Specific surface area of surface snow along a traverse route between a coastal base near Syowa Station and Dome Fuji in East Antarctica from November 2021 to January 2022

To better understand the surface properties of the Antarctic ice sheet, we measured the specific surface area (SSA) of surface snow during two round-trip traverses between a coastal base near Syowa Station, located 15 km inland from the coast, and Dome Fuji, located 1066 km inland, in East Antarctica from November 2021 to January 2022. Using a handheld integrating sphere snow grain sizer (HISSGraS), which directly measures snow surface without sampling, we collected 215 sets of SSA data, each set comprising measurements from 10 surfaces along a 20 m transect. The measured SSA shows no elevation or temperature dependence at 15-500 km from the coast at elevations of 615-3000 m, with a mean and standard deviation of 25 +- 9 m^2 kg^-1. Beyond this area, SSA increases toward the interior, reaching 45 +- 11 m^2 kg^-1 between 800 and 1066 km from the coast, at elevations of 3600-3800 m. SSA shows no significant systematic differences between the traverses but changes dynamically depending on surface morphologies and short-term meteorological events. This includes that: (i) glazed surfaces, an accumulation-hiatus form appeared in katabatic wind areas, show low SSA (19 +- 4 m^2 kg^-1), decreasing the mean SSA and increasing SSA variability in the areas. (ii) Snow deposition increases surface snow SSA to 60-110 m^2 kg^-1, but it is inhibited by snow drifting at wind speeds above 5 m s^-1. Our analyses for these observations clarified that temperature-dependent snow metamorphism, snowfall frequency, and wind-driven inhibition of snow deposition play crucial roles in the spatial variation of surface snow SSA in the Antarctic inland. The extensive dataset will enable the validation of satellite-derived and model-simulated SSA variations across Antarctica.

为更好地理解南极冰盖的表面特性，我们于2021年11月至2022年1月期间，在东南极洲开展了两次往返考察：从距离海岸15公里内陆的昭和站（Syowa Station）附近的沿海基地，前往位于内陆1066公里处的富士冰穹（Dome Fuji），并在此期间测量了表层雪的比表面积（specific surface area, SSA）。我们采用手持式积分球雪粒分析仪（Handheld Integrating Sphere Snow Grain Sizer, HISSGraS）开展测量，该设备无需采样即可直接测定雪层表面特性，共获取了215组比表面积数据。每组数据包含沿20米样带的10个表面测点的测量结果。所测得的比表面积在距离海岸15至500公里、海拔615至3000米的区域内，未表现出与海拔或温度的相关性，其平均值与标准差为25±9 m²·kg⁻¹。在此区域之外，比表面积向内陆逐渐升高，在距离海岸800至1066公里、海拔3600至3800米的区域内达到45±11 m²·kg⁻¹。两次考察的比表面积测量结果未出现显著的系统性差异，但会随表面形貌与短期气象事件动态变化。具体表现为：（i）在下降风（katabatic wind）区域出现的积雪停滞型光滑表面，其比表面积较低（19±4 m²·kg⁻¹），会降低该区域的平均比表面积并增大其离散程度；（ii）降雪过程会使表层雪的比表面积升高至60~110 m²·kg⁻¹，但当风速超过5 m·s⁻¹时，吹雪过程会抑制这一效应。针对上述观测结果的分析表明，依赖温度的雪层变质作用、降雪频率以及风力对积雪过程的抑制作用，是南极内陆表层雪比表面积空间分布差异的关键驱动因素。本次构建的大规模数据集，可用于验证南极地区卫星反演与模型模拟得到的比表面积变化结果。