1995 Fisher Scientific Award Lecture Reflections of an atmospheric chemist wondering why he won an analytical chemistry award

1996 ◽  
Vol 74 (10) ◽  
pp. 1765-1773
Author(s):  
H.I. Schiff
Keyword(s):  
Remote Sensing ◽  
Los Angeles ◽  
Near Infrared ◽  
Laser Diodes ◽  
Grand Canyon ◽  
Ambient Air ◽  
Tunable Diode Laser ◽  
Lead Salt ◽  
Fast Time ◽  
Atmospheric Measurements

The author recalls his scientific career starting with electrochemistry and gas phase kinetics and leading, largely by serendipity, to atmospheric chemistry and measurements in the atmosphere using rockets and stratospheric balloons. The scientific problems met along the way required measurements with instruments that were not commercially available and required development of new methods and techniques. These included mass spectrometry, chemiluminescence, and tunable Diode Laser Absorption Spectrometry (TDLAS) to measure trace concentrations of gases in the lower and upper atmosphere. TDLAS is considered to be the method of choice where freedom from interferences, high sensitivity, and fast time response are required. Lead salt laser diodes operate in the near infrared where most molecules of atmospheric interest have strong fundamental absorptions. The research groups at York University and at Unisearch Associates have been pioneers in applying this powerful technique to atmospheric measurements in a variety of environments including the pristine air over the Pacific, at the top of Mauna Loa, at the Grand Canyon, and the polluted air of Los Angeles and other major cities. The results of recent measurements of the emissions of two strong greenhouse gases, CF4 and C2F6, from Quebec aluminium refineries are described. More recently a family of instruments based on near-infrared laser diodes have been developed that can make remote-sensing measurements of a number of pollutants in ambient air and industrial stacks. Examples of passive, on-road, remote-sensing measurements of automobile exhaust emissions of CO and CO2, and of in-stack emissions of HF are presented. Another remote-sensing instrument that has been developed is an improved visible and UV Differential Optical Absorption Spectrometer (DOAS) capable of measuring, remotely and simultaneously, a number of important pollutants. Examples of measurements of NO, NO2, O3, benzene, and toluene are presented. Key words: air measurements, instruments, remote sensing.

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 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

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.

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.

Estimating nitrous oxide (N2O) emissions for the Los Angeles Megacity using mountaintop remote sensing observations

2021 ◽  
Vol 259 ◽  
pp. 112351
Author(s):  
Olivia Addington ◽  
Zhao-Cheng Zeng ◽  
Thomas Pongetti ◽  
Run-Lie Shia ◽  
Kevin R. Gurney ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Nitrous Oxide ◽  
Los Angeles ◽  
N2o Emissions

scholarly journals A Modified Bare Soil Index to Identify Bare Land Features during Agricultural Fallow-Period in Southeast Asia Using Landsat 8

Land ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 231
Author(s):  
Can Trong Nguyen ◽  
Amnat Chidthaisong ◽  
Phan Kieu Diem ◽  
Lian-Zhi Huo
Keyword(s):  
Remote Sensing ◽  
Land Cover ◽  
Urban Areas ◽  
Near Infrared ◽  
Urban Landscape ◽  
Bare Soil ◽  
Critical Element ◽  
Landsat 8 ◽  
Climate Conditions ◽  
Fallow Period

Bare soil is a critical element in the urban landscape and plays an essential role in urban environments. Yet, the separation of bare soil and other land cover types using remote sensing techniques remains a significant challenge. There are several remote sensing-based spectral indices for barren detection, but their effectiveness varies depending on land cover patterns and climate conditions. Within this research, we introduced a modified bare soil index (MBI) using shortwave infrared (SWIR) and near-infrared (NIR) wavelengths derived from Landsat 8 (OLI—Operational Land Imager). The proposed bare soil index was tested in two different bare soil patterns in Thailand and Vietnam, where there are large areas of bare soil during the agricultural fallow period, obstructing the separation between bare soil and urban areas. Bare soil extracted from the MBI achieved higher overall accuracy of about 98% and a kappa coefficient over 0.96, compared to bare soil index (BSI), normalized different bare soil index (NDBaI), and dry bare soil index (DBSI). The results also revealed that MBI considerably contributes to the accuracy of land cover classification. We suggest using the MBI for bare soil detection in tropical climatic regions.

