EAGER: Adapting the New Arecibo On-Dish High Frequency (HF) Transmitter System to Radar Mode

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The investigators will develop a radar capability for the new Arecibo high frequency (HF) ionospheric heating facility using off-dish interferometric receive techniques. They will also explore using an on-dish receive mode that would require a T/R (transmit/receive) switch. The off-dish interferometric receiver systems would employ small arrays of active antennas and, after the initial analog filtering, a fully digital receiver system. Both the on and off-dish receiver systems could be used simultaneously yielding the most sensitive system. This radar system will enable new science by adding capabilities to conduct studies of meteor physics. Recent discoveries have shown that the vast majority of meteoroids visible as radar meteors fragment rather than simply ablating. This process is a likely source of important nanometer ?dust? in the 80-130 km altitude region where meteors ablate. The radar would be used in conjunction with the 46.8 MHz and 430 MHz radars at Arecibo to explore fragmentation. The combined measurements would allow studies of the radiowave scattering mechanism in meteor trails, and the processes whereby meteors deposit important metals in the atmosphere. Other important science areas include studies of mid-latitude spread-F, sporadic-E instabilities, quasi-periodic echo (QPE) structures, low-altitude quasi-periodic echoes (LQPE) structures, and the D-region ionization enhancements associated with lightning. The instrument could also find application as an MST (Mesospheric-Stratospheric-Tropospheric) radar and as a potential transit solar corona radar at solar minimum. Extending the HF heater capabilities to include a radar mode will enable much new science from the Arecibo instrument cluster. The HF-radar will allow direct probing of D-region heating effects, and possibly detection of lightning-induced D-region ionization. The effort will provide new opportunities for student research involvement by further enabling common-mode multi-radar campaigns and by supporting on-going model development efforts. Undergraduate students will be involved in building and fielding the system that will be available to all user communities, including students from collaborating institutions.