Snow depth, sea ice thickness and interface temperatures derived from measurements of SIMBA buoy 2013T2

The Snow and Ice Mass Balance Array (SIMBA) is a thermistor string type IMB (Jackson et al., 2013) which measures the environmental temperature SIMBA-ET and a temperature change around the thermistors after a weak heating is applied to each sensor (SIMBA-HT). SIMBA 2013T2 (a.k.a. Awi_21) is an autonomous instrument that was installed on drifting sea ice in the Antarctic Ocean (Polarstern PS81 (ANT29/6, AWECS) in 2013) as part of the project Sea Ice Physics @ AWI (AWI_SeaIce). Its thermistor chain is 5 m long, and equipped with 240 thermistors (Maxim Integrated DS28EA00) at a spacing of 2 cm. Based on a manual classification method, the SIMBA-ET and SIMBA-HT were processed to obtain snow depth and ice thickness (smoothed with a 3-day running mean), as well as the thermistor number, the vertical position Z relative to the snow-ice interface and the measured SIMBA-ET at each detected interface (atmosphere-snow, snow-ice and ice-ocean) for the period between 2013-07-08T15:00:39 and 2013-09-25T03:00:33. To do this, we combined two derivatives of measured temperatures (the ET vertical gradient and HT rise ratio) to reduce the detection uncertainty of all interfaces considered. The snow or ice surface, consequentially the snow depth, is determined by the ET vertical gradient. Potential formation of snow ice is not explicitly considered in this data set, but may occur as depicted by vertical changes of the snow-ice interface position. The ice-ocean interface is usually determined using the HT rise ratio and serves as the lower limit for ice thickness. Overall, the accumulated error is 2 to 4 times the sensor spacing for both the snow depth and ice thickness. For interface temperatures, individual sensors in the chain measure with a temperature resolution of 0.0625°C, with the overall accuracy landing in the range of ± 2°C (Jackson et al., 2013). After the snow cover has melted, negative values for snow depth may indicate the onset of ice surface melt.

冰雪质量平衡阵列（SIMBA）是一种热敏电阻串型冰质量平衡仪（IMB，Jackson等，2013），可测量环境温度（SIMBA-ET）以及对每个传感器施加弱加热后热敏电阻周围的温度变化（SIMBA-HT）。SIMBA 2013T2（又称Awi_21）是一款自主式仪器，2013年安装于南极海洋的漂流海冰上（德国极地科考船“极地stern”号PS81航次，ANT29/6，AWECS），作为阿尔弗雷德·韦格纳研究所（AWI）海冰物理项目（AWI_SeaIce）的一部分。其热敏电阻链长5米，配备240个热敏电阻（Maxim Integrated DS28EA00型号），间距为2厘米。基于手动分类方法，对SIMBA-ET和SIMBA-HT数据进行处理，以获取2013年7月8日15:00:39至2013年9月25日03:00:33期间的雪深和冰厚（经3日滑动平均平滑处理），以及每个检测界面（大气-雪、雪-冰、冰-海洋）处的热敏电阻编号、相对于雪-冰界面的垂直位置Z和实测SIMBA-ET值。为此，我们结合了实测温度的两个衍生指标（ET垂直梯度和HT上升比），以降低所考虑的所有界面的检测不确定性。雪面或冰面（进而雪深）由ET垂直梯度确定。本数据集未明确考虑雪冰的潜在形成，但雪-冰界面位置的垂直变化可能反映其形成。冰-海洋界面通常通过HT上升比确定，并作为冰厚的下限。总体而言，雪深和冰厚的累积误差均为传感器间距的2至4倍。对于界面温度，链中的单个传感器测量温度分辨率为0.0625°C，整体精度范围为±2°C（Jackson等，2013）。积雪融化后，雪深的负值可能表明冰表面融化的开始。