Light absorbing impurity profiles in snow on sea-ice collected during SIPEX II

Particulate impurities in snow such as dust and soot can absorb sunlight. This is important for snow albedo in the Arctic, but probably not in the Antarctic. Snow was collected in plastic bags through the full depth of the snowpack over first-year sea ice at several locations: one location each on Ice Stations 1, 2, 3, 4, 7, upwind of the ship. The snow was melted and the meltwater filtered. The filters will be analysed for light-absorbing impurities in a laboratory spectrophotometer in Seattle. Samples of size ~1 kg were collected at Ice Station 1. The filters were blank, so at Ice Stations 2 and 3 larger samples of size 2-4 kg were collected. The filters were still blank, so at Ice Stations 4 and 7 larger samples of size ~8 kg were collected; these do show a slight darkening visible by eye. No snow samples were collected at Stations 5 and 6. Local (ship) time is UTC+10; Sun time is UTC+8. Filters are labelled with prefix 'AO' for Antarctic Ocean.This dataset currently contains snow density (except for at one ice station) and volumes of melt water that were filtered. No further analysis has been carried out on these samples at this point, however at a later stage the filters will be analysed for spectral absorption and converted to a mixing ratio of black carbon in the snow.积雪中的粉尘、炭黑等颗粒物杂质可吸收太阳光。这一效应对北极雪反照率（snow albedo）具有重要影响，但对南极而言可能并非如此。研究团队在船舶上风侧的多个一年海冰点位处，通过塑料袋采集了积雪剖面全层样品：冰站1、2、3、4、7各设置一个采样点位。将采集的积雪融化后，对融水进行过滤。后续将在西雅图的实验室分光光度计（spectrophotometer）中，对滤膜开展吸光杂质分析。冰站1采集了约1 kg的样品，但滤膜未检出杂质（呈空白状态）；因此冰站2和3调整采样量至2~4 kg，此时滤膜仍为空白；随后冰站4和7将采样量提升至约8 kg，此时肉眼可见滤膜出现轻微黑化。冰站5和6未采集积雪样品。本地（船舶）时间采用UTC+10，太阳时采用UTC+8。滤膜标签前缀‘AO’代表南大洋（Antarctic Ocean）。本数据集目前包含积雪密度（单个冰站除外）以及过滤后的融水体积数据。截至目前尚未对这些样品开展进一步分析，但后续将对滤膜进行光谱吸收特性分析，并将结果转换为积雪中黑碳（black carbon）的混合比。