A thermistor string-based snow and ice mass balance apparatus (SIMBA) was deployed in the land-fast sea ice zone in Young sound, eastern Greenland, on 28 October 2020, and operated successfully until 10 April 2021. The SIMBA was manufactured by the Scottish Association for Marine Science (SAMS) (Jackson et al., 2013). Two types of temperatures were measured by the SIMBA. The temperature of air, snow, ice, and water where SIMBA thermistor sensors were placed, is named as SIMBA_ET. The temperature reading after each thermistor sensor was applied with an identical amount of heat, is named SIMBA_HT. The amount of heat was controlled by the duration of heating, often configured as the 30s and 120s, respectively. The SIMBA_ET and SIMBA_HT were measured four times per day and one time per day, respectively. So SIMBA_HT(30) and SIMBA_HT(120) represent the sensor temperature changes in air, snow, ice, and water after a heating cycle of the 30s and 120s, respectively. The length of the SIMBA thermistor chain is 4.8m. There are 240 thermistor sensors (DS28EA00, accurate to +/- 0.0625°C) with 0.02 m spacing. Combined with a SIMBA algorithm (Cheng et al., 2020) and manual analyses, snow depth and ice thickness can be derived from SIMBA_ET and SMMBA_HT observations. Overall, the measurement accuracy was 0.02 m for both the snow depth and ice thickness. The submitted data package includes 6 data files, i.e., SIMBA GPS position; snow depth; ice thickness; SIMBA_ET, as well as in situ snow depth and ice thickness measured by the local personnel.

The SIMBA (IMEI: 300234068703800) was deployed on land-fast ice on 29 October 2020. The air temperature was -10 °C at the time when SIMBA was deployed. The first thermistor sensor (No. 1) was placed in the air and the last thermistor sensor (No. 240) was placed in the ocean. The initial ice thickness was 29 cm; The surface snow was 0.5 – 1 cm. Sensor No. 50 was located at the sea ice surface. Sensor No. 65 was at the ice bottom.The measurement was done at a fixed location (20.24924W,74.314426N); The elevation was sea level;The SIMBA measurement started on 29 ‎October ‎2020 and ended on 10-Apr-2021. The first in situ snow depth and ice thickness were measured on 28 October 2020; The last in situ snow depth and ice thickness were measured on 17 May 2021.