Isoprene is the atmosphere’s most important non-methane organic compound, with key impacts on atmospheric oxidation, ozone, and organic aerosols. In-situ isoprene measurements are sparse, and satellite-based constraints have employed an indirect approach using its oxidation product formaldehyde, which is affected by non-isoprene sources plus uncertainty and spatial smearing in the isoprene-formaldehyde relationship. Direct global isoprene measurements are therefore needed to better understand its sources, sinks, and atmospheric impacts. Here we show that the isoprene spectral signatures are detectable from space using the satellite-borne Cross-track Infrared Sounder (CrIS), develop a full-physics retrieval methodology for quantifying isoprene abundances from these spectral features, and apply the algorithm to CrIS measurements over Amazonia. The results are consistent with model output and in-situ data, and establish the feasibility of direct global space-based isoprene measurements. Finally, we demonstrate the potential for combining space-based measurements of isoprene and formaldehyde to constrain atmospheric oxidation over isoprene source regions.
Bibliographical noteFunding Information:
This work was supported by the NASA Atmospheric Composition: Aura Science Team and Atmospheric Composition Modeling and Analysis Program (Grants #NNN13D455T and #NNX17AF61G), and by the Jet Propulsion Laboratory Spontaneous Research and Technology Development program. The authors thank Aldona Wiacek, Barry L. Lefer, Carolyn S. Brauer, Chris Barnet, Helen M. Worden, Iouli Gordon, John R. Worden, Jessica L. Neu, Kaley A. Walker, Kevin W. Bowman, Michael Garay, Monika Kopacz, Nathaniel J. Livesey, Olga Kalashnikova, Richard S. Eckman, and Trissevgeni Stavrakou for many helpful discussions. We are grateful to Keeyoon Sung, Brian J. Drouin, and Timothy J. Crawford for providing laboratory evaluation of the isoprene spectroscopic parameters and to Matthew Alvarado, Karen Cady-Pereira, Jennifer Hegarty, and Irina Strickland for generating and testing isoprene absorption look-up tables for use within the algorithm. We acknowledge John Shilling and the GoAmazon G1 aircraft team supported by the U.S. Department of Energy Office of Science, the Central Office of the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA), the Instituto Nacional de Pesquisas da Amazonia (INPA), and the Instituto Nacional de Pesquisas Espaciais (INPE) for the GoAmazon measurements. Part of the research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. © 2019. All rights reserved.
PubMed: MeSH publication types
- Journal Article