Thermal infrared imaging was performed with a down-looking thermal infrared camera (7.5–14 µm) installed in a helicopter. The instrument used was the Infrared VarioCAM HD head 680 camera from InfraTec. This data set includes raw data from multiple flights, which were performed, from a local (~5 km) up to a regional scale (~50 km) from October 2019 to May 2020 and again in September 2020 as part of the MOSAiC expedition in the Arctic Ocean. The common flight duration was about 90 minutes at an altitude of about 300 m. This raw data comes in the proprietary IRB format to open with the IRBIS 3.1 software from the InfraTec company. Each file includes one minute of recording at 4Hz frequency. A processed subset of the data is available under doi:10.1594/PANGAEA.941017. During the same helicopter flights an airborne laser scanner (ALS), optical cameras, and radiation sensors were operated (hdl:10013/sensor.50176d2b-6378-4b9f-98f3-2a09e940f572).

IRB is a proprietary data format for recording thermographic data, i.e. spatial images of temperatures. It can be opened by software "IRBIS" by InfraTec (www.infratec.eu).