A new 30 MHz radar system, Gadanki Ionospheric Radar Interfereometer (GIRI), has been established at NARL by ISRO for ionospheric, meteor and space weather research. GIRI consists of a rectangular antenna array of 160 two-element Yagi-antenna arranged in a 20x8 matrix, twenty transmitter units providing a maximum peak power of 160 kW, six digital receivers including data processing systems, a radar controller, and a host computer.National Atmospheric Research Laboratory (NARL) at Gadanki, an autonomous research institute of Department of Space, is engaged in fundamental and applied research in the field of Atmospheric Sciences located at Tirupati in Andhra Pradesh.
GIRI has been designed with the following objectives:
- to carry out unattended observations towards studying the forcing from the sun (e.g., variation in solar flux, solar flare, magnetic storm) and from the underneath atmosphere (e.g., waves generated by weather phenomena) on the ionospheric irregularities
- to steer the radar beam on a pulse-to-pulse basis up to ±50o in the east-west plane providing spatial map of ionospheric irregularities covering about 10o longitude belt around Gadanki, to study evolution of irregularities
- to measure Doppler velocity unambiguously by taking advantage of the wavelength (10 m) and also by double-pulse technique to study polarisation processes and supersonic plasma flow
- to measure Doppler spectrum of overspread targets with a-periodic pulsing scheme to study different regimes of electrostatic turbulence
- to measure zonal drift of irregularities using interferometry technique
- to perform in-beam interferometric imaging of small scale structures and their dynamics.
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