Urban-focused satellite CO2 observations from the Orbiting Carbon Observatory-3: A first look at the Los Angeles megacity

Matthäus Kiel (1) , Annmarie Eldering (1) , Dustin D. Roten (2) , John C. Lin (2) , Sha Feng (3) , Ruixue Lei (3) , Thomas Lauvaux (4, 5) , Tomohiro Oda (6, 7, 8) , Coleen M. Roehl (9) , Jean-Francois Blavier (1) , Laura T. Iraci (10)

1 JPL - Jet Propulsion Laboratory
2 Department of Atmospheric Sciences [Salt Lake City]
3 Department of Meteorology and Atmospheric Science [PennState]
4 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
5 SATINV - Modélisation INVerse pour les mesures atmosphériques et SATellitaires
6 GSFC - NASA Goddard Space Flight Center
7 USRA - Universities Space Research Association [Washington]
8 University of Maryland [College Park]
9 Division of Geological and Planetary Sciences [Pasadena]
10 Atmospheric Chemistry and Dynamics Branch [Moffett Field]

NASA's Orbiting Carbon Observatory-3 (OCO-3) was designed to support the quantification and monitoring of anthropogenic CO 2 emissions. Its Snapshot Area Map (SAM) and target mode measurements provide an innovative dataset for carbon studies on sub-city scales. Unlike any other current space-based instrument, OCO-3 has the ability to scan large contiguous areas of emission hot spots like cities, power plants, and volcanoes. These measurements result in dense, fine-scale spatial maps of column averaged dry-air mole fractions of carbon dioxide (X CO 2). For the first time, we present and analyze X CO 2 distributions over the Los Angeles megacity (LA) derived from OCO-3 SAM and target mode observations. Urban X CO 2 enhancements range from 0 − 6 ppm (median enhancements ≃ 2 ppm) relative to a clean background and show excellent agreement with nearby ground-based TCCON measurements of X CO 2. OCO-3's dense observations reveal intra-urban variations of X CO 2 over the city that have never been observed from space before. The spatial variations are mainly driven by the complex fossil fuel emission patterns and meteorological conditions in the LA Basin and are in good agreement with those from co-located TROPOMI measurements of co-emitted NO 2. Differences between measured and simulated X CO 2 enhancements from two models (WRF-Chem and X-STILT) are typically below 1 ppm with larger differences for some sub regions. Both models capture the observed intra-urban X CO 2 gradients. Further, OCO-3's multi-swath measurements capture about three times as much of the city emissions compared to single-swath overpasses. OCO-3's frequent target and SAM mode observations will pave the way to constrain urban emissions at finer, sub-city scales.

Domaines: Planète et Univers [physics]

Matthäus Kiel, Annmarie Eldering, Dustin D. Roten, John C. Lin, Sha Feng, et al.. Urban-focused satellite CO2 observations from the Orbiting Carbon Observatory-3: A first look at the Los Angeles megacity. Remote Sensing of Environment, 2021, 258, pp.112314. ⟨10.1016/j.rse.2021.112314⟩. ⟨insu-03231646⟩