Evolution of snow and firn on the Juneau Icefield, Alaska (2024)

Alpine glaciers of Alaska are a significant contributor to global sea-level rise. Most Alaskan glaciers lose mass through surface melting due to increasing atmospheric temperatures, which may change regional glacier hydrology, including firn properties and the firn's meltwater retention and runoff. We use field observations and firn modeling to investigate seasonal to decadal changes in the thermal and physical properties of firn on the Juneau Icefield, Alaska, and the impacts on the firn column’s capacity for refreezing meltwater. Our results reveal local and transient retention of liquid water in the snow and firn during the 2024 melt season. We also find that the long-term firn column’s capacity to refreeze liquid water (rain/melt) is decreasing due to decreasing firn cold content. The first dataset contains measurements collected during June and July of the 2024 field season at four sites on the Juneau Icefield (MLD, MG3, NWB1, and TKG4). These include density, permittivity, liquid-water content, and ablation rates. The documents "Juneau_Icefield_Firn_Core_Data_2024.csv" and "Juneau_Icefield_Ablation_Data_2024.csv" contain these data for all sites. The second dataset contains modeled results from using the Community Firn Model and the climate forcing used to run the model, including firn density, temperature, thickness, refreeze, and runoff, atmospheric temperature, snow accumulation, melt, and rainfall. The documents "mg3_model_results.csv," "mld_model_results.csv" and "nwb1_model_results" contain these data for the three sites in the accumulation zone (MLD, MG3, NWB1).阿拉斯加高山冰川是全球海平面上升的重要贡献因素之一。受大气温度升高影响，多数阿拉斯加冰川通过表面消融损失物质，这可能改变区域冰川水文过程，包括粒雪（firn）的属性、粒雪对融水的滞留与径流特征。本研究依托野外观测与粒雪模拟，探究阿拉斯加朱诺冰原（Juneau Icefield）粒雪的热学与物理性质在季节至年代际尺度上的变化，及其对粒雪柱融水再冻结能力的影响。研究结果显示，在2024年融冰季，积雪与粒雪中出现了局地性、暂时性的液态水滞留现象。本研究同时发现，由于粒雪冷含量持续降低，粒雪柱长期的液态水（降雨/融水）再冻结能力呈下降趋势。第一份数据集包含2024年野外科考季6月至7月期间，在朱诺冰原4个测点（MLD、MG3、NWB1及TKG4）获取的观测数据，涵盖密度、介电常数、液态水含量与消融速率。数据文件《Juneau_Icefield_Firn_Core_Data_2024.csv》与《Juneau_Icefield_Ablation_Data_2024.csv》收录了全部测点的上述观测数据。第二份数据集包含采用通用粒雪模型（Community Firn Model）开展的模拟结果，以及驱动模型运行的气候强迫数据，涵盖粒雪密度、温度、厚度、再冻结量与径流量，以及大气温度、积雪积累量、融水量与降雨量。数据文件《mg3_model_results.csv》、《mld_model_results.csv》与《nwb1_model_results》收录了积累区3个测点（MLD、MG3、NWB1）的上述模拟与强迫数据。