More than 600 weather balloon flights were conducted with GPS RAWINSONDES as part of the SHEBA Experiment between October, 1997 and July, 1998. The measurements sample the atmospheric environment over a mix of multiyear and first year pack ice, drifting in the Arctic Ocean between the 74th and 79th parallels. The measurements resolve variations in the vertical profiles of air temperature, relative humidity, and horizontal wind velocity from the surface to the tropopause, with typical vertical resolution of 10-50 meters and typical temporal resolution of 6-12 hours. Using orthogonal functions to represent the variability, the contributions of the interseasonal and higher frequency variability are studied. The profile thermodynamic data are analyzed with simultaneous observations of wind velocity, cloud cover and broadband incident irradiance at the surface, to assess relationships with the surface heat balance and horizontal temperature advection. Surface and top-of-the-atmosphere shortwave and longwave irradiance are simulated with a radiative transfer model using the profile thermodynamic data as input, for comparison with irradiance measurements. Synoptic time scale variations in the cloud cover and temperature advection dominate the higher frequency variations in surface net and longwave irradiance during winter. During summer the relationships are more complicated, depending on the shortwave and longwave incident irradiance as well as the surface albedo.