AS3.20
Orals: Fri, 28 Apr | Room 0.51
We have developed a turnkey, fast response two-channel NOx monitor (NOx =NO + NO2) which provides simultaneous measurements of both NOx and NO2 and thus NO by subtraction. The NOx channel employs a carefully controlled concentration of photolytically-produced ozone (O3) to convert NO into NO2. The monitor can measure NO2 and NOx with an accuracy of better than 5% and precision of < 0.2 ppb (1s, 1s) with <1 second physical time constant in each measurement channel. The monitor is based on Aerodyne Research’s patented CAPS (Cavity Attenuated Phase Shift) technology previously employed to measure NO2concentrations, aerosol optical extinction and aerosol single scattering albedo.
A CAPS-based NO2 monitor utilizes a light-emitting diode (LED) as a light source (450 nm for the NO2 channel and 405 nm for the total NOx channel) and a sample cell incorporating two high reflectivity mirrors; a vacuum photodiode is used to detect the light emitted from the cell. The square wave modulated light from the LED passes through the absorption cell and is detected as a distorted waveform which is characterized by a phase shift with respect to the initial modulation. The amount of that phase shift is a function of fixed instrument properties - cell length, mirror reflectivity, and modulation frequency– and of the presence of variable concentrations of nitrogen dioxide. The mixing ratio is calculated from the value of the cotangent of the phase shift, the speed of light, LED modulation frequency and the absorption coefficient of NO2. The use of 405 nm detection in the total NOx channel greatly reduces the possible interference caused by the presence of several ppm of O3 in the sample flow.
We present data from an intercomparison of the NOx monitor with Aerodyne TILDAS monitors measuring both NO and NO2. The TILDAS monitors utilize infrared diode lasers to probe individual ro-vibrational absorption lines and are considered the “gold standard” for measuring concentrations of small molecules. The monitors were deployed on the Aerodyne Mobile Laboratory during the MOOSE (Michigan Ontario Ozone Source Experiment) campaign in late 2021. The figure presented below compares the measurement of both NO2 and the sum of NO+NO2 measured by the TILDAS monitors compared with that obtained by the CAPS NO monitor at 1 second resolution. Note the excellent agreement with respect to both magnitude and time resolution. Long term comparisons indicate that correlation coefficients at 1 second resolution approach 1.
How to cite: Freedman, A., Roscioli, J., Moul, B., and Onasch, T.: Two-Channel, Fast Time-Response CAPS-Based NOx Monitor, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-3685, https://doi.org/10.5194/egusphere-egu23-3685, 2023.
The hydroperoxyl radical (HO2) plays a key role in atmospheric chemistry. It reacts with NO to generate hydroxyl radical (OH) and nitrogen dioxide (NO2), resulting in the HOx (= OH + HO2) cycle that governs the atmospheric oxidation capacity and the formation of air pollution, and a net production of ozone that determines the troposphere ozone budget. Quantitative measurement of its absolute concentration is very important. However, due to its short lifetime and low concentration (typically about 108 to 109 molecule/cm3 under atmospheric condition), most of the currently used methods are indirect methods that require chemical conversion; direct measurement remains very challenging.
The cavity ring-down spectroscopy (CRDS) technique uses high reflectivity mirrors to increase the effective absorption pathlength to tens of kilometers, enabling very high detection sensitivity; the absolute concentration of the target absorbers can be quantitatively determined by the Beer-Lambert law, providing a powerful tool for direct measurement of free radicals. In this work, we report the development of a portable cavity ring-down spectrometer for direct and absolute measurement of HO2 radical concentration using a distributed feedback (DFB) diode laser operating at 1506 nm. At a pressure of 100 mbar, a detection limit of ~ 7.3×107 molecule/cm3 (1σ, 10s) was achieved with a ring-down time (τ0) of 136 μs. The corresponding detection sensitivity was 1.5×10-11 cm-1, which was close to the state-of-the-art performance.
