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Ann. Geophys., 24, 1281-1293, 2006
www.ann-geophys.net/24/1281/2006/
© European Geosciences Union 2006
A high-resolution study of mesospheric fine structure with the Jicamarca MST radar
R. Sheth1,*, E. Kudeki1, G. Lehmacher2, M. Sarango3, R. Woodman3, J. Chau3, L. Guo2, and P. Reyes3
1University of Illinois at Urbana-Champaign, IL 61801, USA
2Clemson University, Clemson, SC 29634, USA
3Jicamarca Radio Observatory, Lima 13, Peru
*now at: Lincoln Laboratories, Lexington, MA 02420, USA
Abstract. Correlation studies performed on data from recent mesospheric experiments
conducted with the 50-MHz Jicamarca radar in May 2003 and July 2004
are reported. The study is based on signals detected from a combination
of vertical and off-vertical beams. The nominal height resolution
was 150 m and spectral estimates were obtained after ~1 min integration. Spectral widths and backscattered power generally
show positive correlations at upper mesospheric heights in agreement
with earlier findings (e.g., Fukao et al., 1980) that upper mesospheric
echoes are dominated by isotropic Bragg scatter. In many instances
in the upper mesosphere, a weakening of positive correlation away
from layer centers (towards top and bottom boundaries) was observed
with the aid of improved height resolution. This finding supports
the idea that layer edges are dominated by anisotropic turbulence. The data
also suggests that negative correlations observed at lower mesospheric
heights are caused by scattering from anisotropic structures rather
than reflections from sharp vertical gradients in electron density.
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