Abstract
We report new results from the 50-MHz Jicamarca radar in Peru (12°S, 77°W), which is able to observe backscatter from the daytime mesosphere on any given day. Since 2005, the radar has been operated in a high-power MST-ISR mode for 3-day runs four times per year to study the seasonal variation of mesospheric echoes. Doppler spectra are obtained with 1 min and 150-m nominal resolution yielding power, horizontal and vertical winds, and spectral width. The rich echo structures contain braids and billows suggestive of Kelvin-Helmholtz instability (KHI). We present three cases; (1) a short sequence of billows growing in height and becoming unstable; (2) a long train of billows showing high levels of turbulence at two different locations; and (3) a series of billows passing only slowly through the field of view. In all cases, the layers were associated with strong wind shears, mature billows were 1-1.5 km tall, and separation of KH phase fronts was 8-10 km. We compare our observations with OH imager observation and numerical simulations.
Original language | English (US) |
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Pages (from-to) | 734-743 |
Number of pages | 10 |
Journal | Advances in Space Research |
Volume | 40 |
Issue number | 6 |
DOIs | |
State | Published - 2007 |
Keywords
- Equatorial mesosphere
- Kelvin-Helmholtz instability
- Turbulence
- VHF echoes
- VHF radar
ASJC Scopus subject areas
- Aerospace Engineering
- Astronomy and Astrophysics
- Geophysics
- Atmospheric Science
- Space and Planetary Science
- General Earth and Planetary Sciences