Ocean microstructure profiles were obtained from a MSS (Microstructure Sensor Profiler, Sea&Sun Technology, Germany) profiler between 13 July and 6 August 2022 during the RV Polarstern PS131 cruise, ATWAICE, from ice floes as well as at stations from the ship. The aim of this expedition was to investigate sea ice summer melt processes, with a focus on the contribution of the Atlantic water inflow into the region. In total, 183 files of single casts are submitted, of which 19 were collected from ship and 164 from ice. Please see the detailed log spreadsheet for stations and comments. Throughout the cruise, the instrument functioned well, except the vibration sensor did not work and the fast thermistor channel produced a cut-off at low end, probably for output that exceeded the range of the A/D converter of the probe. In the later part of the cruise episodic data transmission errors were encountered. The dissipation rate was measured using two airfoil shear probes. The dataset has been processed and formatted in accordance with the SCOR Working Group ATOMIX guidelines and recommendations (Lueck et al., 2024; https://doi.org/10.3389/fmars.2024.1334327). One NetCDF (NC) file per instrument's native file is provided. Each provided NC file is organized in five hierarchical groups including continuous time series of data converted into physical units, cleaned time series used for spectral analysis, wavenumber spectra, dissipation rate estimates, and 0.1 dbar vertically averaged profiles from the precision conductivity, temperature and auxiliary sensors. The temperature and the practical salinity obtained from the MSS are corrected against the shipboard SBE-911plus CTD system (calibrated against salinity water samples). The grouped NC files are large and may be impractical to download and merge. For users only interested in the dissipation estimates and other time-averaged profiles, we also provide two separate NC files with all dissipation rate (and other related parameters) profiles and 0.1-dbar vertically averaged sensor data, collated into one file each. The collated files are, additionally, manually quality controlled and cleaned, whereas the per-file NC files are screened using automated routines. For more detailed information, please refer to the comments within the data file. The raw (binary, native format), full-resolution data from the microstructure profiler are available from Fer et al. (2023), https://doi.org/10.1594/PANGAEA.956086. The observations on ice floes are complemented by simultaneous ocean current measurements from an ice-mounted Acoustic Doppler Current Profiler, see https://doi.org/10.1594/PANGAEA.978165.

The data are organized as follows. The table MSS_log_with_events.xlsx contains a list of all casts with additional metadata from the deployments. For each listed cast, we provide a single netCDF file. The file names correspond to the cast number in the log table, and are also identical to the corresponding raw data, which are too published in PANGAEA. The single-cast netCDF files contain detailed metadata, an example is provided as the text file ncdump_CAST0199.txt.For most users it might be more convenient to work with merged data files. The files MERGED_EPSI.nc and MERGED_CTD.nc are constructed by concatenating time series from the individual NC files. Data in the collated files are not gridded in time or pressure. Each data point has its own time stamp and pressure value, with time increasing monotonically from the start of the first section. When producing the merged files, we performed additional quality screening, updated the flag values, and used only good data (i.e., quality flags are applied). More details can be found in the description and attributes of the two merged NC files. We also provided text files with the metadata from these files (ncdump_MERGED_EPSI.txt and ncdump_MERGED_CTD.txt).The authors are grateful to the captain, crew, and technical/scientific staff of the expedition PS131 onboard RV Polarstern.