Airborne DOAS retrievals of methane, carbon dioxide, and water vapor concentrations at high spatial resolution: application to AVIRIS-NG

Thorpe, A. K.; Frankenberg, Christian; Duren, Riley; Aubrey, A. D.; Bue, Brian D.; Green, Robert O.; Gerilowski, Konstantin; Krings, T.; Borchardt, Jakob; Kort, E. A.; Sweeney, Colm; Conley, Stephen; Roberts, Dar A.; Dennison, Philip E.

doi:10.5194/amt-10-3833-2017

Cited by 92 publications

(51 citation statements)

References 52 publications

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“…Raster flights provide precise, real‐time information on spatial patterns, while mass balance flights allow for source quantification of plumes at the facility and regional scales, after simple atmospheric modeling to convert measurement data into emission estimates (Schwietzke et al, ). Future measurement campaigns may combine in situ measurements during raster patterns with imaging spectrometry (e.g., Thorpe et al, ) on the same aircraft. This approach could combine the advantages of both measurement techniques to yield instantaneous mapping of high concentrations along with the identification and quantification of point sources.…”

Section: Measurementsmentioning

confidence: 99%

Advancing Scientific Understanding of the Global Methane Budget in Support of the Paris Agreement

Ganesan

Schwietzke²,

Poulter

et al. 2019

Global Biogeochemical Cycles

107

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The 2015 Paris Agreement of the United Nations Framework Convention on Climate Change aims to keep global average temperature increases well below 2 °C of preindustrial levels in the Year 2100. Vital to its success is achieving a decrease in the abundance of atmospheric methane (CH4), the second most important anthropogenic greenhouse gas. If this reduction is to be achieved, individual nations must make and meet reduction goals in their nationally determined contributions, with regular and independently verifiable global stock taking. Targets for the Paris Agreement have been set, and now the capability must follow to determine whether CH4 reductions are actually occurring. At present, however, there are significant limitations in the ability of scientists to quantify CH4 emissions accurately at global and national scales and to diagnose what mechanisms have altered trends in atmospheric mole fractions in the past decades. For example, in 2007, mole fractions suddenly started rising globally after a decade of almost no growth. More than a decade later, scientists are still debating the mechanisms behind this increase. This study reviews the main approaches and limitations in our current capability to diagnose the drivers of changes in atmospheric CH4 and, crucially, proposes ways to improve this capability in the coming decade. Recommendations include the following: (i) improvements to process‐based models of the main sectors of CH4 emissions—proposed developments call for the expansion of tropical wetland flux measurements, bridging remote sensing products for improved measurement of wetland area and dynamics, expanding measurements of fossil fuel emissions at the facility and regional levels, expanding country‐specific data on the composition of waste sent to landfill and the types of wastewater treatment systems implemented, characterizing and representing temporal profiles of crop growing seasons, implementing parameters related to ruminant emissions such as animal feed, and improving the detection of small fires associated with agriculture and deforestation; (ii) improvements to measurements of CH4 mole fraction and its isotopic variations—developments include greater vertical profiling at background sites, expanding networks of dense urban measurements with a greater focus on relatively poor countries, improving the precision of isotopic ratio measurements of 13CH4, CH3D, 14CH4, and clumped isotopes, creating isotopic reference materials for international‐scale development, and expanding spatial and temporal characterization of isotopic source signatures; and (iii) improvements to inverse modeling systems to derive emissions from atmospheric measurements—advances are proposed in the areas of hydroxyl radical quantification, in systematic uncertainty quantification through validation of chemical transport models, in the use of source tracers for estimating sector‐level emissions, and in the development of time and space resolved national inventories. These and other recommendations are proposed for...

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Section: Measurementsmentioning

confidence: 99%

Advancing Scientific Understanding of the Global Methane Budget in Support of the Paris Agreement

Ganesan

Schwietzke²,

Poulter

et al. 2019

Global Biogeochemical Cycles

107

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“…Posteriori -Differential Optical Absorption Spectroscopy (IMAP-DOAS) algorithm developed for AVIRIS 154 (Frankenberg et al, 2005b;Thorpe et al, 2017;Ayasse et al, 2018). DOAS retrievals isolate higher frequency features 155 resulting from gas absorption from lower frequency features that include surface reflectance as well as Rayleigh and 156…”

Section: Methane Retrieval 152mentioning

confidence: 99%

“…To retrieve the state vector from the Eetes TOA radiances, we use a forward model similar to previous IMAP-171 DOAS algorithms (Thorpe et al, 2017, Ayasse et al, 2018, with a modification to the polynomial term for surface 172 reflectance: 173 https://doi.org/10.5194/amt-2019-202 Preprint. Discussion started: 29 May 2019 c Author(s) 2019.…”

