Toward CO2 and CH4 measurements by ground-based observations of surface-scattered sunlight

2021 ◽  
Author(s):  
Benedikt Hemmer ◽  
Christin Proß ◽  
Stanley P. Sander ◽  
Thomas J. Pongetti ◽  
Zhao-Cheng Zeng ◽  
...  
Keyword(s):  
Los Angeles ◽  
Urban Areas ◽  
Near Infrared ◽  
Chem Phys ◽  
Retrieval Algorithm ◽  
Los Angeles Basin ◽  
Satellite Measurements ◽  
Precise Knowledge ◽  
Extended Sources

<div> <div>Precise knowledge of sources and sinks in the carbon cycle is desired to understand its sensitivity to climate change and to account and verify man-made emissions. In this context, extended sources like urban areas play an important role. While in-situ measurements of carbon dioxide (CO<sub>2</sub>) and methane (CH<sub>4</sub>) are highly accurate but localized, satellites measure column-integrated concentrations over an extended footprint. The CLARS-FTS [1, 2] stationed at the Mt. Wilson observatory looking downward into the Los Angeles basin has pioneered an innovative measurement technique that fills the sensitivity gap between in-situ and satellite measurements. The technique enables mapping the urban greenhouse gas concentration fields by collecting spectra of ground scattered sunlight and scanning through the region.</div> <div> </div> <div>Here, we report on progress developing a portable setup for a CLARS-FTS-like measurement geometry. The instrument is based on the EM27/SUN FTS with a modified pointing technique and a more sensitive detector. The retrieval algorithm is based on the RemoTeC software, previously employed for solar backscatter satellite measurements. We discuss first steps in terms of instrument performance and retrieval exercises. For the latter, we have carried out simulations on how the neglect of scattering by the retrieval affects the retrieved boundary layer concentrations of CO<sub>2</sub> and CH<sub>4</sub> for an ensemble of hypothetical scenes with variable complexity in aeorsol loadings and viewing geometry. We also report on a test to apply RemoTeC to a small set of CLARS-FTS spectra collected throughout the Los Angeles basin.</div> <div> </div> <div><em>References</em></div> <div>[1] Fu, D. et al., 2014: Near-infrared remote sensing of Los Angeles trace gas distributions from a mountaintop site, Atmos. Meas. Tech., 7, 713–729, https://doi.org/10.5194/amt-7-713-2014</div> [2] Wong, K. W. et al., 2015: Mapping CH4 : CO2 ratios in Los Angeles with CLARS-FTS from Mount Wilson, California, Atmos. Chem. Phys., 15, 241–252, https://doi.org/10.5194/acp-15-241-2015</div>

Toward CO2 and CH4 measurements by ground based observations of surface-scattered sunlight: Radiative transfer modeling

2020 ◽  
Author(s):  
Christin Proß ◽  
Benedikt Hemmer ◽  
Constanze Wellmann ◽  
Julian Kostinek ◽  
André Butz
Keyword(s):  
Radiative Transfer ◽  
Urban Areas ◽  
Scattered Light ◽  
Simultaneous Estimation ◽  
Atmospheric Scattering ◽  
Precise Knowledge ◽  
First Results ◽  
Extended Sources ◽  
Retrieval Software

<p>Precise knowledge of sources and sinks in the carbon cycle is desired to understand<br>its sensitivity to climate change and to account and verify man-made emissions. An<br>important role herein play extended sources like urban areas. While in-situ measure-<br>ments of carbon dioxide (CO<sub>2</sub>) and methane (CH<sub>4</sub>) are highly accurate but localized,<br>satellites measure column-integrated concentrations over an extended footprint. Our<br>innovative measurement technique aims at determining CO<sub>2</sub> and CH<sub>4</sub> concentrations<br>near to the ground on the scale of a few kilometers and therefore fills the sensitivity<br>gap between in-situ and satellite measurements.<br>Using a modified EM27/SUN Fourier transform spectrometer we are able to record<br>spectra of surface scattered sunlight in the range of 4000 − 11000 cm<sup>−1</sup> . To accurately<br>retrieve CO<sub>2</sub> and CH<sub>4</sub> concentrations an advanced retrieval method is required that<br>includes the simultaneous estimation of atmospheric scattering properties.<br>Based on our radiative transfer and retrieval software RemoTeC, we built a simulation<br>environment that includes atmospheric scattering processes. With this tool we can<br>generate and retrieve synthetic scattered light observations. Here we present our<br>simulation environment, first results and ongoing developments.</p>

scholarly journals Differential Column Measurements Using Compact Solar-Tracking Spectrometers

