The structure and dynamics of polar mesosphere summer echoes observed with the EISCAT 224 MHz radar

Abstract

The EISCAT 224 MHz radar was operated in a high spectral resolution mode to study polar mesosphere summer echoes. Intermittent and localized scattering regions of less than 1 km thickness were observed. Gravity waves were present, which were occasionally steepened. Turbulent velocity fluctuations were not obviously related to certain phases of the observed short‐period gravity waves. We explain the large signal amplitudes of these polar mesosphere summer echoes to result from backscatter due to electron density variations, which extend to scales shorter than the scales of neutral turbulence.