Vertical profiles of water temperature, salinity, dissolved oxygen and chlorophyll were measured by the Drift Towing Ocean Profiler (DTOP) buoy 2018, an autonomous platform, installed on drifting sea ice (ice thickness: 155cm; snow depth: 5cm; freeboard: 10cm) in the Arctic Ocean during Chinese Arctic Research Expedition 2018. The resulting time series describes the vertical profile of the ocean below the sea ice as a function of place and time between 22 August 2018 and 24 December 2018 in sample intervals of 12 hours. In addition, the DTOP measured air temperature, relative humidity and barometric pressure and GPS position at hourly intervals.

The data set has been processed and contains quality flags for different kinds for erroneous data. Flag values are the sum of individual error codes. The value of 0 refers to no error.Quality flag, position: The geographic position is flagged +1 if the drift velocity, as derived from the GPS longitude and latitude, exceeds a threshold of 10 deg latitude or 50 deg longitude per time step; +2 if the position exceeds extreme values, such as longitude > 360 deg; +4 if the position is exactly 0.0.