Converting TREx-RGB green-channel data to 557.7 nm auroral intensity:Methodology and initial results

作     者：Jun Liang D.M.Gillies E.Spanswick E.F.Donovan Jun Liang;D.M.Gillies;E.Spanswick;E.F.Donovan

作者机构：University of CalgaryCalgaryT2N 1N4Canada 

出 版 物：《Earth and Planetary Physics》 (地球与行星物理（英文版）)

年 卷 期：2024年第8卷第1期

页      面：258-274页

核心收录：

学科分类：07[理学] 070802[理学-空间物理学] 0708[理学-地球物理学] 

基　　金：jointly funded by the Canada Foundation for Innovation the Alberta Economic Development and Trade organization the University of Calgary supported by the Canadian Space Agency。 

主　　题：TREx RGB green-line aurora auroral transport model 

摘      要：The recently deployed Transition Region Explorer(TREx)-RGB(red-green-blue)all-sky imager(ASI)is designed to capture“true colorimages of the aurora and airglow.Because the 557.7 nm green line is usually the brightest emission line in visible auroras,the green channel of a TREx-RGB camera is usually dominated by the 557.7 nm emission.Under this rationale,the TREx mission does not include a specific 557.7 nm imager and is designed to use the RGB green-channel data as a proxy for the 557.7 nm aurora.In this study,we present an initial effort to establish the conversion ratio or formula linking the RGB green-channel data to the absolute intensity of 557.7 nm auroras,which is crucial for quantitative uses of the RGB data.We illustrate two approaches:(1)through a comparison with the collocated measurement of green-line auroras from the TREx spectrograph,and(2)through a comparison with the modeled green-line intensity according to realistic electron precipitation flux measurements from low-Earth-orbit satellites,with the aid of an auroral transport model.We demonstrate the procedures and provide initial results for the TREx-RGB ASIs at the Rabbit Lake and Lucky Lake stations.The RGB response is found to be nonlinear.Empirical conversion ratios or formulas between RGB green-channel data and the green-line auroral intensity are given and can be applied immediately by TREx-RGB data users.The methodology established in this study will also be applicable to the upcoming SMILE ASI mission,which will adopt a similar RGB camera system in its deployment.