Modeling Solar Irradiance With the PSPT Solar Disk Observations and RISE Solar Spectrum Synthesis

Author: Sean Davis (1), J. Fontenla (1), J. Harder (1), G. Rottman (1), and R. Meisner (2)
Affiliations: 1) LASP, University of Colorado 2) High Altitude Observatory / NCAR

The PSPT (Precision Solar Photometric Telescope) at the Mauna Loa Solar Observatory produces full disk solar images in the Ca II-K spectral line (393 nm ? 0.15 nm), blue (409.3 nm ? 0.15 nm) continuum, and red (607.2 nm ? 0.15 nm) continuum, with ~0.1% photometric precision and 1 arc sec pixels. The RISE (Radiative Inputs of the Sun to Earth) spectral synthesis calculation is based on 7 solar atmosphere models corresponding to quiet and active solar features, and currently calculates the emitted intensity as a function of wavelength from 0.5 to 10 micron for 10 positions in the solar disk. We use the RISE-derived center-to-limb variation functions for each surface feature in the instrument spectral band to extract the feature distribution on the solar surface corresponding to each PSPT image. The average disk intensity as a function of wavelength is then constructed using the RISE calculated spectra for each feature and position on the disk. We present the results of a preliminary study of solar irradiance calculations and comparisons with measurements from the Solar Radiation and Climate Experiment (SORCE) satellite. These comparisons are made with the Spectral Irradiance Monitor (SIM), which measures spectral irradiance (200 nm – 2700 nm). In addition to the preliminary results, we present future plans for comparisons with SIM data.