Visualizing spatial distribution of atmospheric nitrogen dioxide by means of hyperspectral imaging

Manago, Naohiro; Takara, Yohei; Ando, Fuminori; Noro, Naoki; Irie, Hitoshi; Kuze, Hiroaki

doi:10.1364/ao.57.005970

Cited by 9 publications

(8 citation statements)

References 29 publications

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“…SO 2 camera, ∼ 1 Hz for volcanic emissions; see e.g. Mori and Burton, 2006;Bluth et al, 2007;Kern et al, 2010;Platt et al, 2018) or a tuneable BPF as a wavelength selective element (e.g. NO 2 camera, ∼ 3 min per image for stack emissions of power plants; Dekemper et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Towards imaging of atmospheric trace gases using Fabry–Pérot interferometer correlation spectroscopy in the UV and visible spectral range

et al. 2019

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Abstract. Many processes in the lower atmosphere including transport, turbulent mixing and chemical conversions happen on timescales of the order of seconds (e.g. at point sources). Remote sensing of atmospheric trace gases in the UV and visible spectral range (UV–Vis) commonly uses dispersive spectroscopy (e.g. differential optical absorption spectroscopy, DOAS). The recorded spectra allow for the direct identification, separation and quantification of narrow-band absorption of trace gases. However, these techniques are typically limited to a single viewing direction and limited by the light throughput of the spectrometer set-up. While two-dimensional imaging is possible by spatial scanning, the temporal resolution remains poor (often several minutes per image). Therefore, processes on timescales of seconds cannot be directly resolved by state-of-the-art dispersive methods. We investigate the application of Fabry–Pérot interferometers (FPIs) for the optical remote sensing of atmospheric trace gases in the UV–Vis spectral range. By choosing a FPI transmission spectrum, which is optimised to correlate with narrow-band (ideally periodic) absorption structures of the target trace gas, column densities of the trace gas can be determined with a sensitivity and selectivity comparable to dispersive spectroscopy, using only a small number of spectral channels (FPI tuning settings). Different from dispersive optical elements, the FPI can be implemented in full-frame imaging set-ups (cameras), which can reach high spatio-temporal resolution. In principle, FPI correlation spectroscopy can be applied for any trace gas with distinct absorption structures in the UV–Vis range. We present calculations for the application of FPI correlation spectroscopy to SO2, BrO and NO2 for exemplary measurement scenarios. In addition to high sensitivity and selectivity we find that the spatio temporal resolution of FPI correlation spectroscopy can be more than 2 orders of magnitude higher than state-of-the-art DOAS measurements. As proof of concept we built a 1-pixel prototype implementing the technique for SO2 in the UV. Good agreement with our calculations and conventional measurement techniques is demonstrated and no cross sensitivities to other trace gases are observed.

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Section: Introductionmentioning

confidence: 99%

Towards imaging of atmospheric trace gases using Fabry–Pérot interferometer correlation spectroscopy in the UV and visible spectral range

et al. 2019

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“…For reference, similar backgrounds were measured e.g. by Manago et al (2018) and Peters et al (2019). In order to extract the NO 2 signal attributed to the emission of GKM block 7, the anthropogenic background signal (the red line in Fig.…”

