NRL Solar Spectral Irradiance (NRLSSI) Model

Dr. Judith Lean has developed the NRL Solar Spectral Irradiance (NRLSSI) Model that is applicable for Earth’s climate and atmosphere research. This model is empirically derived using proxies of sunspot area and facular brightening and validated with SSI measurements. Her model results include different time periods (e.g. 1950-2008), different time resolution (e.g, daily, monthly), and different wavelength regions (e.g., ultraviolet, visible).

The NRLSSI model covers the wavelength range from 120 nm in the ultraviolet (UV), through the visible (VIS), and up to 100 microns (100000 nm) in the infrared (IR). The model spectra have spectral bin widths increasing from 1 nm at 120.5 nm to 25 nm at 99.975 microns, for which estimates of the solar spectral irradiance are determined daily since 1950, monthly since 1882 and annually since 1610.

The model results can be obtained from the Solar Influence for SPARC (SOLARIS) web site at the Freie Universitat in Berlin. The SOLARIS web site serves SSI model files and provides a more detailed description and references for Judith Lean’s SSI models.

Dr. Judith Lean has developed the NRL Solar Spectral Irradiance (NRLSSI) Model that is applicable for Earth’s climate and atmosphere research. This model is empirically derived using proxies of sunspot area and facular brightening and validated with SSI measurements. Her model results include different time periods (e.g. 1950-2008), different time resolution (e.g, daily, monthly), and different wavelength regions (e.g., ultraviolet, visible). The NRLSSI model covers the wavelength range from 120 nm in the ultraviolet (UV), through the visible (VIS), and up to 100 microns (100000 nm) in the infrared (IR). The model spectra have spectral bin widths increasing from 1 nm at 120.5 nm to 25 nm at 99.975 microns, for which estimates of the solar spectral irradiance are determined daily since 1950, monthly since 1882 and annually since 1610. The model results can be obtained from the Solar Influence for SPARC (SOLARIS) web site at the Freie Universitat in Berlin. The SOLARIS web site serves SSI model files and provides a more detailed description and references for Judith Lean’s SSI models. More information about this model is provided in Lean et al. (2005). For questions about this model please contact Judith Lean. For questions about the SOLARIS web site please contact Katja Matthes.

The solar spectral irradiance (SSI) is shown in the top-left plot, both as the top of the atmosphere (TOA) irradiance in blue and as the surface irradiance in orange. The key molecular absorbers in the atmosphere are indicated at the top of this SSI figure. All of the radiation shortward of 300 nm is absorbed in Earth’s atmosphere; this atmospheric absorption is shown as a function of wavelength and altitude in the bottom-middle plot. Earth’s atmospheric layers are heated due to this solar ultraviolet (UV) radiation, and the atmosphere’s temperature profile is shown in the bottom-right figure. The top-left figure also shows (in green) the percentage changes in the solar spectral irradiance during the 11-year solar activity cycle, estimated by the NRLSSI model.
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