## 3 Science Data Product Performance
### The CrIS/ATMS Instruments and Science Data Products  
The CrIS and the ATMS instruments provide IR and MW radiance products (SDRs) for assimilation into NWP models and have shown considerable impact in reducing medium-range forecast errors [1; 74; 75]. In addition to NWP model assimilations, radiance observations from the CrIS and ATMS are used individually and together in the sounding product retrieval algorithms to derive a wide variety of surface and atmospheric sounding products (EDRs) for many atmospheric applications. Many of these EDR products are ingested into the Advanced Weather Interactive Processing System (AWIPS-2 [76]), and Weather Forecasting Offices (WFOs) nationwide utilize these products for analyzing atmospheric instabilities, potential outbreaks of severe weather, and in now-casting applications [77]. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Product** & **Requirement** & **Performance** \\ \hline Snow cover & & \\ Binary Map: \% correct typing & 90\% & 93–94\% \\ Snow fraction: uncertainty & 20\% & \(\sim\)17\% \\ Sea ice & & \\ Ice surface temperature: uncertainty & 1 K & 0.9 K \\ Ice concentration: uncertainty & 10\% & 0.9 K \\ Ice age: \% correct typing & 70\% & 8.9\% \\ Accuracy & Precision & Accuracy & Precision \\ Ice thickness & & 0.5 m \\ VIIRS polar winds & 7.5 m/s & 3.8 m/s & 5.79 m/s & 3.58 m/s \\ \hline \hline \end{tabular}
\end{table} 
Table 8: S-NPP VIIRS cryosphere products performance. Figure 9: The VIIRS Cryosphere products are all operationally produced from the S-NPP and meet APU requirements. (Figure courtesy: [PERSON], STAR Cryosphere team). The CrIS instrument aboard the S-NPP/NOAA-20 is a Fourier Transform Spectrometer (FTS) instrument with channels in three bands covering longwave (LWIR, 650-1095 cm\({}^{-1}\)), midwave (MWIR, 1210-1750 cm\({}^{-1}\)), and shortwave (SWIR 2155-2550 cm\({}^{-1}\)) bands [78]. The instrument is similar to other hyperspectral IR sounding instruments, such as the Infrared Atmospheric Sounding Interferometer (IASI, [79]) and the Atmospheric Infrared Sounder (AIRS, [80,81]). The Advanced Technology Microwave Sounder (ATMS) is a cross-track scanning passive microwave radiometer used to retrieve atmospheric temperature and moisture profiles under clear and cloudy conditions. The instrument has 22 channels spanning 23.8-183.3 GHz and includes most of the channels carried by the Advanced Microwave Sounding Unit (AMSU) and the Microwave Humidity Sounder (MHS or similar instrument such as AMSU-B) instruments flown aboard earlier NOAA polar-orbiting satellites. Details of the ATMS instrument, channel characteristics, calibration and validation of the ATMS SDR products are discussed in detail by [PERSON] et al [15,82]. Figure 10 summarizes ATMS SDR on-orbit NEDT performance and on-orbit biases computed using the European Center for Medium Range Weather Forecasting (ECMWF) forecast/analysis fields. Table 9 shows S-NPP CrIS Nominal Spectral Resolution (NSR) and Full Spectral Resolution (FSR) SDR performance. Until 4 December 2014, the S-NPP CrIS instrument was operated at an NSR of 0.625, 1.25 and 2.5 cm\({}^{-1}\) for LWIR, MWIR and SWIR bands, respectively. Since 4 December 2014, the S-NPP CrIS instrument has been operating in FSR mode with a spectral resolution of 0.625 cm\({}^{-1}\) in all 3 bands, as shown in Figure 11. The NOAA-20 CrIS instrument has been operating in FSR mode since the beginning of the NOAA-20 mission, and the CrIS SDR processing algorithms for both S-NPP and NOAA-20 have adapted the latest calibration algorithms, which contain major changes to the CrIS calibration equation, self-anodization corrections, resampling matrices, and calibration filter [17]. The availability of MW sounding instruments and the utility of the MW retrievals as the initial guess for the hyper-spectral IR sounding retrievals have alleviated cloud-clearing and allowed generation of high-quality geophysical products in scenes with up to 80% cloud cover [80; 83].