Physical and chemical analysis of firn cores from Ronne Ice Shelf, Antarctica

This data on the distribution of the accumulation rate and 18O content of near-surface layers in the eastern part of the Ronne Ice Shelf, Antarctica, were derived from an analysis of 16 firn cores. The firn cores were drilled along the traverse route of the Filchner-V-Campaign in 1995. The traverse followed an ice flowline of the Foundation Ice Stream and reached the margin of the inland ice, an area which has not yet been investigated. On the ice shelf the accumulation rates decrease with distance from the coast. Ascending to the inland ice the accumulation rates again reach almost coastal values. This regional distribution is in agreement with the temperature gradient along the traverse. The 18O content of the near-surface layers is closely related to the 10 m firn temperature. They strongly decrease from the grounding line towards the inland ice. At the southernmost site at 1100 m a.s.l., the mean d18O value of the firn decreases to -40‰. Ice with that isotopic signature was found in cores from the central part of the Ronne Ice Shelf just above the marine ice layer, indicating that it originates from this area. All ice deposited as snow further south was melted beneath the ice shelf after passing the grounding-line area. The time series of accumulation rate and 18O content reveal no climatic trend during the last 30-50 years.

本数据集涵盖南极龙尼冰架（Ronne Ice Shelf）东部近表层的积雪积累率与氧-18（18O）含量分布特征，其数据来源于对16根粒雪（firn）芯的分析。1995年，研究人员沿Filchner-V考察队（Filchner-V-Campaign）的考察航线钻取了这些粒雪芯，该航线沿Foundation冰流（Foundation Ice Stream）的冰流线（ice flowline）延伸，最终抵达内陆冰盖（inland ice）的边缘区域——该区域此前尚未被考察过。在龙尼冰架范围内，积雪积累率随距海岸距离的增加而逐渐降低；向内陆冰盖推进时，积累率又回升至接近海岸区域的水平，这一区域分布特征与考察航线沿线的温度梯度相符。近表层的氧-18含量与10米粒雪温度密切相关，其数值从冰架接地线（grounding line）向内陆冰盖方向显著降低。在海拔1100米的最南端测点，粒雪的平均δ18O值降至-40‰。在龙尼冰架中部紧邻海冰层（marine ice layer）上方的粒雪芯中，发现了具有该同位素特征的冰体，表明其源自该区域。所有在更南部区域以降雪形式沉积的冰体，在经过接地带区域后，于冰架下方发生消融。积雪积累率与氧-18含量的时间序列数据显示，过去30至50年间未出现显著的气候趋势。