Adapting NUCAPS Operational System to Generate NOAA Unique Products from MetOp-SG IASI-NG Hyperspectral Sounder: Algorithm Development, Optimization, and Augmentation Using Proxy/Synthetic Datasets

The NOAA Unique Combined Atmospheric Processing System (NUCAPS) is currently the National Oceanic and Atmospheric Administration (NOAA) operational hyper-spectral sounding product system for deriving hyper-spectral radiance products, vertical profiles of temperature, water vapor, ozone, and six trace gas products (CO, CH4, CO2, Volcanic SO2, HNO3 and N2O). The algorithm is built on the heritage from the Atmospheric Infrared Sounder (AIRS) science team algorithm. The NOAA center for Satellite Applications and Research (STAR) has implemented the NUCAPS enterprise algorithm to produce a large array of operational products from the Suomi-NPP/NOAA-20 (1:30 AM/PM orbit) Cross-track Infrared Sounders (CrIS), and from the Infrared Atmospheric Sounder (IASI) instruments aboard the Meteorological Operational Satellite Program (MetOp-A,B,C, 9:30 AM/PM orbit) series of satellites. The algorithm uses the Advanced Technology Microwave Sounder aboard S-NPP/NOAA-20 and the Advanced Microwave Sounding Unit-A/Microwave Humidity Sounder aboard the MetOp series to both produce an initial guess for the hyper-spectral IR sounding retrievals, and to assist in generating high-quality geophysical products in scenes with up to 80% cloud cover. Numerical Weather Prediction Centers worldwide access and assimilate several NUCAPS derived hyperspectral radiance products, such as the thinned radiance data sets, principal component scores, and cloud-cleared radiances, etc. The Weather Forecast Offices nationwide ingest NUCAPS EDR products into the Advanced Weather Interactive Processing System (AWIPS-2) for analyzing atmospheric instabilities, potential outbreaks of severe weather, and in now-casting applications.

In pursuance on the use of European Organisation for the Exploitation of Meteorological Satellite Second Generation (EUMETSAT-SG, expected launch in 2022) IASI Next Generation (IASI-NG) hyperspectral observations, NOAA STAR has initiated refinements to the NUCAPS algorithm to produce NOAA unique products from the IASI-NG and accompanying Microwave Sounder (MWS). This paper presents the on-going efforts in setting up a NUCAPS-NG EDR product development system using proxy/synthetics data sets provided by the EUMETSAT and generated at STAR for the IASI-NG and MWS instruments. In addition to augmenting the NUCAPS system using the IASI-NG proxy/synthetic data sets (0.125 cm-1, 16,921 channels, 4 x 4 field of views, FOVs), the high spectral resolution Fourier Transform Spectrometer data are transformed into various sensor/instrument configurations, such as (a) CrIS (0.625 cm-1, 2211 channels, 3 x 3 FOVs) and (b) current IASI (0.625 cm-1, 8461 channels with 2 x2 FOVs). Similarly, the MWS data are transformed into ATMS/AMSU-A/MHS field of regards (FOR) following sensor geometry/collocation criteria between hyperspectral IR sounders and the microwave instruments. NUCAPS EDR products generated for these instrument configurations are evaluated for relative performance assessment from these instrument configurations. This paper presents preliminary results on information content with different sets of spectral channels, cloud-clearing improvements realizable with different FOV configurations within the FOR retrievals, and assessment of both the NUCAPS first guess and the final physical retrieval products with the available instrument characteristics. The augmentation of the current NUCAPS system for the IASI-NG, along with the analysis tools adapted for IASI-NG, will help to alleviate any issues in the implementation and provide realistic results when applied to improved proxy data sets expected in the future for pre-launch characterization of the NUCAPS IASI-NG EDR products.