TIMED/SEE Solar Spectral Irradiance - Level 4 Spectra
The XPS Level 4 processing algorithm is a model, driven by the SEE XPS 0.1-7 measurement and the GOES XRS ratio. It uses reference CHIANTI spectra to generate a higher spectral resolution (0.1 nm) estimate of the solar XUV irradiance by scaling the model reference spectra to match the XPS photometer currents (signal). Th CHIANTI Quiet Sun (QS) spectrum and Active Region (AR) spectrum are used with a scaling of the AR spectrum to match the minimum signal on each day, and then a CHIANTI isothermal flare spectrum is scaled to match the signal above the daily minimum signal. The flare temperature is determined from the ratio of the GOES XRS 0.1-0.8 nm irradiance to the GOES XRS 0.05-0.4 nm irradiance. These scaling factors, flare temperature, and resulting model spectrum in the 0-40 nm range in 0.1 nm intervals are in the XPS Level 4 data product for every measurement made by XPS photometer #1 or #2 (0.1-7 nm band). The level 4 model product contains daily averages of these results.
The Solar EUV Experiment (SEE) on the TIMED spacecraft has been providing solar spectral irradiance products since February 8, 2002. This data set contains daily averaged spectral irradiance from 0.05 - 39.95 nm.
Note that optically thick emission like He II 30.4 nm are not well represented in this model. Other limitations are due to the nature of the low duty cycle of the SEE XPS measurements which prohibit coronal dimming and the EUV late phase from the model. We recommend using the SDO/EVE high resolution, high cadence solar spectral irradiance measurements since May 2010.
For FTP access to individual files visit the SEE Main Data Page.