In the framework of the Multidisciplinary Observatory for the Study of Arctic Climate (MOSAiC) expedition, the tethered balloon system BELUGA (Balloon-bornE moduLar Utility for profilinG the lower Atmosphere) was deployed from a research camp on an ice floe drifting in the Fram Strait in Summer 2020. The BELUGA system consists of a 90 m³ helium-filled balloon with modular instrumentation. Lonardi et al. 2021 (submitted to Elementa) gives an overview of the BELUGA observations during MOSAiC leg 4. Pilz et al. (in preparation) describe the BELUGA operations and data processing routines. The present data set covers the aerosol particle measurements with the Cubic Aerosol Measurement Platform (CAMP) (details in Pilz et al. in preparation) on 18 flights with mean altitudes of 1 km between 29 June and 27 July 2020.