Global transients in ultraviolet and red‐infrared ranges from data of Universitetsky‐Tatiana‐2 satellite

Abstract

[1] Light detectors sensitive to wavelength ranges 240-400 nm and beyond 610 nm (which we refer to, for simplicity, as the UV and Red bands) on board UniversitetskyTatiana-2 satellite have detected transient flashes in the atmosphere of duration 1-128 ms. Measured ratio of the number of Red photons to the number of UV photons indicates that source of transient radiation is at high atmosphere altitude (>50 km). Distribution of events with various photon numbers Q a in the atmosphere found to be different for "luminous" events Q a = 10 23 -10 26 (with exponent of differential distribution -2.2) and for "faint" events Q a = 10 21 -10 23 (with exponent À 0.97). Luminous event parameters (atmosphere altitude, energy released to radiation, and temporal profiles) are similar to observed elsewhere parameters of transient luminous events (TLE) of elves, sprites, halo, and gigantic blue jets types. Global map of luminous events demonstrates concentration to equatorial zones (latitudes 30 N to 30 S) above continents. Faint events (with number of photons Q a = 10 20 -5Á 10 21 ) are distributed more uniformly over latitudes and longitudes. Phenomenon of series of transients registered every minute along satellite orbit (from 3 to 16 transients in one series) was observed. Most TLE-type events belonged to series. Single transients are in average fainter than serial ones. Some transients belonging to series occurs far away of thunderstorm regions. Origin of faint single transients is not clear; several hypothetical models of their production are discussed.Citation: Garipov, G. K. et al. (2013), Global transients in ultraviolet and red-infrared ranges from data of Universitetsky-Tatiana-2 satellite,

“Lomonosov” Satellite—Space Observatory to Study Extreme Phenomena in Space

“…Analysis of correlation between clouds and any TAE (in series or not) is also in contradiction to the lightning origin of some TAE. An equal numbers of transients in both cloudy and cloudless areas of the atmosphere (Vedenkin et al 2011;Garipov et al 2013) were observed, while lightning was strongly correlated to clouds. Those data will be confirmed by new measurements with better identification of TAE and lightning.…”

“…One can see that short transients are numerous and have fewer UV photons than longer ones. It was also shown in Garipov et al (2013) that short TAE are not concentrated to equatorial latitudes as longer ones. Whether this is a triggering effect or a physical phenomenon will be clarified during measurements onboard the Lomonosov satellite.…”

“…For T = 60 s in Tatiana-2, the experiment "threshold" Q ath in photon number distribution was Q ath = 10 21 (Garipov et al 2013), while in the Vernov experiment (T = 4.5 s) Q ath is shifted to 10 20 . In the upcoming TUS experiment, the threshold photon number is expected to be ∼ 10 17 -close to the fluorescence photon number in EAS of GZK (Greisen-Zatsepin-Kuzmin) energies.…”

“…Aiming to fulfil both tasks: measurement of transient events as a background for planning fundamental physics experiment on the highest energy cosmic rays and study of geophysical problem figure) and lightning below it (Kuo et al 2007) of global electric circuit, UV fluorescence detectors were put on boards of several MSU microsatellites. They are "Universitetsky-Tatiana" (Sadovnichy et al 2007;Garipov et al 2005, "Universitetsky-Tatiana-2" (Sadovnichy et al 2011;Vedenkin et al 2011;Garipov et al 2013) and "Vernov" (Panasyuk et al 2016). Their data will be widely used in this review.…”

“…13, demonstrates strong correlation of TAE with lightning map-most of events are above continents in equatorial regions of the Earth. Data on ratio of TAE intensity in UV and Red-infrared bands (available in Tatiana-2 experiment Sadovnichy et al 2011;Vedenkin et al 2011;Garipov et al 2013) favor the transient origin of registered events-not lightning itself. This conclusion is based on temporal structure of events and their spectrum different from lightning spectrum (measured in Orville and Henderson 1984) and closer to sprite spectrum (Milikh et al 1997).…”