Updates in SDO/EVE/EUV SpectroPhotometer (ESP) Data Processing and Inter-comparison of Calibrated ESP Irradiances with Measurements from Other On-orbit EUV Instrumentation

Monday, 15 December 2014
Seth R Wieman, University of Southern California, Los Angeles, CA, United States, Leonid V Didkovsky, Univ of Southern California, Los Angeles, CA, United States and Donald Woodraska, Univ Colorado, Boulder, CO, United States
Prior to the May 2014 anomaly which indefinitely suspended SDO/EVE Multiple EUV Spectrographs-A (MEGS-A) science operations, MEGS-A spectral distributions were used in the data processing algorithm for determining absolute EUV irradiance values from the SDO/EVE EUV Spectrophotometer (ESP) raw data. We discuss a revised ESP data processing algorithm which, in lieu of concurrently measured MEGS-A spectra, adopts reference spectra selected (based on solar activity at the time of the ESP observation) from a discrete set of spectra derived from MEGS-A spectra for various levels of activity observed prior to the anomaly. We present evaluations of the revised algorithm and adopted reference spectra based on comparisons of the resultant ESP irradiance values with EUV measurements from other on-orbit instrumentation including the SOHO/Solar EUV Monitor (SEM). The results of comparisons between ESP irradiances determined using the revised algorithm and those based on the pre-anomaly algorithm which uses concurrent MEGS‑A spectra are also presented