Quantitative infrared absorption cross sections of isoprene for atmospheric measurements

Brauer, Carolyn S.; Blake, Thomas A.; Sharpe, Steven W.; Sams, Robert L.; Johnson, Timothy J.

doi:10.5194/amt-7-3839-2014

Cited by 34 publications

(34 citation statements)

References 47 publications

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“…Space-based measurement of atmospheric isoprene is made challenging by its weak absorption (~0.02–0.15 K spectral signal level) and by interferences from other species active in the same spectral range. Our analysis focuses on the ν 27 and ν 28 isoprene bands (860–940 cm −1 ), since these are the strongest absorption features, and subject to the least influence from interfering atmospheric species, among its 33 reported IR spectral bands 15 between 600 and 6500 cm −1 .…”

Section: Resultsmentioning

confidence: 99%

“…These tables are calculated using the line by line radiative transfer model (LBLRTM) 46 . Spectroscopic parameters for isoprene are from Brauer et al 15 , and those for nonisoprene species relevant to this work are from the AER v3.4 line parameter database (http://rtweb.aer.com), which is based on the HIgh-resolution TRANsmission molecular absorption (HITRAN) 2012 database 47 .…”

Section: Methodsmentioning

confidence: 99%

“…Recent laboratory measurements of the isoprene cross-section in the thermal infrared (IR) 15 have provided the spectroscopic parameters needed for the remote sensing of isoprene from space. Here, we apply these spectroscopic data and demonstrate the detection of the isoprene spectral signature in space-borne radiance measurements from the Cross-track Infrared Sounder (CrIS), an imaging Fourier transform spectrometer onboard the Suomi National Polar-Orbiting Partnership (NPP) satellite.…”

Section: Introductionmentioning

confidence: 99%

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Direct retrieval of isoprene from satellite-based infrared measurements

Millet

Wells

et al. 2019

Nat Commun

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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.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Direct retrieval of isoprene from satellite-based infrared measurements

Millet

Wells

et al. 2019

Nat Commun

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“…As described in Methods, we use the CrIS-measured brightness temperature difference (Δ T b ) between the peak of the ν 28 isoprene band 20 and nearby off-peak channels (see Extended Data Fig. 1a ) as a spectral index for deriving isoprene column abundances from the satellite data.…”

Section: Isoprene Spectral Indexmentioning

confidence: 99%

Satellite isoprene retrievals constrain emissions and atmospheric oxidation

Wells

Millet

Payne

et al. 2020

Nature

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SUMMARY: Isoprene is the dominant non-methane organic compound emitted to the atmosphere 1 – 3 . It drives ozone and aerosol production, modulates atmospheric oxidation, and interacts with the global nitrogen cycle 4 – 8 . Isoprene emissions are highly uncertain 1 , 9 , as is the non-linear chemistry coupling isoprene and the hydroxyl radical, OH—its primary sink 10 – 13 . Here we present the first global isoprene measurements from space, using the Cross-track Infrared Sounder (CrIS). These isoprene measurements, together with observations of its oxidation product formaldehyde, provide new constraints on isoprene emissions and atmospheric oxidation. We find that isoprene:formaldehyde relationships measured from space are broadly consistent with current understanding of isoprene-OH chemistry, with no indication of missing OH recycling at low-NO x . We analyze these datasets over four global isoprene hotspots in relation to model predictions, and present a first demonstration of isoprene emission quantification based directly on satellite measurements of isoprene itself. A major discrepancy emerges over Amazonia, where current underestimates of natural NO x emissions bias modeled OH and hence isoprene. Over southern Africa, we find that a prominent isoprene hotspot is missing from bottom-up predictions. A multi-year analysis sheds light on interannual isoprene variability, and suggests the role of El Niño.