2016 ◽  
Author(s):  
Jia Chen ◽  
Camille Viatte ◽  
Jacob K. Hedelius ◽  
Taylor Jones ◽  
Jonathan E. Franklin ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Los Angeles ◽  
Urban Areas ◽  
Integration Time ◽  
Small Scale ◽  
Los Angeles Basin ◽  
Solar Tracking ◽  
Regional Sources ◽  
New Applications ◽  
Atmospheric Phenomena

Abstract. We demonstrate the use of compact solar-tracking Fourier transform spectrometers (Bruker EM27/SUN) for differential measurements of the column-averaged dry-air mole fractions of CH4 and CO2 within urban areas. Using Allan variance analysis, we show that the differential column measurement has a precision of 0.1 ‰ for XCO2 and XCH4 using an optimum integration time of 10 min, which corresponds to standard deviations of 0.04 ppm, and 0.2 ppb, respectively. The sensor system is very stable over time and after relocation across the continent. We report tests of the differential column measurement, and its sensitivity to emission sources, by measuring the downwind minus upwind column gradient ΔXCH4 across dairy farms in the Chino California area and using the data to verify emissions reported in the literature. Spatial column gradient ratios ΔXCH4/ΔXCO2 were observed across Pasadena within the Los Angeles basin, indicating values consistent with regional emission ratios from the literature. Our precise, rapid measurements allow us to determine significant short-term variations (5–10 minutes) of ΔXCO2 and ΔXCH4, and to show that they represent atmospheric phenomena. Overall, this study helps establish a range of new applications for compact solar-viewing Fourier transform spectrometers. By accurately measuring the small differences in integrated column amounts across local and regional sources, we directly observe the mass loading of the atmosphere due to the influence of emissions in the intervening locale. The inference of the source strength is much more direct than inversion modeling using only surface concentrations, and less subject to errors associated with small-scale transport phenomena.

scholarly journals Diurnal tracking of anthropogenic CO<sub>2</sub> emissions in the Los Angeles basin megacity during spring 2010

2013 ◽  
Vol 13 (8) ◽  
pp. 4359-4372 ◽  
Author(s):  
S. Newman ◽  
S. Jeong ◽  
M. L. Fischer ◽  
X. Xu ◽  
C. L. Haman ◽  
...  
Keyword(s):  
Los Angeles ◽  
Transport Model ◽  
Weather Research And Forecasting ◽  
Los Angeles Basin ◽  
Boundary Layer Height ◽  
Anthropogenic Component ◽  
Model Predictions ◽  
Stochastic Time ◽  
Total Column

Abstract. Attributing observed CO2 variations to human or natural cause is critical to deducing and tracking emissions from observations. We have used in situ CO2, CO, and planetary boundary layer height (PBLH) measurements recorded during the CalNex-LA (CARB et al., 2008) ground campaign of 15 May–15 June 2010, in Pasadena, CA, to deduce the diurnally varying anthropogenic component of observed CO2 in the megacity of Los Angeles (LA). This affordable and simple technique, validated by carbon isotope observations and WRF-STILT (Weather Research and Forecasting model – Stochastic Time-Inverted Lagrangian Transport model) predictions, is shown to robustly attribute observed CO2 variation to anthropogenic or biogenic origin over the entire diurnal cycle. During CalNex-LA, local fossil fuel combustion contributed up to ~50% of the observed CO2 enhancement overnight, and ~100% of the enhancement near midday. This suggests that sufficiently accurate total column CO2 observations recorded near midday, such as those from the GOSAT or OCO-2 satellites, can potentially be used to track anthropogenic emissions from the LA megacity.