Section: Estimation Of [No 2 ]/[No X ] Ratiosmentioning

confidence: 99%

The NO<sub>2</sub> camera based on Gas Correlation Spectroscopy

Kuhn

Wagner

et al. 2021

Preprint

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Abstract. Monitoring of NO2 is in the interest of public health, because NO2 contributes to the decline of air quality in many urban regions. Its abundance can be a direct cause of asthmatic and cardiovascular diseases and plays a significant part in forming other pollutants such as ozone or particulate matter. Spectroscopic methods have proven to be reliable and of high selectivity by utilizing the characteristic spectral absorption signature of trace gasses such as NO2. However, they typically lack the spatio-temporal resolution required for real-time imaging measurements of NO2 emissions. We propose imaging measurements of NO2 in the visible spectral range using a novel instrument, an NO2 camera based on the principle of Gas Correlation Spectroscopy (GCS). For this purpose two gas cells (cuvettes) are placed in front of two camera modules. One gas cell is empty, while the other is filled with a high concentration of the target gas. The filled gas cell operates as a non-dispersive spectral filter to the incoming light, maintaining the two-dimensional imaging capability of the sensor arrays. NO2 images are generated on the basis of the signal ratio between the two images in the spectral window between 430 and 445 nm, where the NO2 absorption cross section is strongly structured. The capabilities and limits of the instrument are investigated in a numerical forward model. The predictions of this model are verified in a proof-of-concept measurement, in which the column densities in specially prepared reference cells were measured with the NO2 camera and a conventional DOAS instrument. Finally, results from measurements at a large power plant, the Großkraftwerk Mannheim (GKM), are presented. NO2 column densities of the plume emitted from a GKM chimney are quantified at a spatio-temporal resolution of 1/6 frames per second (FPS) and 0.92 m × 0.92 m. A detection limit of 1.89 · 1016 molec cm−2 was reached. An NO2 mass flux of Fm = (7.41 ± 4.23) kg h−1 was estimated on the basis of momentary wind speeds obtained from consecutive images. The camera results are verified by comparison to NO2 slant column densities obtained from elevation scans with a MAX-DOAS instrument. The instrument prototype is highly portable and cost-efficient at building costs of below 2,000 Euro.

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“…Elcoroaristizabal et al fused HSI-NIR and multivariate data analysis in a method validated by thermal-optical transmission analysis to quantify the carbon content in the atmosphere [16]. Manago et al have developed a method to observe the slant column density of NO 2 present in the atmosphere using a concise HSI camera [17]. Although the accuracy of such techniques is often high as they are nearly unsusceptible to external errors and interference, remote air pollution concentration is practically impossible to detect.…”

Section: Introductionmentioning

confidence: 99%

Air Pollution: Sensitive Detection of PM2.5 and PM10 Concentration Using Hyperspectral Imaging

et al. 2021

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This paper proposes a method to detect air pollution by applying a hyperspectral imaging algorithm for visible light, near infrared, and far infrared. By assigning hyperspectral information to images from monocular, near infrared, and thermal imaging, principal component analysis is performed on hyperspectral images taken at different times to obtain the solar radiation intensity. The Beer–Lambert law and multivariate regression analysis are used to calculate the PM2.5 and PM10 concentrations during the period, which are compared with the corresponding PM2.5 and PM10 concentrations from the Taiwan Environmental Protection Agency to evaluate the accuracy of this method. This study reveals that the accuracy in the visible light band is higher than the near-infrared and far-infrared bands, and it is also the most convenient band for data acquisition. Therefore, in the future, mobile phone cameras will be able to analyze the PM2.5 and PM10 concentrations at any given time using this algorithm by capturing images to increase the convenience and immediacy of detection.

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Visualizing spatial distribution of atmospheric nitrogen dioxide by means of hyperspectral imaging

Cited by 9 publications

References 29 publications

Towards imaging of atmospheric trace gases using Fabry–Pérot interferometer correlation spectroscopy in the UV and visible spectral range

Towards imaging of atmospheric trace gases using Fabry–Pérot interferometer correlation spectroscopy in the UV and visible spectral range

The NO<sub>2</sub> camera based on Gas Correlation Spectroscopy

Air Pollution: Sensitive Detection of PM2.5 and PM10 Concentration Using Hyperspectral Imaging

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Visualizing spatial distribution of atmospheric nitrogen dioxide by means of hyperspectral imaging

Cited by 9 publications

References 29 publications

Towards imaging of atmospheric trace gases using Fabry–Pérot interferometer correlation spectroscopy in the UV and visible spectral range

Towards imaging of atmospheric trace gases using Fabry–Pérot interferometer correlation spectroscopy in the UV and visible spectral range

The NO&lt;sub&gt;2&lt;/sub&gt; camera based on Gas Correlation Spectroscopy

Air Pollution: Sensitive Detection of PM2.5 and PM10 Concentration Using Hyperspectral Imaging

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Product

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The NO<sub>2</sub> camera based on Gas Correlation Spectroscopy