## 5 Summary and Conclusions  
The conversion of shortwave radiance observed by ERB satellite instruments to shortwave irradiance is an essential processing step to obtain the energetically relevant data needed to monitor and understand our climate system. The related underlying theory has been leveraged to develop models over a series of decades that provide a route to convert between radiance and irradiance, known as ADMs. An empirical approach has traditionally been taken to generate ADMs: radiances collected over an extended time period at a large range of solar-viewing geometries are sorted into angular bins and averaged, a process that is performed separately for scene types with distinct anisotropy. As  
Figure 11: Semi-physical ADMs incorporate cloud-top effective radius \(R_{e}\). (**a**) Sensitivity of shortwave anisotropic factors to viewing zenith angle for varying \(R_{e}\) in the principal plane for solar zenith angle bin 20\({}^{\circ}\)–22\({}^{\circ}\) and a cloud optical depth of 10. (**b–d**) Anisotropic factor differences relative to CERES-Terra/Aqua ADMs as a function of \(R_{e}\). Each polar plot contains data for solar zenith angle bin 60\({}^{\circ}\)–62\({}^{\circ}\) and a cloud optical depth of 10 on the left, and solar zenith angle bin 40\({}^{\circ}\)–42\({}^{\circ}\) and a cloud optical depth of 5.5 on the right. In the examples shown, clouds are liquid only, cloud fraction is 100%, and above cloud water vapor is 10 kg m\({}^{-2}\). Reproduced and adapted from [PERSON] et al. [72] and [PERSON] et al., [74] © American Meteorological Society. Used with permission. the ERB observing system has evolved over time, instruments have observed for longer duration and have flown with more advanced imagers, leading to a substantial increase in the complexity and capability of shortwave ADMs over time. Early analyses applied to ERB observations from the 1960s and 1970s, including instruments on the TIROS and Nimbus series of satellites, were relatively coarse in their treatment of the angular distribution of reflected shortwave radiation. It was first noted that variations in solar zenith angle could significantly alter the reflectance of an identical scene, followed by recognition that the shortwave anisotropy depends on the scene properties themselves. By the end of the Nimbus ERB record, the anisotropy of a handful of scene types were treated separately, including dynamic cloud identification that was a major step forward due to the distinct anisotropy presented by clouds. Shortwave ADMs applied during the subsequent ERBE mission additionally accounted for variations in cloud fraction to better represent the relative contribution of cloudy and cloud-free portions of a scene. Of note, the cloud fraction was retrieved using only the ERBE shortwave and longwave radiances. The following CERES mission, which is continuing to provide ERB observations at the time of writing this paper, instead takes advantage of co-flying imagers that were launched along with the CERES instruments. The extended CERES data record of over 20 years has provided multiple generations of shortwave ADMs. CERES-TRMM ADMs involved further segregation of scene types by new variables including cloud optical depth, cloud phase, and surface wind speed over cloud-free ocean. CERES-Terra ADMs extended this approach using observations with global coverage over multiple years, and introduced cloudy ADMs that are continuous in scene type. The most recent CERES-Terra/Aqua ADMs incorporate further updates including segregation by aerosol amount and type over cloud-free ocean, the effects of sastrugi, and variations in sea ice brightness. Validation efforts have shown progressively lower uncertainty in radiance to irradiance conversion with each generation of shortwave ADMs. In addition, the ADMs from CERES have been successfully adapted and applied to observations from other ERB instruments, including those in drastically different orbits.