scholarly journals Diurnal tracking of anthropogenic CO<sub>2</sub> emissions in the Los Angeles basin megacity during spring, 2010

2012 ◽  
Vol 12 (2) ◽  
pp. 5771-5801 ◽  
Author(s):  
S. Newman ◽  
S. Jeong ◽  
M. L. Fischer ◽  
X. Xu ◽  
C. L. Haman ◽  
...  
Keyword(s):  
Los Angeles ◽  
Fossil Fuel ◽  
Simple Technique ◽  
Anthropogenic Emissions ◽  
Fossil Fuel Combustion ◽  
Planetary Boundary Layer Height ◽  
Los Angeles Basin ◽  
Boundary Layer Height ◽  
Anthropogenic Component

Abstract. Attributing observed CO2 variations to human or natural cause is critical to deducing and tracking emissions from observations. We have used in situ CO2, CO, and planetary boundary layer height (PBLH) measurements recorded during the CalNex-LA (CARB et al., 2008) ground campaign of 15 May–15 June 2010, in Pasadena, CA, to deduce the diurnally varying anthropogenic component of observed CO2 in the megacity of Los Angeles (LA). This affordable and simple technique, validated by carbon isotope observations, is shown to robustly attribute observed CO2 variation to anthropogenic or biogenic origin. During CalNex-LA, local fossil fuel combustion contributed up to ~50 % of the observed CO2 enhancement overnight, and ~100 % during midday. This suggests midday column observations over LA, such as those made by satellites relying on reflected sunlight, can be used to track anthropogenic emissions.

scholarly journals Near-infrared remote sensing of Los Angeles trace gas distributions from a mountaintop site

2014 ◽  
Vol 7 (3) ◽  
pp. 713-729 ◽  
Author(s):  
D. Fu ◽  
T. J. Pongetti ◽  
J.-F. L. Blavier ◽  
T. J. Crawford ◽  
K. S. Manatt ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Los Angeles ◽  
Greenhouse Gases ◽  
Near Infrared ◽  
Global Climate ◽  
Ghg Emissions ◽  
Anthropogenic Source ◽  
Los Angeles Basin ◽  
Remote Sensing Technique ◽  
Novel Approach

Abstract. The Los Angeles basin is a significant anthropogenic source of major greenhouse gases (CO2 and CH4) and the pollutant CO, contributing significantly to regional and global climate change. We present a novel approach for monitoring the spatial and temporal distributions of greenhouse gases in the Los Angeles basin using a high-resolution spectroscopic remote sensing technique. A new Fourier transform spectrometer called CLARS-FTS has been deployed since May, 2010, at Jet Propulsion Laboratory (JPL)'s California Laboratory for Atmospheric Remote Sensing (CLARS) on Mt. Wilson, California, for automated long-term measurements of greenhouse gases. The instrument design and performance of CLARS-FTS are presented. From its mountaintop location at an altitude of 1673 m, the instrument points at a programmed sequence of ground target locations in the Los Angeles basin, recording spectra of reflected near-IR solar radiation. Column-averaged dry-air mole fractions of greenhouse gases (XGHG) including XCO2, XCH4, and XCO are retrieved several times per day for each target. Spectra from a local Spectralon® scattering plate are also recorded to determine background (free tropospheric) column abundances above the site. Comparisons between measurements from LA basin targets and the Spectralon® plate provide estimates of the boundary layer partial column abundances of the measured species. Algorithms are described for transforming the measured interferograms into spectra, and for deriving column abundances from the spectra along with estimates of the measurement precision and accuracy. The CLARS GHG measurements provide a means to infer relative, and possibly absolute, GHG emissions.

