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Full-Text Articles in Physical Sciences and Mathematics
Modification Of The Lower Ionospheric Conductivity By Thunderstorm Electrostatic Fields, Mohammad A. Salem, Ningyu Liu, Hamid K. Rassoul
Modification Of The Lower Ionospheric Conductivity By Thunderstorm Electrostatic Fields, Mohammad A. Salem, Ningyu Liu, Hamid K. Rassoul
Aerospace, Physics, and Space Science Faculty Publications
This paper reports a modeling study of the modifications of the nighttime lower ionospheric conductivity by electrostatic fields produced by underlying thunderstorms. The model used combines Ohm's law with a simplified lower ionospheric ion chemistry model to self-consistently calculate the steady state nighttime conductivity above a thunderstorm. The results indicate that although the electron density is generally increased, the lower ionospheric conductivity can be reduced by up to 1-2 orders of magnitude because electron mobility is significantly reduced due to the electron heating effect. For a typical ionospheric density profile, the resulting changes in the reflection heights of extremely low …
Ground Detection Of Terrestrial Gamma Ray Flashes From Distant Radio Signals, Fanchao Lyu, Eric Cramer
Ground Detection Of Terrestrial Gamma Ray Flashes From Distant Radio Signals, Fanchao Lyu, Eric Cramer
Aerospace, Physics, and Space Science Faculty Publications
Terrestrial gamma ray flashes (TGFs) are brief bursts of energetic gammy-ray photons generated during thunderstorms, which have been detected almost exclusively by satellite-based instruments. Here we present three lines of evidence which includes the three out of three simultaneously observed pairs, the same occurrence contexts, and the consistent estimated occurrence rate, which indicate a direct relationship between a subset of TGFs and a class of energetic radio signal easily detectable by ground-based sensors. This connection indicates that these gamma ray and radio emissions are two views of the same phenomenon and further enable detection of these TGFs from ground distant …
Observation-Constrained Modeling Of The Ionospheric Impact Of Negative Sprites, Ningyu Liu, Levi D. Boggs, Steven A. Cummer
Observation-Constrained Modeling Of The Ionospheric Impact Of Negative Sprites, Ningyu Liu, Levi D. Boggs, Steven A. Cummer
Aerospace, Physics, and Space Science Faculty Publications
This paper reports observation and modeling of five negative sprites occurring above two Florida thunderstorms. The sprites were triggered by unusual types of negative cloud-to-ground (CG) lightning discharges with impulse charge moment change ranging from 600 to 1300 C km and charge transfer characterized by a timescale of 0.1-0.2 ms. The negative sprite typically consists of a few generally vertical elements that each contain a bright core and dimmer streamers extending from the core in both downward and upward directions. Modeling results using the measured charge moment change waveforms indicate that the lower ionosphere was significantly modified by the CGs …