Mid-Latitude Ionospheric and Thermospheric Eclipse Responses in Solar Minimum Conditions, and Plans for 2024 Observations at Millstone Hill
Abstract
Eclipses feature large reductions in EUV irradiation of Earth's atmosphere and cause dramatic effects on ionospheric and thermospheric dynamics. Even well away from the direct totality region, the passage of the penumbral shadow through the mid-latitude and subauroral ionosphere is a potent driver of large temperature, density, and transport changes as well as wave activity. In preparation for future eclipse events, we will review results of several recent studies on solar eclipse observations at mid-latitudes, including those from the large North American eclipse in August 2017. During this event, the mid-latitude Millstone Hill incoherent scatter radar measured full profiles of ionospheric plasma dynamics and thermal state. Vertical response features included a 30-40 percent decrease in electron density, a 100 to 220 K decrease in electron temperature, and a 50 to 140 K decrease in ion temperature near Millstone Hill more than 1000 km away from totality. Several unexpected features occurred in this event, including a maximum electron density decrease above 200 km and atypical post-sunset upward vertical drifts. We will review these findings and compare them to our increased understanding of response mechanisms based on modeling of eclipse effects at these latitudes. We will also discuss evolution of ionospheric response with latitude and time based on radar observations, augmented with global GNSS total electron content (TEC) observations. Finally, we will describe comprehensive planning at the Millstone Hill Geospace Facility for multi-faceted observations during the upcoming April 2024 total eclipse . In particular, this event will have a totality track on the eastern US coast that is readily within the wide field scanning capability of Millstone Hill's UHF incoherent scatter radar. Furthermore, to increase coverage, numerous high-rate (>= 1 Hz) GNSS receivers will be deployed along the path of totality to provide observations in addition to standard and specialized high-rate TEC products available from the Millstone Hill Geospace Facility.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMSY0140001E
- Keywords:
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- 0815 Informal education;
- EDUCATION;
- 2437 Ionospheric dynamics;
- IONOSPHERE;
- 6934 Ionospheric propagation;
- RADIO SCIENCE;
- 6964 Radio wave propagation;
- RADIO SCIENCE