Uncertainties in the facular and sunspot proxy indices input to the model are the largest sources of uncertainty in the modeled irradiance variability.
Second, the spectrally integrated facular brightening and sunspot darkening components of the modeled SSI are compared with their TSI model counterparts.
Facular brightening and sunspot darkening activity were relatively high in late October 2003 and the rapid short-term decrease in TSI evident in Fig.
The newly formulated NRLTSI2 and NRLSSI2 models differ from the original NRL models of solar irradiance variability in several significant ways including the quiet sun reference spectrum (see the "adopted quiet sun reference" section), the records of TSI and SSI observations used in multiple linear regressions to establish the scaling coefficients (see the "model scaling coefficients" section), and in the sunspot and facular proxy indices (see the model inputs and ancillary data section).
2000) were used to represent the wavelength dependence of sunspot and facular contributions (Lean 2000; Lean et al.
In the future, new versions of the Solar Irradiance CDR are expected to accrue from the TSIS observational record of TSI and SSI, which will permit validation and modification, as necessary, of the associations of solar irradiance variability with the facular and sunspot proxy indices.
To facilitate validation with independent datasets, the time series of the facular brightening and sunspot darkening proxy inputs are also archived at NCEI, with updates at the same cadence as the solar irradiance files.
9 provides an overview of the algorithm processing steps to calculate TSI and SSI at a specified time using procedures that are 100% numerically reproducible given identical sunspot darkening and facular brightening inputs.
The availability of the proxy data used to compute the facular brightening and sunspot darkening indices determines the latency of the updates for the Solar Irradiance CDR.
Deviations from expected or predicted values, flagging of anomalous values, and trending of the sunspot blocking function and facular brightening function relative to independent proxies of solar variability as well as trends in final science values relative to independent models and measurements of solar irradiance are all incorporated into the assessment of the stability in the final science data products.