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“…4-5 h), and of the short lifetime of its main NMVOC precursors, most importantly isoprene, enhanced levels of HCHO are directly associated with the presence of nearby hydrocarbon emission sources. HCHO column densities retrieved from space by solar backscatter radiation in the UV-visible spectral region (Chance et al, 2000;De Smedt et al, 2008Hewson et al, 2013;De Smedt et al, 2015;González Abad et al, 2015) are used to inform about the VOC precursor fluxes in a large body of literature studies. The first studies focused on the derivation of isoprene fluxes in the US constrained by HCHO columns from GOME (Global Ozone Monitoring Instrument) or OMI (Ozone Monitoring Instrument) instruments (Palmer et al, 2003(Palmer et al, , 2006Millet et al, 2006Millet et al, , 2008.…”

Section: Introductionmentioning

confidence: 99%

How consistent are top-down hydrocarbon emissions based on formaldehyde observations from GOME-2 and OMI?

et al. 2015

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International audienceThe vertical columns of formaldehyde (HCHO) retrieved from two satellite instruments, the Global Ozone Monitoring Instrument-2 (GOME-2) on Metop-A and the Ozone Monitoring Instrument (OMI) on Aura, are used to constrain global emissions of HCHO precursors from open fires, vegetation and human activities in the year 2010. To this end, the emissions are varied and optimized using the adjoint model technique in the IMAGESv2 global CTM (chemistry-transport model) on a monthly basis and at the model resolution. Given the different local overpass times of GOME-2 (09:30 LT) and OMI (13:30 LT), the simulated diurnal cycle of HCHO columns is investigated and evaluated against ground-based optical measurements at 7 sites in Europe, China and Africa. The modelled diurnal cycle exhibits large variability, reflecting competition between photochemistry and emission variations, with noon or early afternoon maxima at remote locations (oceans) and in regions dominated by anthropogenic emissions, late afternoon or evening maxima over fire scenes, and midday minima in isoprene-rich regions. The agreement between simulated and ground-based columns is found to be generally better in summer (with a clear afternoon maximum at mid-latitude sites) than in winter, and the annually averaged ratio of afternoon to morning columns is slightly higher in the model (1.126) than in the ground-based measurements (1.043). The anthropogenic VOC (volatile organic compound) sources are found to be weakly constrained by the inversions on the global scale, mainly owing to their generally minor contribution to the HCHO columns, except over strongly polluted regions, like China. The OMI-based inversion yields total flux estimates over China close to the bottom-up inventory (24.6 vs. 25.5 in the a priori) with, however, pronounced increases in the Northeast China and reductions in the south. Lower fluxes are estimated based on GOME-2 HCHO columns (20.6 TgVOC), in particular over the Northeast, likely reflecting mismatches between the observed and the modelled diurnal cycle in this region. The resulting biogenic and pyrogenic flux estimates from both optimizations generally show a good degree of consistency. A reduction of the global annual biogenic emissions of isoprene is derived, by 9 and by 13% according to GOME-2 and OMI, respectively, compared to the a priori estimate of 363 Tg in 2010. The reduction is largest (up to 25–40%) in the Southeastern US, in accordance with earlier studies. The GOME-2 and OMI satellite columns suggest a global pyrogenic flux decrease by 36 and 33%, respectively, compared to the GFEDv3 inventory. This decrease is especially pronounced over tropical forests such as Amazonia and Thailand/Myanmar, and is supported by comparisons with IASI CO observations. In contrast to these flux reductions, the emissions due to harvest waste burning are strongly enhanced in the Northeastern China plain in June (by ca. 70% in June according to OMI) as well as over Indochina in March. Sensitivity inversions showed robustne...

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Quantitative infrared absorption cross sections of isoprene for atmospheric measurements

Cited by 34 publications

References 47 publications

Direct retrieval of isoprene from satellite-based infrared measurements

Direct retrieval of isoprene from satellite-based infrared measurements

Satellite isoprene retrievals constrain emissions and atmospheric oxidation

How consistent are top-down hydrocarbon emissions based on formaldehyde observations from GOME-2 and OMI?

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