1:45 PM - 3:15 PM
[O07-P49] Relationship between sprites and the lightning charge moment
Keywords:TLEs, Lightning
We are studying the phenomenon of sprites. Sprites are a kind of Transient Luminous Events, and Transient Luminous Events are luminescence phenomena that occur with lighting in the mesosphere at an altitude of about 50 to 100 kilometers. The mechanism of sprites is as follows. A positive polarity lightning strike neutralizes the positive charge in the upper layers of the cloud, and a downward electric field is generated from the ionosphere toward the upper cloud layer. The electric field causes electrons at an altitude of around 60 kilometers to rise and collide with nitrogen atoms, putting them in an excited state. Sprites occur as a result of the release of energy when these nitrogen atoms return to their ground state. However, not all positive polarity lightning strikes produce sprites. We investigated relationship between the charge moment of the lightning and sprites to clarify the conditions for its occurrence. The charge moment is a value defined as the product of the amount of charge discharged by lightning and the altitude, and there is a paper that says this value is large for lightning that generates sprites. We tested whether this was also true for our own data. We have data on the images and locations of sprites when they occurred. By acquiring the data, the time and location of the lightning, and the magnetic field data from the electromagnetic waves generated by the lightning, we analyzed the charge moments of the lightning that generated sprites and the lightning that did not, and compared them to see if there was any difference.
As a method of verification, we first identified the location of the sprite's occurrence using data taken from multiple observation points. The next step was to identify the lightning, the thunderbolt that generated the sprite. Finally, we compared the size of the lightning charge moment at the time of sprite generation. It is not possible to directly determine the value of the lightning charge moment but the strength of the magnetic field of electromagnetic waves generated by lightning is proportional to the lightning charge moment. Therefore, we analyzed the relationship between the magnitude of the magnetic field strength and the magnitude of the lightning charge moment.
This section describes how to analyze the location of sprite generation. We are observing the high-altitude luminescence phenomenon together with 32 high schools in Japan. And in the observed data, there are successful events observed simultaneously from two or more locations. The position and direction of these sprites were identified by referring to the stars in the same location.
Next, we found the lightning at the time when the sprite occurred and timed the two data sets to identify the lightning. We obtained information on lightning from several companies and research institutes, and identified lightning from lightning that occurred at the same time when the sprites occurred.
Then, Chubu University provided us with data on the strength of the magnetic field of the electromagnetic waves generated by lightning. Thanks to the data, we compared the integrated magnetic field values for lightning with sprites and without them.
As a method of verification, we first identified the location of the sprite's occurrence using data taken from multiple observation points. The next step was to identify the lightning, the thunderbolt that generated the sprite. Finally, we compared the size of the lightning charge moment at the time of sprite generation. It is not possible to directly determine the value of the lightning charge moment but the strength of the magnetic field of electromagnetic waves generated by lightning is proportional to the lightning charge moment. Therefore, we analyzed the relationship between the magnitude of the magnetic field strength and the magnitude of the lightning charge moment.
This section describes how to analyze the location of sprite generation. We are observing the high-altitude luminescence phenomenon together with 32 high schools in Japan. And in the observed data, there are successful events observed simultaneously from two or more locations. The position and direction of these sprites were identified by referring to the stars in the same location.
Next, we found the lightning at the time when the sprite occurred and timed the two data sets to identify the lightning. We obtained information on lightning from several companies and research institutes, and identified lightning from lightning that occurred at the same time when the sprites occurred.
Then, Chubu University provided us with data on the strength of the magnetic field of the electromagnetic waves generated by lightning. Thanks to the data, we compared the integrated magnetic field values for lightning with sprites and without them.