The SORCE SIM Instrument: Progress Toward Spectral Irradiance Time Series Throughout the 300-3000 nm Region

Authors: Jerald Harder, Juan Fontenla, Byron Smiley, George Lawrence, and

Gary Rottman

Affiliation: LASP, University of Colorado

The SIM instrument (Spectral Irradiance Monitor) is a dual prism spectrometer that operates throughout the visible and NIR spectral regions with a 200-300 nm channel that operates concurrently with the MUV channel of SOLSTICE. For this presentation we will discuss the instrument capabilities of SIM by discussing the optical properties of the spectrometer, the Electrical Substitution Radiometer, the operation modes, and the instrument’s output data. The SIM instrument also provides a measurement of the solar spectrum throughout its operating range and also gives the time series of solar variability at any wavelength in its optical passband. We will present a comparison of the SIM spectrum relative to other published spectra and will show how solar variability affects this spectrum over time frames of a solar rotation period. We will also discuss other important topics for the use of the SIM instrument such as optical degradation and detector stability.