Turbulence scattering layers in the middle-mesosphere observed by the EISCAT 224-MHz radar
Article first published online: 7 DEC 2012
Copyright 1992 by the American Geophysical Union.
Volume 27, Issue 2, pages 97–107, March-April 1992
How to Cite
1992), Turbulence scattering layers in the middle-mesosphere observed by the EISCAT 224-MHz radar, Radio Sci., 27(2), 97–107, doi:10.1029/91RS02963., , , and (
- Issue published online: 7 DEC 2012
- Article first published online: 7 DEC 2012
- Manuscript Accepted: 6 NOV 1991
- Manuscript Received: 18 DEC 1990
Spectral measurements of signals scattered from altitudes well below 70 km have for the first time been obtained with the EISCAT 224-MHz radar. Observations with the antenna pointing away from the vertical at times show spectral power distributions departing markedly from those expected from collision-dominated incoherent scatter theory. Separated peaks in the spectra occur in regions of abrupt shear in the velocity of the neutral wind within the scattering volume. Anomalously large backscattered power levels are sometimes observed in the vicinity of such shears at altitudes near 68 km. It is unlikely that these echoes are due to incoherent (Thomson) scatter. Instead, it is proposed that the abrupt velocity shears develop neutral turbulence in narrow layers and that these layers cause the enhanced backscatter. Calculations of the expected backscatter power levels at 224 MHz for incoherent scatter and for turbulence scatter show that the turbulence component can be the dominant one at heights below about 68 km if the potential refractive index gradient and the turbulence energy dissipation rates are large enough.