10/23/2026
By Lynne Schaufenbil

Please join the Lowell Center for Space Science and Technology (LoCSST) for a talk by Dr. Sevag Derghazarian.

  • Date: Friday, Oct. 30
  • Time: 2 p.m.

Topic 1: Mid-Latitude Ionospheric Variations Above the Eastern U.S. During the April 2024 Solar Eclipse Using Millstone Hill ISR

This portion of the talk will focus on the regional ionospheric parameter changes associated with the April 8, 2024, solar eclipse in the eastern to central United States, using 6° elevation, wide-sweep azimuth scans from the Magnetosphere-Ionosphere Steerable Antenna (MISA) of the Millstone Hill Incoherent Scatter Radar. The radar's field of view covers a large portion of the continental U.S. (25–55° N, 75–95° W) and is capable of observing altitude profiles from the E-region up to the topside ionosphere. To the best of our knowledge, this is the first study that presents simultaneous observations of the altitude-resolved response of Ne, Te and Ti to a solar eclipse over a broad geographic area, and uses a polynomial regression model to predict the background ionosphere. Significant spatial and temporal differences were found in each parameter's response to the eclipse and will be presented. Some of the key features are maximum electron density (Ne) drops of up to 50% in the F1 region, an electron temperature decrease on the order of 40% (850 K) that closely mirrors the obscuration percentage, and an ion temperature (Ti) decrease of up to 20%, or 225 K, in a narrow geographic area and at two distinct altitude regions.

Topic 2: Investigating Ionospheric Signatures and Precursors of STEVE Using PFISR Data and GNSS Scintillation Signatures

Strong Thermal Emission Velocity Enhancement (STEVE) events are bright, mauve optical emissions that periodically occur around magnetic midnight in subauroral regions, often after a substorm onset. Substorms are known to generate STEVE events, but the vast majority of substorms are not associated with STEVE emissions. In addition, STEVE is associated with high-velocity subauroral ion drift (SAID) flow, but it is still a mystery which specific characteristics of SAID channels lead to visible STEVE emissions. A novel and compelling component of this research is the incorporation of multi-instrument data and analysis from 2010 to 2025: Poker Flat Incoherent Scatter Radar (PFISR) plasma parameter and ion drift velocity data, THEMIS all-sky imager data, SuperDARN ion velocity data, and CHAIN GNSS data.

Bio

Sevag Derghazarian completed his Ph.D. at Cornell University in the Department of Electrical and Computer Engineering, with a focus on upper atmospheric physics, and subsequently pursued his postdoctoral work at MIT Haystack in the Geospace group. Sevag’s research expertise and interests include high-altitude irregularities of the equatorial topside ionosphere (high-altitude echoes), topside ionospheric measurement at extremely low solar flux, traveling ionospheric disturbances (TIDs) and gravity waves (GWs) connections using GNSS and in situ datasets, and solar eclipse-induced changes in the eastern U.S. using data from the Millstone Hill Steerable Antenna (MISA). He recently moved to the Center for Solar-Terrestrial Research at New Jersey Institute of Technology, where he is pursuing research on STEVE (Strong Thermal Emission Velocity Enhancement) using various ground-based and in situ datasets.

If you are interested in attending, please email Lynne_Schaufenbil@uml.edu.