A new method to subtract dayglow for auroral observation of SSUSI in LBH ranges based on the improved AURIC

A new method to remove the dayglow components for auroral observations from the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) aboard the Defense Meteorological Satellite Program (DMSP) F16 in Lyman-Birge-Hopfield (LBH) ranges based on the improved Atmospheric Ultraviolet Radiance Integrated Code (AURIC) algorithm is proposed in this study. This method is developed by determining the coefficients between the dayglow intensities calculated by the improved AURIC algorithm and the dayglow components from SSUSI in the whole 2005. The least-square polynomials are used to fit the calculations to the observations and the coefficients of the polynomials are divided by Ap indices and solar zenith angles (SZA). This algorithm can be used to simulate the dayglow intensity in the northern polar region at an altitude of 110 Km. Three examples with Ap indices 5, 27, 154 are tested to verify the effectiveness of the algorithm. The consistency between the original AURIC and the improved AURIC at nadir direction, the derived auroral images and the simulated dayglow images, also the fitting precisions and deviations between the dayglow intensities from improved AURIC and the dayglow intensities from SSUSI, demonstrate that this method is feasible and reliable. The proposed method provides us with a useful tool to separate the dayglow and aurora for space FUV observation.