A comprehensive one-dimensional model of the polar ionosphere has been used in conjunction with incoherent-scatter radar data from Sondrestrom, Greenland, to determine downward heat fluxes and thermal ion outflows at very high latitudes. For periods of very quiet geomagnetic activity the model closely simulates the observed time-dependent behavior of the electron density, ion and electron temperatures. To obtain this similarity between model and data, the upper boundary conditions of the model, namely downward heat flux, and magnetic field-aligned ion flows, are continually adjusted with time to provide a best fit with data. The heat fluxes and ion flows are determined indirectly from this fitting procedure. The technique has been applied to a 10-hour daytime data set for February 12, 1990, to search for enhanced downward heat fluxes and outward thermal ion fluxes associated with dayside auroral oval. Variations of heat flux ranged from about 2¿109 to 2¿1010 eV cm-2 s-1, and vertical outward fluxes of ionization ranged from about zero to 8¿108 cm-2 s-1. For both quantities the peak values occurred when the radar site was located under the dayside auroral oval. It is suggested that these marked upward thermal ion flows in the dayside auroral ionosphere may be associated with energetic O+ ion outflows that have been observed at high altitudes with spacecraft. ¿ American Geophysical Union 1995