scholarly journals The Total Carbon Column Observing Network

2011 ◽  
Vol 369 (1943) ◽  
pp. 2087-2112 ◽  
Author(s):  
Debra Wunch ◽  
Geoffrey C. Toon ◽  
Jean-François L. Blavier ◽  
Rebecca A. Washenfelder ◽  
Justus Notholt ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Near Infrared ◽  
Total Carbon ◽  
Global Network ◽  
Satellite Measurements ◽  
Accuracy And Precision ◽  
Science Investigations ◽  
Total Column ◽  
Better Than

A global network of ground-based Fourier transform spectrometers has been founded to remotely measure column abundances of CO 2 , CO, CH 4 , N 2 O and other molecules that absorb in the near-infrared. These measurements are directly comparable with the near-infrared total column measurements from space-based instruments. With stringent requirements on the instrumentation, acquisition procedures, data processing and calibration, the Total Carbon Column Observing Network (TCCON) achieves an accuracy and precision in total column measurements that is unprecedented for remote-sensing observations (better than 0.25% for CO 2 ). This has enabled carbon-cycle science investigations using the TCCON dataset, and allows the TCCON to provide a link between satellite measurements and the extensive ground-based in situ network.

scholarly journals Emission factor ratios, SOA mass yields, and the impact of vehicular emissions on SOA formation

2014 ◽  
Vol 14 (5) ◽  
pp. 2383-2397 ◽  
Author(s):  
J. J. Ensberg ◽  
P. L. Hayes ◽  
J. L. Jimenez ◽  
J. B. Gilman ◽  
W. C. Kuster ◽  
...  
Keyword(s):  
Los Angeles ◽  
Urban Areas ◽  
Organic Aerosol ◽  
Vehicular Emissions ◽  
Los Angeles Basin ◽  
Relative Contribution ◽  
Chamber Studies ◽  
Using Data ◽  
Factor Ratios ◽  
The Impact

Abstract. The underprediction of ambient secondary organic aerosol (SOA) levels by current atmospheric models in urban areas is well established, yet the cause of this underprediction remains elusive. Likewise, the relative contribution of emissions from gasoline- and diesel-fueled vehicles to the formation of SOA is generally unresolved. We investigate the source of these two discrepancies using data from the 2010 CalNex experiment carried out in the Los Angeles Basin (Ryerson et al., 2013). Specifically, we use gas-phase organic mass (GPOM) and CO emission factors in conjunction with measured enhancements in oxygenated organic aerosol (OOA) relative to CO to quantify the significant lack of closure between expected and observed organic aerosol concentrations attributable to fossil-fuel emissions. Two possible conclusions emerge from the analysis to yield consistency with the ambient data: (1) vehicular emissions are not a dominant source of anthropogenic fossil SOA in the Los Angeles Basin, or (2) the ambient SOA mass yields used to determine the SOA formation potential of vehicular emissions are substantially higher than those derived from laboratory chamber studies.

scholarly journals KLUM: An Urban VNIR and SWIR Spectral Library Consisting of Building Materials

2019 ◽  
Vol 11 (18) ◽  
pp. 2149
Author(s):  
Rebecca Ilehag ◽  
Andreas Schenk ◽  
Yilin Huang ◽  
Stefan Hinz
Keyword(s):  
Remote Sensing ◽  
Urban Areas ◽  
Building Materials ◽  
Near Infrared ◽  
Imaging Spectroscopy ◽  
Short Wave ◽  
Spectral Library ◽  
Spectral Libraries ◽  
Roofing Materials

