No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
TARANIS : a Project of Microsatellite for the Study of Sprites and Associated Emissions
Abstract
Taranis (Tool for the Analysis of RAdiations from lightNIngs and Sprites) is a CNES microsatellite project which will be in phase A in 2005. It proposes to measure sprites, halos, jets and elves and the associated terrestrial and X ray flashes, electromagnetic and electrostatic emissions, and energetic electrons at the nadir above thunderstorm. These complementary measurements will be carried on a local and global scale in order to understand the physical mechanisms responsible for the impulsive transfers of energy between the neutral atmosphere and plasmas of the ionosphere and magnetosphere. The purpose is to study the coupling between the low and middle atmosphere, the thermosphere, the ionosphere and the magnetosphere. The final goal is to establish the impact of these processes on the Earth's environment. The purpose of the presentation is to describe the project, its scientific objectives, the mission, the scientific payload. The sprite observation method at the nadir by spectral differentiation is already used by the experiment LSO (Lightning and Sprite Observations) on board of the International Space Station.
The experiment LSO (Lightning and Sprite Observations) on board of the International Space Station is the first experiment
dedicated to sprite observations at the nadir. Such observations are difficult because the luminous emissions of sprites and
lightning can be superimposed when they are observed from space at the nadir. Such observations are however needed for measuring
simultaneously all possible emissions (radio, X-γ, high energy electrons) associated with sprites for a better understanding
of the implied mechanisms. They are possible in specific spectral lines where sprites are differentiated from lightning. Absorption
bands of the atmosphere are well adapted for this differentiation because the light emissions from sprites occurring in the
middle and upper atmosphere are less absorbed in these bands than lightning emissions occurring more deeply in the atmosphere.
The most intense spectral emission band of the sprites, corresponding to the N21P band at 761 nm, partly superimposed with the oxygen absorption A band of the atmosphere, is used by the LSO experiment.
The experiment is composed of two micro-cameras, one in the visible and near infra red, the other equipped with an adapted
filter. Only sprites, halos and superbolts, which correspond to a class of rare very intense lightning, are transmitted through
the filter. Sprites, halos and superbolts are identified by the ratio of the intensities received through the filter and in
the whole spectrum. This ratio is lower for superbolts than for sprites and halos. The response of the sprites is also more
complex and variable than the response of superbolts which is very flat and comparable from an event to another. Finally,
LSO observed 17 sprites, 3 halos and 9 superbolts. Several examples of differentiation of sprite and superbolts are given.
The results of a first global statistical study are also presented.
ResearchGate has not been able to resolve any references for this publication.