The Analysis of the Positioning Accuracy of ISUAL

Abstract

The Imager of Sprites and Upper Atmospheric Lightning (ISUAL) on the FORMOSAT-2 is the first scientific payload that can make a long-term global observation of the Transient Luminous Events (TLEs) from space and have gotten a large amount of TLEs data in 2004-2016 However the data of ISUAL had a problem with aberration and the positioning accuracy of ISUAL was also unknown In this study the star calibration is used to get the correction polynomial function of aberration and the positioning accuracy is also analyzed by matching ISUAL TLE events with WWLLN lightning events There are 668 elves events matched with the World Wide Lightning Location Network (WWLLN) lightning events in this study The average distance between these matched events is 60 0 km and the standard deviation is 62 5 km; 78% of the distances are less than 80 km The result can be the reference values of the positioning accuracy of ISUAL For the mismatched elves events there is an additional discussion of the cause of mismatching The result shows that the main reason for mismatching may not be associated with the intensity of the far-ultraviolet signal of elves or the type of elves; it is more likely to be related to the detection efficiency of WWLLN With the result of this work the aberration problem of ISUAL can be improved and the positioning accuracy can be understood furthermore as well

Date of Award	2021
Original language	English
Supervisor	Bing-Chih Chen (Supervisor)