A227-0002
Development and Validation of the TSIS-1 Hybrid Solar Reference Spectrum (HSRS)
Wednesday, 16 December 2020
Poster
Odele Coddington1, Erik C Richard1, David Harber1, Peter Pilewskie2, Kelly Chance3, Xiong Liu3 and Kang Sun4, (1)Laboratory for Atmospheric and Space Physics, Boulder, CO, United States, (2)University of Colorado, Laboratory for Atmospheric and Space Physics, Boulder, CO, United States, (3)Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, United States, (4)University at Buffalo, Department of Civil, Structural and Environmental Engineering, Buffalo, NY, United States
Abstract:
State-of-the-art, daily records of solar spectral irradiance (SSI) commenced in 2018 with the Spectral Irradiance Monitor (SIM) on the first Total and Spectral Solar Irradiance Sensor (TSIS-1) mission. Technological advances provide a higher performance SSI dataset than previously attained. The TSIS-1 SIM absolute scale has been validated to much better than 0.3% accuracy over the majority of the spectrum. Since 2019, SSI observations have also been made by a compact SIM (CSIM) instrument for a NASA In-Space Validation of Earth Science Technologies (InVEST) technology demonstration mission. CSIM observations have been verified by TSIS-1 SIM and they have a broader spectral range in the near-infrared relative to TSIS-1 SIM, extending to 2800 nm from 2400 nm. Differences between TSIS-1 SIM or CSIM and other commonly used reference spectra can reach, or exceed, 10% in the ultraviolet portion of the spectrum and approach 8% in the near-infrared.
We have incorporated our new understanding of the absolute scale of the solar spectrum into a solar reference spectrum representing a period of quiet solar activity, with associated uncertainties and at several spectral and sampling resolutions. Since some remote sensing applications, such as trace gas retrievals, require a reference spectrum of much higher spectral resolution than can be obtained by the SIM instruments alone, our reference spectrum is developed by re-normalizing independent, very high spectral resolution datasets to the TSIS-1 SIM absolute irradiance scale. Specifically, 1) solar irradiance data from the Airforce Geophysical Laboratory (AFGL) and the Quality Assurance of Ultraviolet Measurements In Europe Fourier Transform Spectroradiometer (QASUMEFTS) and 2) solar transmittances from the Kitt Peak National Observatory (KPNO) and the Solar Pseudo-Transmittance Spectrum (SPTS).
The TSIS-1 Hybrid Solar Reference Spectrum (TSIS-1 HSRS) spans 202 nm to 2730 nm, with the extension from 2400 nm attributed to CSIM. In this work, we discuss the development and uncertainties of the TSIS-1 HSRS and demonstrate that it is consistent with the TSIS-1 SIM and CSIM solar irradiance scale. Additionally, we compare the TSIS-1 HSRS against independent ground- and space-based solar spectral observations.
