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We analyze continuous multi‐point measurements of electromagnetic field waveforms onboard the Cluster spacecraft in order to contribute to the discussion on sources of plasmaspheric hiss, known as a shaping agent for the Earth radiation belts. In our case study we aim at finding sources of hiss observed close to the geomagnetic equator in the outer plasmasphere on the dayside. We find hiss to be triggered from whistlers of different spectral properties. Whistlers with the lowest observed dispersion arrive to different spacecraft with time delays indicating their origin in the northern hemisphere. Positions of source lightning discharges are then found using the time coincidences with the Word Wide Lightning Location Network data from three active thunderstorm regions in Europe. We find that subionospheric propagation of lightning atmospherics is necessary to explain the observations. Geographic locations of their ionospheric exit points then determine spectral properties of resulting unducted whistlers and triggered hiss. By this well documented chain of events starting with a lightning discharge in the atmosphere we confirm that magnetospherically reflecting whistlers and hiss triggered from them are among possible sources of plasmaspheric hiss. Key Points: We use multi‐point measurements of electromagnetic field fluctuations by the cluster space fleet to discuss sources of plasmaspheric hissOur case study shows hiss which was triggered in the dayside outer plasmasphere by unducted whistlers emitted from strong lightning strokesSpectral properties of magnetospherically reflecting whistlers and hiss strongly depend on geographical location of the source thunderstorm [ABSTRACT FROM AUTHOR]

This paper discusses my recollections concerning the origins of space radio and plasma wave research at the University of Iowa. My career in space research started when I was hired as a freshman engineering student by Prof. James A. Van Allen in April 1958, shortly after his discovery of Earth's radiation belts with Explorer 1, the first U.S. satellite. My early work mainly involved digital data system designs for the University of Iowa "Injun" series of satellites, the first satellites completely designed and constructed at a university. It was on Injun 3 that, at the suggestion of Prof. Brian J. O'Brien, I developed one of the very first radio and plasma wave instruments ever flown on a spacecraft. This instrument made the first pioneering studies of a wide variety of space radio and plasma wave phenomena, such as whistlers, chorus, and auroral hiss. These early studies were soon followed by somewhat similar NASA‐funded Iowa radio and plasma wave instruments that were used to explore Earth's magnetosphere with the Injun‐5, S3‐A, Hawkeye, IMP, and ISEE satellites, the solar wind with the Helios 1 and 2 spacecraft, and the outer planets and interstellar space with the Voyager 1 and 2 spacecraft. My discussions of this very early era in space research, and the key people involved, are limited to the time period before roughly 1980. Key Point: An overview is presented of the origins of space radio and plasma wave research at the University of Iowa [ABSTRACT FROM AUTHOR]

Abstract: During the Juno perijove explorations from 27 August 2016 through 1 September 2017, strong electromagnetic impulses induced by Jupiter lightning were detected by the Microwave Radiometer (MWR) instrument in the form of 600‐MHz sferics and recorded by the Waves instrument in the form of Jovian low‐dispersion whistlers discovered in waveform snapshots below 20 kHz. We found 71 overlapping events including sferics, while Waves waveforms were available. Eleven of these also included whistler detections by Waves. By measuring the separation distances between the MWR boresight and the whistler exit point, we estimated the distance whistlers propagate below the ionosphere before exiting to the magnetosphere, called the coupling distance, to be typically one to several thousand of kilometers with a possibility of no subionospheric propagation, which gives a new constraint on the atmospheric whistler propagation. [ABSTRACT FROM AUTHOR]

Abstract: The Mars Initial Reference Ionosphere (MIRI) model is a semiempirical formulation designed to provide climatological estimates of key parameters of the Martian ionosphere. For the new MIRI‐2018 version, an expanded database is used from the Mars Express/Mars Advanced Radar for Subsurface and Ionosphere Sounding/Active Ionospheric Sounding (MEX/MARSIS/AIS) instrument, consisting of 215,818 values of maximum electron density of the M2‐layer (NmM2) from the years 2005–2015. These data are organized by photochemical‐equilibrium equations to obtain a functional dependence of NmM2 upon solar drivers (flux and solar zenith angle). The resulting peak density is used to calibrate normalized electron density profiles [Ne (h)] derived from theory and an empirical model. The MIRI‐2018 thus provides estimates of NmM2, Ne (h), and total electron content (TEC) for any date past or future. Validation using Mars Atmosphere and Volatile EvolutioN (MAVEN)'s new radio occultation science experiment (ROSE) was successful for NmM2 values, but MIRI was found to overestimate TEC values. The validation failure for TEC was traced to overestimates of plasma at low altitudes (M1 layer). A separate module for TEC was derived using 126,055 values from the Mars Reconnaissance Orbiter/SHAllow RADar (MRO/SHARAD) TEC database from 2006 to 2014. Validation of this new TEC module with ROSE data was successful. Future improvements to MIRI‐2018 require new ways to characterize the bottomside ionosphere's contribution to the TEC integral for midday (low solar zenith angle) conditions. This requires new simulation studies of secondary ionization rates by photoelectrons produced via the primary X‐ray ionization process for the M1 layer. [ABSTRACT FROM AUTHOR]