Creation of the GSFCSSI2 Composite Solar Spectral Irradiance Data Set

摘要

Solar spectral irradiance (SSI) is a key driver for the Earth's energy budget. Characterizing the spectral and temporal variations in SSI from measurements over multiple decades relies on the creation of a composite SSI product that merges data from multiple instruments. The V1 composite SSI product created by DeLand and Cebula (2008, https://doi.org/10.1029/98JD01204 ) provides daily spectra covering 120–400?nm by combining data from six instruments but ends in July 2005. We have developed an improved composite SSI product, designated GSFCSSI2, that extends to the present by incorporating additional SSI data sets from the NOAA‐16 SBUV/2, Aura Ozone Monitoring Instrument (OMI), and SORCE SOLSTICE instruments. The NOAA‐16 SBUV/2 SSI data set is a new product that fills a data gap at 170–400?nm in 2005–2006, while the Aura OMI SSI data set represents an improvement over previously published measurements and covers the time period 2006–2018. The SORCE SOLSTICE SSI data set provides data coverage down to 120?nm for the time period 2005–2018. The new GSFCSSI2 composite now spans almost 40?years (November 1978–April 2018) and extends observational coverage into the visible region (500?nm) with OMI data. Comparisons with the NRLSSI2 modelled SSI data set show typical agreement to within ±5% between 120 and 170?nm, ±2%–3% between 170 and 300?nm, and ±1.5% or better between 300 and 500?nm. The GSFCSSI2 composite SSI product is an element of the NASA Solar Irradiance Science Team program and can be further improved by incorporating other data sets being produced through that effort. Plain Language Summary Creating a solar spectral irradiance (SSI) data set that covers multiple decades for climate studies requires a compilation of many individual data sets. We have combined measurements from nine separate instruments to create a composite SSI data set that is almost 40?years in length (1978–2018) and covers wavelengths from the far ultraviolet to the visible (120–500?nm). Remaining drifts in individual data sets make it difficult to draw conclusions about possible long‐term trends in our combined SSI product over multiple decades. Nevertheless, our GSFCSSI2 composite SSI product shows good agreement with semiempirical model estimates.