Experimental evidence of the strong connection between the near-noon level of ionization in the high-latitude ionosphere, expressed as the f0F2 values, and the subsolar distance between the magnetopause and the Earth is presented here. Preliminary studies made by the authors of the solar wind dynamic pressure influence on the high-latitude ionosphere produced rather promising results. Since the solar wind dynamic pressure is an external force determining a subsolar distance between the magnetopause and the Earth, the former parameter was chosen as an indicator of the electromagnetic energy accumulated in the magnetosphere-ionosphere system. Very high correlation (r>0.85) has been found between the values of the near-noon electron density derived from the data of the high-latitude ionospheric stations located in different geophysical regions of both hemispheres and the magnetopause position. The periods when the magnetopause moved close to the Earth coincided with the dramatic drop of the near-noon ionization level at the high-latitude stations. However, only preliminary suggestions concerning the nature of this phenomenon can be made at the moment. ¿ 1998 American Geophysical Union