The University of Bath's Ascension Island meteor radar (7.9 S, 14.4 W) is an all-sky VHF meteor radar commercially produced Skiymet system. The system was operational from October 2001 to June 2011, albeit with some gaps in the data coverage. In normal operation, the radar was operated continually.
The Skiymet radar system has the following parameters:
- Radio frequency 43.5 MHz
- Pulse repetition frequency 2144 Hz
- Transmitter peak power 12 kW (sometimes 6 kW)
- Duty cycle 15%
The radar detects radio scatter from the ionised trails of individual meteors drifting with the winds of the upper mesosphere, mesopause and lower thermosphere. A low-gain transmitter antenna is used to provide broad illumination of the sky. An array of five receiver antennas act as an interferometer to determine the azimuth and zenith angles of individual meteor echoes. Doppler measurements from each meteor determine the radial drift velocity and the meteor is assumed to be a passive tracer of atmospheric flow. The radar typically detects of order a few thousand meteors per day. These observations can be used to determine zonal and meriodional winds in the mesosphere, mesopause and lower thermosphere at heights of about 80 – 100 km and with height and time resolutions of ~ 3 km and 2 hours.
The radar produces daily “meteor position data” data files (mpd files) recording the details of each individual meteor echo. In normal operation a few thousand individual meteors are detected per day. The key data parameters recorded for each meteor echo include:
1. Date and time of the meteor detection
2. Range to the meteor echo point
3. Height of the meteor echo above the ground
4. Radial drift velocity of the meteor echo and its uncertainty
5. Zenith and azimuth angles of the meteor echo
6. Ambiguity levels in the determined zenith and azimuth angles
7. Decay time of the meteor echo
8. Meteor echo power and S/N ratio
Recordings are made for each individual meteor detected allowing measurements of zonal and meriodional wind speeds in the mesosphere and lower thermosphere to be obtained. Meteor count rates vary diurnally and with season, but are usually up to a few thousand meteors per day.
A description of the Skiymet meteor radar can be found in W.K. Hocking et al. (2001). See related documentation on this record.
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