Physics Dept Seminar

November 21, Friday (*SPECIAL DAY*)

Radar studies of ionospheric irregularities with AMISR-14: New two-dimensional observations

Alexander A. Massoud

U. of Texas - Dallas

(Terrestrial Physics, Host: Goodwin)

Room: ECE 202

Time: 11:45 am - 12:45 pm with 11:30 am teatime

Equatorial spread F (ESF) is the general term that refers to signatures of ionospheric F-region irregularities observed with different instruments. The generation of ESF is often attributed to the pre-reversal enhancement of the equatorial F-region vertical drifts at sunset. However, recent studies have pointed out difficulties in the interpretation of traditional (i.e., single beam) radar observations of ESF. Here, we emphasize the difficulty of determining where/when ESF developed. The question of ESF origin may be even more relevant when F-region irregularities are measured during local times or seasons when the conditions to stimulate their development are not expected to be present overhead. Advances in our understanding of atypical ESF require advances in observational capabilities. To contribute toward these efforts, we have analyzed results from new two-dimensional (2D) observations of F-region echoes. The observations have been obtained using AMISR-14, a 14-panel version of the Advanced Modular Incoherent Scatter Radar system, which is located at the Jicamarca Radio Observatory in Perú. We primarily highlight the capability of AMISR-14 to “scan” the magnetic equatorial plane and produce measurements of ESF across ~400 km centered at Jicamarca. The measurements allow us to determine, unambiguously, whether ESF was generated within the instrument field of view (i.e., local) or entered from outside it (i.e., non-local). This talk will address new studies of ESF using AMISR-14 observations made semi-routinely since July 2021. We present results in an effort to demonstrate our ability to address the following science questions:

1. What is the climatology of sub-meter F-region irregularities as observed by AMISR-14? To what extent does this behavior follow the behavior of F-region echoes produced by meter-scale irregularities?

2. How often are radar echoes associated with post-midnight irregularity structures measured above Jicamarca generated within a few 100s of km of the facility?

3. Under what vertical plasma drift conditions are these local post-midnight echoes first measured?