The ice mass balance and CT package data of the buoy unmanned ice station collected in Arctic Ocean during the MOSAiC expedition 2019/2020@en

One unmanned ice station (UIS) has been deployed at the L3 site (85.13ºN, 135.68ºE) of the Distributed Network (DN) of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) campaign on 10 October 2019. The UIS is a new prototype of IMB assembled by the Polar Research Institute of China, which consists of two separate units (ice and ocean) to measure physical parameters of the air-snow-sea ice-ocean system. For the ice unit, two acoustic sensors (Campbell SR50A and Teledyne-Benthos PSA916, respectively) are used to measure the relative changes in the position of the air/snow and ice/water interfaces. Thermistors (Maxim Integrated DS28EA00) mounted at 0.03 m spacing along a 4.5-m thermistor chain were used to measure temperature profiles. Air temperature and relative humidity (Vaisala HMP155A), as well as barometric pressure (Vaisala CS106), were measured at 1.5 m height above the initial snow surface. The UIS ocean unit (CT package) consisted of five conductivity & temperature sensors (RBR duo CT), one conductivity, and temperature & depth (pressure) sensor (RBR concerto CTD). The ocean unit were used to measure upper ocean at the depths of about 5-40 m, with the initial depths of 5.4, 10.4, 15.4, 20.4, 25.4, and 40.4 m. The ice and ocean units of UIS were deployed 10 m apart. The initial ice thickness and snow depth at the buoy deployment site were 1.53 and 0.15 m, respectively. The changes in ice thickness was determined using measurements by the underwater acoustic sounder. The measuring noise of the acoustic sounder has been removed. Since the acoustic sensor at the surface was invalid very soon after the deployment, the evolution of the air/snow interface was determined using the temperature profiles. Overall, the measurement accuracy was 0.1 K for temperature, 0.03 m for the snow or ice surface, and 0.01 m for the ice bottom, respectively. After the snow cover melted over, the negative values for the snow depth indicate the onset of ice surface melt. The changes in the depths of CT sensors were estimated based on their initial depths and the depth measured by the CTD at the bottom of CT package. The measurement of the UIS ice unit lasted until 15 June 2020 when the buoy drifted to 82.28°N; while the ocean unit lasted until 28 September 2020 and finally failed at 74.09°N.2019年10月10日，一套无人冰站（unmanned ice station, UIS）部署于北极气候多学科漂流观测站（Multidisciplinary drifting Observatory for the Study of Arctic Climate, MOSAiC）项目的分布式观测网（Distributed Network, DN）L3站点（北纬85.13°，东经135.68°）。该无人冰站是中国极地研究中心组装的新型冰质量平衡浮标（Ice Mass Balance Buoy, IMB）原型样机，分为冰区与海洋区两个独立单元，用于观测气-雪-海冰-海洋系统的物理参数。冰区单元搭载两台声学传感器（分别为Campbell SR50A与Teledyne-Benthos PSA916），用以监测气/雪界面与冰/水界面的位置相对变化；沿4.5米热敏电阻链以0.03米间距布设的热敏电阻（Maxim Integrated DS28EA00）用于获取温度剖面数据。在初始雪面上方1.5米高度处，部署了维萨拉Vaisala HMP155A型空气温湿度传感器，以及维萨拉Vaisala CS106型气压传感器，以观测空气温度、相对湿度与大气压强。无人冰站的海洋单元（CT组件包）包含5台电导率-温度传感器（RBR duo CT），以及1台电导率、温度与深度（压强）传感器（RBR concerto CTD）。该海洋单元用于观测约5~40米深度的上层海洋，初始布设深度分别为5.4、10.4、15.4、20.4、25.4及40.4米。冰区与海洋单元的部署间距为10米。浮标部署点位的初始冰厚与雪深分别为1.53米与0.15米。冰厚变化通过水下声学测深仪的观测数据计算得到，且已剔除声学测深仪的测量噪声。由于表层声学传感器在部署后短期内即失效，气/雪界面的演化过程通过温度剖面数据反演得到。整体测量精度分别为：温度0.1 K，雪面或冰面0.03米，冰底0.01米。当积雪完全消融后，雪深出现负值时表征冰面融解过程启动。CT传感器的深度变化通过其初始布设深度与CT组件包底部的CTD实测深度估算得到。无人冰站的冰区单元观测持续至2020年6月15日，彼时该浮标漂移至北纬82.28°；海洋单元观测则持续至2020年9月28日，最终在北纬74.09°处失效。