The investigators will use the enhanced instrument cluster at Arecibo Observatory (AO) to gain new insight into the complex nature of the space-atmosphere interaction region (SAIR). The new High Frequency (HF) heating facility with the ISR (Incoherent Scatter Radar) and other instruments provides a unique opportunity to study heating-related aeronomic and plasma physics problems. This includes the rapidly-imaged observation of airglow at 557.7 nm, 630.0 nm and 427.8 nm during ionospheric "heating" campaigns to understand the role of HF-heating in generating plasma bubbles, or modulating them if already present, and to understand the role of secondary suprathermal electrons in producing airglow at different wavelengths. This research will also yield insight to the heating process, including locating ionospheric "hot-spots", yielding details of the electron collision process, elucidating the role of Langmuir and ion-acoustic waves in the strongly heated regions, and study of heating effects in Sporadic E. The latter study will include Ca+ metal-lidar observations as further defined by 555.7 nm imaging as well as ISR and HF radar results. HF heating of the ionosphere offers a unique opportunity to investigate the plasma heating process and its effects on the neutrals in a controlled (experimental) fashion. Outside of the heating campaigns, a database of 630 nm all-sky camera images from other locations will be assembled collaboratively to investigate the global context of the omnipresent ~1 hr period ionospheric waves, and associated dynamics, first identified with the AO ISR. This work will utilize other AO instruments, including the resonance and Rayleigh lidars, to investigate the role of wave coupling from lower atmospheric regions. Also, a proposed new CCD camera will allow high speed imaging to better understand HF heating effects and linking optical and radar meteors to study meteoroid aeronomy. The response of the SAIR to sudden changes in the environment caused by heating will be explored with the collaborative use of multiple instruments, thus informing numerous geophysical research areas. The multidisciplinary nature of this work will help to establish collaborations with plasma physicists, modelers, and space weather scientists. It will also advance the AO cluster capabilities with the addition of a User-Owned, Public Access (UOPA) high frame rate CCD to the current imager and help in establishing international collaborations. Students representing minorities from local universities in Puerto Rico will be encouraged to participate in observations and data analysis. They will be involved in the improvements of the optical systems including training on AO instrumentation and the application of these instruments to study aeronomy of the SAIR.
