A237-01
Solar Spectral Irradiance Measurements during Solar Minimum and into Solar Cycle 25: TSIS-1 SSI overlap with SORCE and CSIM-FD SSI
Wednesday, 16 December 2020: 08:30
Virtual
Erik C Richard1, David Harber1, Odele Coddington1,2, Steffen Mauceri3, Peter Pilewskie4, Stephane Beland1, Michael Chambliss2, Steven Victor Penton5, Laura Sandoval1, Jerald William Harder6 and Thomas N Woods7, (1)Laboratory for Atmospheric and Space Physics, Boulder, CO, United States, (2)Laboratory for Atmospheric and Space Physics, Boulder, United States, (3)University of Colorado at Boulder, Laboratory for Atmospheric and Space Physics, Boulder, CO, United States, (4)University of Colorado, Laboratory for Atmospheric and Space Physics, Boulder, CO, United States, (5)University of Colorado Boulder, Laboratory for Atmospheric and Space Physics, Boulder, CO, United States, (6)Univ Colorado, Boulder, CO, United States, (7)University of Colorado Boulder, LASP, Boulder, CO, United States
Abstract:
The continuous, near full spectrum measurement of the solar spectral irradiance (SSI) began with the SORCE mission that launched in Jan. 2003. The SORCE Spectral Irradiance Monitor (SIM) provided the long-term SSI measurements (200 nm – 2400 nm) for 17 years until the completion of the mission in Feb 2020 – a time period that covered the descending phase of solar cycle (SC) 23, through the full SC 24, and to the solar minimum between SC 24 and 25. In Dec. 2017 an improved, second-generation SIM was launched to the ISS as part of the first Total and Spectral Solar Irradiance Sensor (TSIS-1) mission. TSIS-1 SIM became operational in Mar. 2018 and provided early mission overlap with SORCE SIM during the onset of SC 24/25 solar minimum and continues the SSI data record into SC 25. Advancements in instrument design and calibration techniques have resulted in TSIS-1 SIM achieving unprecedented low uncertainties in both absolute accuracy and spectral stability (validated to <0.3% absolute and ~0.01% per year, respectively) over the majority of the spectrum. These temporal and spectral overlapping measurements validate the stability of the SORCE SIM end-of-mission data. We compare the TSIS-1 SIM measurements to both the SORCE SIM observations and the new NRLSSI-3 model results during this solar cycle minimum time period.
During this SORCE / TSIS-1 overlap period, the Compact Spectral Irradiance Monitor Flight Demonstration (CSIM-FD) mission, a 6U CubeSat, successfully launched in Dec. 2018. The CSIM instrument makes daily observations of the solar spectrum across a continuous wavelength region spanning 200 – 2800 nm. CSIM-FD advances new technology and demonstrates the unique capabilities of a complete SSI mission with inherent low mass, low power, and compact design. The CSIM mission has a primary goal of demonstrating SSI-continuity level science capability in a miniaturized and cost-effective package. Operational overlap of CSIM with the TSIS-1 SIM is unique because both of these spectral radiometers have their calibrations and end-to-end validations tied to the same spectral irradiance traceability scale providing on-orbit validation of the absolute SSI uncertainties. The success of the CSIM-FD mission is proving that future small satellite concepts are viable for maintaining critical long-term solar data records.