Knowledge about the existing materials in urban areas has, in recent times, increased in importance. With the use of imaging spectroscopy and hyperspectral remote sensing techniques, it is possible to measure and collect the spectra of urban materials. Most spectral libraries consist of either spectra acquired indoors in a controlled lab environment or of spectra from afar using airborne systems accompanied with in situ measurements. Furthermore, most publicly available spectral libraries have, so far, not focused on facade materials but on roofing materials, roads, and pavements. In this study, we present an urban spectral library consisting of collected in situ material spectra with imaging spectroscopy techniques in the visible and near-infrared (VNIR) and short-wave infrared (SWIR) spectral range, with particular focus on facade materials and material variation. The spectral library consists of building materials, such as facade and roofing materials, in addition to surrounding ground material, but with a focus on facades. This novelty is beneficial to the community as there is a shift to oblique-viewed Unmanned Aerial Vehicle (UAV)-based remote sensing and thus, there is a need for new types of spectral libraries. The post-processing consists partly of an intra-set solar irradiance correction and recalculation of reference spectra caused by signal clipping. Furthermore, the clustering of the acquired spectra was performed and evaluated using spectral measures, including Spectral Angle and a modified Spectral Gradient Angle. To confirm and compare the material classes, we used samples from publicly available spectral libraries. The final material classification scheme is based on a hierarchy with subclasses, which enables a spectral library with a larger material variation and offers the possibility to perform a more refined material analysis. The analysis reveals that the color and the surface structure, texture or coating of a material plays a significantly larger role than what has been presented so far. The samples and their corresponding detailed metadata can be found in the Karlsruhe Library of Urban Materials (KLUM) archive.

scholarly journals Monthly trends of methane emissions in Los Angeles from 2011 to 2015 inferred by CLARS-FTS observations

2016 ◽  
Vol 16 (20) ◽  
pp. 13121-13130 ◽  
Author(s):  
Clare K. Wong ◽  
Thomas J. Pongetti ◽  
Tom Oda ◽  
Preeti Rao ◽  
Kevin R. Gurney ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Los Angeles ◽  
Near Infrared ◽  
Late Summer ◽  
Methane Emissions ◽  
Los Angeles Basin ◽  
Top Down ◽  
Time Period ◽  
Infrared Remote Sensing ◽  
Early Fall

Abstract. This paper presents an analysis of methane emissions from the Los Angeles Basin at monthly timescales across a 4-year time period – from September 2011 to August 2015. Using observations acquired by a ground-based near-infrared remote sensing instrument on Mount Wilson, California, combined with atmospheric CH4–CO2 tracer–tracer correlations, we observed −18 to +22 % monthly variability in CH4 : CO2 from the annual mean in the Los Angeles Basin. Top-down estimates of methane emissions for the basin also exhibit significant monthly variability (−19 to +31 % from annual mean and a maximum month-to-month change of 47 %). During this period, methane emissions consistently peaked in the late summer/early fall and winter. The estimated annual methane emissions did not show a statistically significant trend over the 2011 to 2015 time period.

scholarly journals Emission factor ratios, SOA mass yields, and the impact of vehicular emissions on SOA formation

2013 ◽  
Vol 13 (10) ◽  
pp. 27779-27810 ◽  
Author(s):  
J. J. Ensberg ◽  
P. L. Hayes ◽  
J. L. Jimenez ◽  
J. B. Gilman ◽  
W. C. Kuster ◽  
...  
Keyword(s):  
Los Angeles ◽  
Urban Areas ◽  
Organic Aerosol ◽  
Diesel Emissions ◽  
Vehicular Emissions ◽  
Aerosol Formation ◽  
Los Angeles Basin ◽  
Relative Contribution ◽  
Chamber Studies ◽  
The Impact

Abstract. The underprediction of ambient secondary organic aerosol (SOA) levels by atmospheric models in urban areas is well established, yet the cause of this underprediction remains elusive. Likewise, the relative contribution of emissions from gasoline- and diesel-fueled vehicles to the formation of SOA is generally unresolved. Here we address these two issues using data from the 2010 CalNex experiment carried out in the Los Angeles basin (Ryerson et al., 2013). We use gas-phase organic mass (GPOM) and CO emission factors in conjunction with measured enhancements in oxygenated organic aerosol (OOA) relative to CO to investigate the relative importance of gasoline vs. diesel emissions to organic aerosol formation. Two possible conclusions emerge from the analysis to yield consistency with the ambient data: (1) vehicular emissions are not a dominant source of anthropogenic fossil SOA in the Los Angeles basin, or (2) ambient SOA mass yields are substantially higher than those derived from laboratory chamber studies.

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