Ice and snow measurements during Nathaniel B. Palmer cruise NBP0709 (SIMBA experiment)

The Sea Ice Mass Balance in the Antarctic (SIMBA) experiment was conducted from the RVIB N.B. Palmer in September and October 2007 in the Bellingshausen Sea in an area recently experiencing considerable changes in both climate and sea ice cover. Snow and ice properties were observed at 3 short-term stations and a 27-day drift station (Ice Station Belgica, ISB) during the winter-spring transition. Repeat measurements were performed on sea ice and snow cover at 5 ISB sites, each having different physical characteristics, with mean ice (snow) thicknesses varying from 0.6 m (0.1 m) to 2.3 m (0.7 m). Ice cores retrieved every five days from 2 sites and measured for physical, biological, and chemical properties. Three ice mass-balance buoys (IMBs) provided continuous records of snow and ice thickness and temperature. Meteorological conditions changed from warm fronts with high winds and precipitation followed by cold and calm periods through four cycles during ISB. The snow cover regulated temperature flux and controlled the physical regime in which sea ice morphology changed. Level thin ice areas had little snow accumulation and experienced greater thermal fluctuations resulting in brine salinity and volume changes, and winter maximum thermodynamic growth of ~0.6 m in this region. Flooding and snow-ice formation occurred during cold spells in ice and snow of intermediate thickness. In contrast, little snow-ice formed in flooded areas with thicker ice and snow cover, instead nearly isothermal, highly permeable ice persisted. In spring, short-lived cold air episodes did not effectively penetrate the sea ice nor overcome the effect of ocean heat flux, thus favoring net ice thinning from bottom melt over ice thickening from snow-ice growth, in all cases. These warm ice conditions were consistent with regional remote sensing observations of earlier ice breakup and a shorter sea ice season, more recently observed in the Bellingshausen Sea.

南极海冰质量平衡（Sea Ice Mass Balance, SIMBA）实验于2007年9月至10月期间，搭乘N.B.帕尔默号研究船（RVIB N.B. Palmer）在别林斯高晋海实施，该海域近期正经历气候与海冰覆盖的显著变化。在冬春转换期，研究团队于3个短期观测站与1个为期27天的漂流冰站——贝尔吉卡冰站（ISB）——开展了雪冰属性观测。研究人员在5个具备不同物理特征的贝尔吉卡冰站点位开展了重复观测，这些点位的平均冰（雪）厚度范围为0.6米（0.1米）至2.3米（0.7米）。研究团队于2个点位每5天获取冰芯，并对其物理、生物与化学属性开展检测。3台海冰质量平衡浮标（IMBs）持续记录了积雪与海冰厚度及温度数据。贝尔吉卡冰站观测期间，气象条件历经四个完整循环：先出现伴随强风与降水的暖锋，随后转为寒冷平静的时段。积雪调节了热通量，并主导了海冰形态演变的物理过程。平坦薄冰区积雪积累量极少，且热波动更为显著，进而导致盐水盐度与体积发生变化；该区域冬季最大热力学冰厚增长约0.6米。中等厚度的海冰与积雪区域在寒冷时段会发生海水漫溢与雪冰形成事件。与之相反，厚冰与厚积雪覆盖的漫溢区域几乎未形成雪冰，反而以近乎等温、高渗透性的冰体持续存在。春季时段，短暂的冷空气活动既无法有效穿透海冰，也无法抵消海洋热通量的影响，因此在所有观测点位，海冰底部融化导致的净减薄程度均超过雪冰生长带来的增厚幅度。这类暖冰环境与别林斯高晋海近期遥感观测到的海冰提前解体、海冰存续期缩短的现象相一致。