During a voyage to the north pole from Alaska by the icebreakers USCGC Polar Sea and Canadian CGC Louis S. St-Laurent (the 1994 Arctic Ocean Section, July 24 to September 3) an atmospheric radiation and remote sensing experiment measured downwelling shortwave and longwave radiation reaching the sea ice surface. The experiment included a Fourier transform infrared (FTIR) spectroradiometer which measured zenith radiance at 1 cm-1 resolution in the middle infrared wavelength range 5--20 μm, an Eppley pyranometer measuring most of the downwelling shortwave flux (0.28--2.80 μm), an Eppley pyranometer measuring the downwelling near-infrared flux (0.78--2.80 μm), and an Eppley pyrgeometer measuring the downwelling longwave flux. In conjunction with a discrete-ordinates radiative transfer model, the FTIR emission spectra are used to estimate 8--12 μm cloud emissivity and effective radius of the cloud droplet size distribution. The broadband shortwave flux measurements are used to estimate shortwave cloud scattering optical depth. Most of the FTIR emission spectra recorded under overcast skies are consistent with cloud effective radius in the range 10--12 μm, but 27% of the spectra are more consistent with the range 4--6 μm, suggesting an occasional continental aerosol influence to Arctic cloud microphysics. The average daily shortwave cloud-scattering optical depth ranged from 2 to 46, which is similar to a range inferred from radiometer data recorded at Barrow, Alaska, during the same season. The downwelling shortwave flux measurements and estimates of net surface flux are generally consistent with a four-decade Russian climatology but also suggest that the frequency of cloud cover sampled during the 1994 Arctic Ocean Section was somewhat larger than the climatological average. These radiation measurement data from the 1994 Arctic Ocean Section should be useful for examining the treatment of atmospheric radiation and surface energy input in Arctic climate model simulations.¿ 1997 American Geophysical Union