During the Polarstern cruise PS131 infrared (IR) brightness temperatures of the surface (open ocean and sea ice) were recorded from onboard the vessel with a down-looking infrared camera (Infrared VarioCAM HDx head camera from InfraTec) that was installed on starboard on the upper deck (at around 21.5 m from sea level ('Peildeck')). The viewing angle (off-nadir) was around 70° and the camera has a field of view of 57.1° × 44.4°. Each image has a size of 640 × 480 IR pixels. The images are stored as netCDF files where one file includes data from one day. For each image, latitude and longitude information are included. They are obtained from the mastertrack of the ship (doi:10.1594/PANGAEA.950999). In addition the dataset contains the viewing angle for each image obtained from an auxiliary inertial measurement unit (IMU) installed on the IR camera that was resampled to 2 seconds. Missing data of the IMU was filled by the average of the existing angle measurements of the respective day or, if that was not available, by a fill-value of 70°.The IR camera was operated in conjunction with a visual camera, pointing at the same target.The IR camera data was recording one image every 10 minutes from 3 July - 10 July. From 10 July, 16:00 UTC, the cameras was operated with a sampling rate of 0.2 Hz, taking a picture every 5 s. Data is missing on 24 July from 7:09-19:22 and on 7 August from 17:16-21:20 when the recording was stopped. The images contain open ocean as well as sea ice in the eastern Fram Strait, the marginal ice zone in Fram Strait, during the transit to the Aurora vent field (high ice concentration) and near East Greenland (fast ice).

The data files are netCDF files (one per day) with a time coordinate. The brightness temperature (IR) images (variable called temps) have the spatial dimensions of 480x640. In addition, the variables latitude, longitude and viewing_angle are included.