This data contains sea ice emissivity observations from the Microwave Radar/radiometer for Arctic Clouds (MiRAC; Mech et al., 2019) onboard the Polar 5 aircraft during the ACLOUD (RF23 and RF25) and AFLUX (RF08, RF14, and RF15) field campaigns. MiRAC consists of two components: MiRAC-A with an 89 GHz channel (25° incidence angle, horizontal polarization) and MiRAC-P with six channels around the 183.31 GHz water vapor absorption line (183.31±0.6, ±1.5, ±2.5, ±3.5, ±5.0, and ±7.5 GHz) and two window channels at 243 and 340 GHz (nadir). Note that the polarization and viewing angles of MiRAC-A and -P differ. The emissivity was calculated from the observed brightness temperature with ancillary information on the surface temperature from a KT-19 infrared radiometer and atmospheric profile. The radiative transfer simulations required for the emissivity calculation are performed with the Passive and Active Microwave radiative TRAnsfer (PAMTRA) model (Mech et al., 2020). Further details on the emissivity calculation are described in Risse et al. (2024).