New models of the Sun's irradiance variability are developed from 15 years of direct observations made by the Solar Radiation and Climate Experiment (SORCE) spacecraft from 2003 to 2017 (inclusive). Multiple linear regression parameterizes the observations in terms of facular brightening and sunspot darkening, which are the primary sources of solar irradiance variability. The facular influence is specified as a combination of a linear and nonlinear solar ultraviolet (UV) index; the addition of the nonlinear term allows better reproduction of concurrent solar cycle and rotational variability. The sunspot darkening index is calculated using sunspot observations from both the Debrecen catalog and Air Force Solar Observing Optical Network (SOON) operational sites, the former providing superior model performance. The new model of total solar irradiance variability, NRLTSI3, with the Debrecen sunspot index reproduces the direct Total Irradiance Monitor (TIM) observations better than does the NRLTSI2 model that currently specifies irradiance for the NOAA Climate Data Record (CDR); the correlation of the model and observations increases from 0.956 to 0.971, and the standard deviation of the residuals decreases from 0.124 to 0.100 W m⁻². The new model of solar spectral irradiance variability, NRLSSI3, which extends from 115 to 100,000 nm, reproduces rotational modulation in independent Ozone Monitoring Instrument (OMI) observations at near‐UV and visible wavelengths. The SATIRE model overestimates rotational modulation of near‐UV Fraunhofer spectral features because of excess facular brightness; the EMPIRE model overestimates rotational modulation at all near‐UV wavelengths.

中文翻译：

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太阳辐照度变异性：对测量建模

太阳辐照度可变性的新模型是根据太阳辐射与气候实验（SORCE）航天器从2003年至2017年（含）进行的15年直接观察得出的。多元线性回归将参数化为观测值，即增白和黑子变黑，这是太阳辐照度变化的主要来源。局部影响被指定为线性和非线性太阳紫外线（UV）指数的组合；非线性项的添加可以更好地再现同时发生的太阳周期和旋转变化。利用从德布勒森目录和空军太阳观测光网络（SOON）操作站点获得的黑子观测值计算出黑子变暗指数，前者可提供出色的模型性能。与德布勒森太阳黑子指数有关的新的总太阳辐照度变化模型NRLTSI3可以比目前为NOAA气候数据记录（CDR）指定辐照度的NRLTSI2模型更好地再现直接的总辐照度监测器（TIM）观测值；模型与观测值的相关性从0.956增大到0.971，残差的标准偏差从0.124减小到0.100 W m⁻²。太阳光谱辐照度可变性的新模型NRLSSI3从115 nm扩展到100,000 nm，可在独立的臭氧监测仪（OMI）观测中在近紫外和可见光波长下再现旋转调制。SATIRE模型由于过分的人眼亮度而高估了近紫外Fraunhofer光谱特征的旋转调制。EMPIRE模型高估了所有近紫外波长的旋转调制。