During the Arctic Ocean Expedition 1996 we measured radiative, turbulent, and conductive heat fluxes from late summer to early freeze-up, over the Norwegian Sea into the Arctic Ocean to latitude 88°N, mainly in air that had spent several days over the pack ice. In summer the net radiation was positive, on average +26 Wm-2, where the leads contributed more than the ice floes. Clouds had a cooling net effect. During the freeze-up period the net radiation was dominated by the ice floes, on average -8 Wm-2, with a warming cloud net effect. The turbulent fluxes were on average small and unable to balance the net radiation, except during cyclone activity, when the total turbulent heat fluxes averaged to +11 Wm-2. During the freeze-up period the conductive heat flux averaged to -4 Wm-2. In summer, melting of ice must largely have caused the average positive residual (+21+/-5Wm-2). During the freeze-up period the average negative residual (-7+/-3Wm-2) must result from formation of new ice and oceanic turbulent/convective fluxes in the leads. There was a diurnal cycle in net radiation both in summer (17 Wm-2 average amplitude) and the freeze-up period (8 Wm-2). The turbulent sensible heat flux (average amplitude ~5 Wm-2), as well as the turbulent latent heat flux (1 Wm-2 in summer) and conductive flux in the ice (2.5 Wm-2 during the freeze-up) responded to this. These results emphasize the high sensitivity of the heat and radiation budget balances to changes in cyclone activity, leads, and clouds.