Section: Optimal Estimation 170mentioning

confidence: 99%

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Potential of next-generation imaging spectrometers to detect and quantify methane point sources from space

Jacob¹,

Cusworth²,

Varon³

et al. 2019

Preprint

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14We examine the potential for global detection of methane plumes from individual point sources with the new 15 generation of spaceborne imaging spectrometers (EnMAP, PRISMA, EMIT, SBG) scheduled for launch in 2019-2025. 16 These instruments are designed to map the Earth's surface with a sampling distance as fine as 30 ´ 30 m 2 but they have 17 spectral resolution of 7-10 nm in the 2200-2400 nm band that should also allow useful detection of atmospheric 18 methane. We simulate scenes viewed by EnMAP (10 nm spectral resolution, 180 signal-to-noise ratio) using the 19EnMAP End-to-End Simulation Tool with superimposed methane plumes generated by large-eddy simulations. We 20 retrieve atmospheric methane and surface reflectivity for these scenes using the IMAP-DOAS optimal estimation 21 algorithm. We find an EnMAP precision of 4-13% for atmospheric methane depending on surface type, allowing 22 effective single-pass detection of 100+ kg h -1 methane point sources depending on surface brightness, surface 23 homogeneity, and wind speed. Successful retrievals over very heterogeneous surfaces such as an urban mosaic require 24 finer spectral resolution. We simulated the EnMAP capability with actual plume observations over oil/gas fields in 25California from the airborne AVIRIS-NG sensor (3 ´ 3 m 2 pixel resolution, 5 nm spectral resolution, SNR 200-400). 26We spectrally and spatially downsampled AVIRIS-NG images to match EnMAP instrument specifications and found 27 that we could successfully detect point sources of ~100 kg h -1 over bright surfaces. Estimated emission rates inferred 28 with a generic Integrated Mass Enhancement (IME) method agreed within a factor of 2 between EnMAP and AVIRIS-29 NG. Better agreement may be achieved with a more customized IME method. Our results suggest that imaging 30

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“…A variety of satellite instruments for methane measurement have been launched [15]- [18]; however, the spatial resolution of these instruments (kilometers to tens of kilometers) is insufficient for studying individual point sources [19]. Airborne instruments, with a typical spatial resolution less than 10 meters, are well suited for studying individual point sources [20], [21], and the large imaging footprint provided by airborne imaging spectrometers enables the mapping of entire point source methane plumes. The Airborne Visible/Infrared Imaging Spectrometer Next Generation (AVIRIS-NG) has a demonstrated ability to detect and retrieve concentrations of methane plumes using reflected solar radiance in the shortwave infrared (SWIR; 1400-2500 nm) [22]- [24].…”

mentioning

confidence: 99%

Fast and Accurate Retrieval of Methane Concentration From Imaging Spectrometer Data Using Sparsity Prior

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Dennison

Thorpe

et al. 2020

IEEE Trans. Geosci. Remote Sensing

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The strong radiative forcing by atmospheric methane has stimulated interest in identifying natural and anthropogenic sources of this potent greenhouse gas. Point sources are important targets for quantification, and anthropogenic targets have potential for emissions reduction. Methane point source plume detection and concentration retrieval have been previously demonstrated using data from the Airborne Visible InfraRed Imaging Spectrometer Next Generation (AVIRIS-NG). Current quantitative methods have tradeoffs between computational requirements and retrieval accuracy, creating obstacles for processing real-time data or large datasets from flight campaigns. We present a new computationally efficient algorithm that applies sparsity and an albedo correction to matched filter retrieval of trace gas concentration-pathlength. The new algorithm was tested using AVIRIS-NG data acquired over several point source plumes in Ahmedabad, India. The algorithm was validated using simulated AVIRIS-NG data including synthetic plumes of known methane concentration. Sparsity and albedo correction together reduced the root mean squared error of retrieved methane concentration-pathlength enhancement by 60.7% compared with a previous robust matched filter method. Background noise was reduced by a factor of 2.64. The new algorithm was able to process the entire 300 flightline 2016 AVIRIS-NG India campaign in just over 8 hours on a desktop computer with GPU acceleration.

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Airborne DOAS retrievals of methane, carbon dioxide, and water vapor concentrations at high spatial resolution: application to AVIRIS-NG

Cited by 92 publications

References 52 publications

Advancing Scientific Understanding of the Global Methane Budget in Support of the Paris Agreement

Advancing Scientific Understanding of the Global Methane Budget in Support of the Paris Agreement

Potential of next-generation imaging spectrometers to detect and quantify methane point sources from space

Fast and Accurate Retrieval of Methane Concentration From Imaging Spectrometer Data Using Sparsity Prior

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