The NOAA Unique Combined Atmospheric Processing System (NUCAPS): the NOAA operational processor for the new generation of JPSS hyperspectral sounders.

This presentation provides an overview on the recent algorithm development and scientific innovation implemented in the NOAA Unique Combined Atmospheric Processing System (NUCAPS), the NOAA operational processor for the new generation of JPSS hyperspectral sounders. NUCAPS draws on NOAA’s vision for a continued and robust record of environmental data, so as to respond to the nation’s growing need for resilience against extreme weather and climate change.

We, a young team of algorithm developers, are confronted with a great challenge that calls for in-depth knowledge of the many facets related to remote sensing. Our efforts in the most recent months, concentrated on improving the modularity of the NUCAPS algorithm to ensure applicability to multiple sensors: SNPP, the JPSS and Metop constellation and, soon to be launched, the Metop Second Generation. This work recognizes the fact that improved sensor resolution and radiometric noise calls for higher accuracy in all the critical aspects characterizing the modelling of the atmospheric radiative transfer measurement and its inversion techniques. Our initial assessment of NUCAPS retrieved carbon monoxide, methane and carbon dioxide – the three major players of the atmospheric carbon cycle – revealed problematic vulnerabilities in the present algorithm, starting with an insufficient accuracy in the spectroscopy, an instability in the cloud clearing procedure and an archaic climatology in the geophysical a priori constraints. This exercise unfolded a number of key questions that are critical to our mission. How does the long standing uncertainty in the spectroscopy reflect on the performance of the carbon trace gas retrievals and what will be the impact when applied to finer spectral resolution instruments (i.e IASI NG)? Can we separate the spectral cross-talking between atmospheric species (i.e. water vapor and methane) so as to accurately monitor their trends and correctly understand their geophysical correlations? How can we ensure separation of the cloud radiative signal so as to gain more vertical sensitivity down in the boundary layer? Resolving these questions has been the primary driver of this past year’s activities. It required a new critical thinking focused on in depth sensitivity studies, radical algorithm innovations and a dedicated investment on validation. A critical focal point of this activity is primarily the mitigation of all the existing risks associated to the reprocessing plans of the NUCAPS data set archive, intended to build a long term, multi-sensor data record of climate variables.

An overview of all the aforementioned aspects represent the overall thematic of this presentation.