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

2016 ◽  
Author(s):  
Kam W. 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 four-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 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 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 Near-infrared remote sensing of Los Angeles trace gas distributions from a mountaintop site

2013 ◽  
Vol 6 (5) ◽  
pp. 8807-8854
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 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.

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>

scholarly journals Impacts of the 2020 COVID-19 Shutdown Measures on Ozone Production in the Los Angeles Basin

2020 ◽  
Author(s):  
Cesunica Ivey ◽  
Ziqi Gao ◽  
Khanh Do ◽  
Arash Kashfi Yeganeh ◽  
Armistead Russell ◽  
...  
Keyword(s):  
Los Angeles ◽  
Ozone Concentration ◽  
South Coast ◽  
Pollutant Emissions ◽  
Ozone Production ◽  
The South ◽  
Los Angeles Basin ◽  
Time Period ◽  
South Coast Air Basin ◽  
The Impact

In March and April 2020, the South Coast Air Basin of California (USA) experienced noticeable declines in on-road activity and primary traffic-related pollutant emissions. However, secondary ozone concentration trends were not consistent across the basin. This research letter explores the impact of meteorology and emissions during this time period. The study elucidates the potential impacts on ozone nonattainment status for the region.

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