P51B-3940:
FISM-P: A Model of the Vacuum Ultraviolet Irradiance Spectrum for Atmospheric Studies at Mars and Beyond
Friday, 19 December 2014
Edward Thiemann, Laboratory for Atmospheric and Space Physics, Boulder, CO, United States, Francis Gerard Eparvier, University of Colorado at Boulder, Boulder, CO, United States and Phillip C Chamberlin, NASA Goddard Space Flight Center, Greenbelt, MD, United States
Abstract:
The MAVEN probe includes the EUV instrument, which will be used to produce a model of the vacuum ultraviolet (VUV: 0-190 nm) spectrum at Mars. This VUV irradiance model is an iteration of the Flare Irradiance Spectral Model (FISM), an empirical model of the solar irradiance spectrum from 0.1 to 190 nm at 1 nm spectral resolution with a 1 minute time cadence. This latest iteration is called FISM-P, where the ‘-P’ suffix stands for ‘planetary’, and estimates mean daily irradiances from 0.1 to 190 nm for every planet in the solar system from 1948 to the present through weighted interpolation of earth measured proxies. In addition to daily irradiances, planetary 1-minute (flaring) irradiances are available if the planet is positioned such that the flaring emissions are observed by instruments at Earth or MAVEN EUV at Mars. FISM is optimized to use the best available proxies for each layer of the solar atmosphere (chromosphere, transition region, cool corona, and hot corona). FISM-P uses both interpolated earth proxies (the MgII core-to-wing ratio, H Ly-a and F10.7) and, when available, the MAVEN EUV measurements (H Ly-α, 17-22 nm, and 0-6 nm) for improved accuracy at Mars. FISM has already been successfully used as an input for ionospheric and thermospheric models for Earth, Mars, as well as comparisons of photoelectrons at Earth and Mars, and surface charging of the moon. FISM-P now provides the capability for similar studies throughout the solar system; and the in situ VUV measurements by MAVEN EUV will result in the most accurate VUV spectrum to date at Mars.
