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Multi-Platform CO data assimilation for chemistry climate interaction and air quality prediction

Carbon Monoxide (CO) plays a central role in tropospheric chemistry. As the primary sink of the
hydroxyl radical (OH), CO indirectly controls Methane (CH4) lifetime and CO is also a main
precursor of tropospheric ozone. Thus, capturing its spatio-temporal variability is important for
both short-term Air Quality monitoring and forecasting, and chemistry-climate applications.
The project aims to improve CO forecasting capabilities using the Suomi National Polar-orbiting
Partnership (SNPP) and the Joint Polar Satellite System (JPSS) Cross-track Infrared
Sounder (CrIS) within a data assimilation (DA) framework. CrIS CO retrievals products are
operationally produced by NOAA/NESDIS/STAR by means of the NOAA Unique Combined
Atmospheric Processing System (NUCAPS). The products include geophysical a priori and
quality check processing, required for DA. NUCAPS averaging kernels are available upon request
and will soon become part of the operational suite of products. The proposed work is relevant to
this solicitation in that the assimilation of NUCAPS SNPP and JPSS CrIS CO profiles will improve
CO predictability across different scales, with significant benefits for air quality forecasting and
Earth system modelling.

A 3-year reanalysis (2015 to 2017) will be performed by using several state-of-the-art DA methods
and models developed at the NOAA-ESRL, NCAR-ACOM and NOAA-STAR laboratories. This
effort aims to assess the sources of modelling uncertainties in the CO budget by analyzing different
meteorological forcings, as well as different chemistry and emissions inventories (biomass
burning, anthropogenic and chemical sources including oxidation of biogenic hydrocarbons). The
deliverables from this proposed effort are the 3-year CO emissions and four-dimensional CO
fields with fully characterized model uncertainties. This 3-year simulation will elucidate the
impacts of the 2015 El Niño wildfires on atmospheric composition, as well as the feedback of CO
to CH4 lifetime and growth rate. We will use high quality in-situ observations from aircraft and
tower measurements made in North America and the available global network to objectively
evaluate the posterior CO concentration fields and emissions fluxes.

This project addresses NOAA’s long-term goal to understand changing atmospheric composition
and its impacts. It will provide guidance for best use of the suite of satellite CO observations from
AIRS (2004) to the last JPSS-CrIS (to be launched in 2031) with regards to understanding the CO
budget and its emissions, and impact on air pollution and climate change.

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