the assessment of snow cover at the end of the Arctic summer.There is a distinct vertical gradient in snow temperature profile;the mean temperature at snow surface is-2.01～0.96 ℃,much higher than the temperature in the interface between snow and sea ice.