Temperature and heating-induced temperature differences were measured along a chain of thermistors. SIMBA 2020T61 (a.k.a. UiT0206) is an autonomous instrument that was installed on drifting sea ice in the Arctic Ocean during MOSAiC (Leg 2) in February 2020. The thermistor chain was 5 m long with 250 evenly distributed temperature sensors.The resulting time series describes the evolution of temperature and temperature differences after two heating cycles of 30 and 120 s as a function of location (GPS), depth and time between February 5th, 2020 and July 27th 2020 at 6 hour intervals for temperature and 24 hours for temperature differences. The buoy was installed on the transect across “Alli's Ridge” on the first year ice (FYI) flank of the ridge, away of the second year ice (SYI) floe of the Central Observatory.In addition to temperature, geographic position (GPS), barometric pressure, air temperature measured 1m over the ice level, tilt and compass were measured.This instrument was deployed as part of the project "Ridges - Safe HAVens for ice-associated Flora and Fauna in a Seasonally ice-covered Arctic OCean" (HAVOC), funded by the Research Council of Norway, project number: 280292, "Coordinated Arctic Acoustic Thermometry Experiment" (CAATEX), funded by Norwegian Research Council, project number: 280531 and "Arctic Ocean ecosystems - Applied technology, Biological interactions and Consequences in an era of abrupt climate change" (Arctic ABC Development, Research Council of Norway, project number: 245923).