Laser therapy applications for osteoarthritis and chronic joint pain – A randomized placebo-controlled clinical trial

2012 ◽  
Vol 1 (4) ◽  
Author(s):  
Nelson Marquina ◽  
Roger Dumoulin-White ◽  
Arkady Mandel ◽  
Lothar Lilge
Keyword(s):  
Clinical Trial ◽  
Near Infrared ◽  
Continuous Wave ◽  
Laser System ◽  
Laser Diodes ◽  
Average Power ◽  
Evaluation Criteria ◽  
Adjunctive Treatment ◽  
Controlled Clinical Trial ◽  
Primary Evaluation

AbstractA randomized placebo-controlled clinical trial to evaluate an adjunctive treatment modality for pain associated with knee disorders was conducted utilizing a therapeutic laser system (low energy, non-surgical).The therapeutic laser system utilized a dual wavelength, multiple diode laser cluster probe with five super-pulsed 905 nm near-infrared (NIR) laser diodes, each emitting at 40 mW average power and four continuous wave 660 nm visible (VIS) red laser diodes, each emitting at 25 mW. It was used as an adjunctive modality providing 12 treatments, three times a week to a homogeneous patient population (n=126), in combination with standardized chiropractic techniques, to evaluate effectiveness on subjects presenting with osteoarthritis and knee pain. The primary endpoint was measured by the visual analog scale (VAS) to assess pain levels on a scale of 0–10. The success criteria for an individual patient in this study were identified as an improvement of 30% or more in the VAS from baseline to 12th treatment and/or an improvement of 20% or more in the VAS from baseline to 30-day follow-up evaluation.The data obtained in the study demonstrated that the present therapeutic laser system provided significant pain relief and osteoarthritic improvements in all primary evaluation criteria, with a statistical and clinical significance of

scholarly journals Lidar measurement of snow depth: a review

2013 ◽  
Vol 59 (215) ◽  
pp. 467-479 ◽  
Author(s):  
Jeffrey S. Deems ◽  
Thomas H. Painter ◽  
David C. Finnegan
Keyword(s):  
Remote Sensing ◽  
Snow Depth ◽  
Near Infrared ◽  
Ground Surface ◽  
Lidar Measurement ◽  
Snow Hydrology ◽  
Sensing Technology ◽  
Transfer Error ◽  
Scale Range ◽  
Visible Wavelengths

AbstractLaser altimetry (lidar) is a remote-sensing technology that holds tremendous promise for mapping snow depth in snow hydrology and avalanche applications. Recently lidar has seen a dramatic widening of applications in the natural sciences, resulting in technological improvements and an increase in the availability of both airborne and ground-based sensors. Modern sensors allow mapping of vegetation heights and snow or ground surface elevations below forest canopies. Typical vertical accuracies for airborne datasets are decimeter-scale with order 1 m point spacings. Ground-based systems typically provide millimeter-scale range accuracy and sub-meter point spacing over 1 m to several kilometers. Many system parameters, such as scan angle, pulse rate and shot geometry relative to terrain gradients, require specification to achieve specific point coverage densities in forested and/or complex terrain. Additionally, snow has a significant volumetric scattering component, requiring different considerations for error estimation than for other Earth surface materials. We use published estimates of light penetration depth by wavelength to estimate radiative transfer error contributions. This paper presents a review of lidar mapping procedures and error sources, potential errors unique to snow surface remote sensing in the near-infrared and visible wavelengths, and recommendations for projects using lidar for snow-depth mapping.

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