In cavity ring down spectroscopy, the coupling efficiency of the laser beam into the cavity depends on the laser frequency tuning speed and the ratio of the laser linewidth to the cavity mode width. For the DFB laser system, the laser linewidth (~ 2 MHz) was about thousands of times larger than that of the cavity mode (~ 1.2 kHz), which results in the conversion of laser phase noise into amplitude fluctuation, making the cavity injection noisy and limiting the improvement of detection sensitivity. Here, by replacing the DFB diode laser with a narrow linewidth erbium-doped fiber (EDF) laser, the amplitude fluctuation caused by the laser phase noise was reduced and the cavity mode injection efficiency was improved. The sensitivity was improved to 3.9×10-12 cm-1 with a short data-acquisition time of 0.2 s. The one order of magnitude improvement makes further ambient applications look promising.
How to cite: Zhao, W., Wang, C., Fang, B., Yang, N., Cheng, F., Hu, X., Chen, Y., Zhang, W., Fittschen, C., and Chen, W.: High-sensitivity detection of HO2 radical by cavity ring-down spectroscopy: prospects for future applications of narrow linewidth lasers, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-1963, https://doi.org/10.5194/egusphere-egu23-1963, 2023.
The balloon-borne and airborne instrument SPECIES (SPECtromètre Infrarouge à lasErs in Situ) recently built in our laboratory will be described. This is a mid-infrared absorption spectrometer, including four channels by coupling Interband or Quantum Cascade Lasers (ICLs or QCLs) to Optical-Feedback Cavity-Enhanced Absorption Spectroscopy (OF-CEAS). Using cavities of 50 cm length, this leads to very high resolution (< 0.005 cm-1) spectra and very long optical paths (> 5 km) and thus, low detection limits for the trace gases to be measured. It can contribute to the detailed description and understanding of the functioning of the free troposphere and stratosphere in terms of composition, chemical reactivity and circulation of air masses by carrying out fast (< 2 s) in-situ measurements of reactive trace gases and greenhouse gases among CO, NOx, CH2O, 12CO2, 13CO2, CH4 and N2O, at very high spatial resolution, i.e. a few meters vertically or hundred meters horizontally. Mini-SPECIES is the lightened version of SPECIES, comprising two lasers coupled to two cavities and reduced electrical power, which allows its integration in aircraft or its operation for long-duration stratospheric balloon flights (> 4 days). High accuracies are obtained when calibration in flight, or at ground before and after the flight, is performed against standards. In addition to providing reference measurements for calibration/validation of space missions, these performances can lead to in-depth characterization of particular atmospheric processes.
How to cite: Catoire, V., Jacquet, P., Chartier, M., Romanini, D., Krysztofiak, G., Ventrillard, I., and Robert, C.: SPECIES: a balloon-borne and airborne instrument coupling infrared lasers with Optical Feedback Cavity Enhanced Absorption Spectroscopy technique for atmospheric in-situ trace-gas measurements , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-12978, https://doi.org/10.5194/egusphere-egu23-12978, 2023.
A newly constructed thermal dissociation cavity ring-down spectrometer (TD-CRDS) for simultaneous measuring NO2, total peroxy nitrates (ΣPNs) and total alkyl nitrates (ΣANs) was presented. NO2 is detected directly at around 405.46 nm, ΣPNs and ΣANs are detected as NO2 after thermal decomposition at 180℃ and 360℃. The influences of the recombination reaction of RO2 radicals in two different types of heated inlets were discussed and compared, and the thermal decomposition efficiency of PNs was found to be higher with the value of 96% at the heated inlet filled with glass beads than the other (72%). Possible interferences, mainly O3 (including reactions of O3 via NO and O3 via NO2) and NOx (such as the recombination reactions of NOx and peroxy radicals at different thermal temperatures), were quantitatively characterised. The effects were found to be much weaker in the heated inlet filled with glass beads. Thus, a calibration method for measuring ΣPNs and ΣANs was established, especially to solve the accurate measurement of ΣPNs and ΣANs under high amounts of ambient NOx and O3 in China. At the time resolution of 20 s, the detection limits of the TD-CRDS instrument for NO2, ΣPNs and ΣANs are 6 pptv (1σ), 15 pptv (1σ) and 15 pptv (1σ), respectively. Finally, we applied the instrument to the Hefei field campaign, obtaining the concentration distribution and variation characteristics of ΣPNs and ΣANs.
How to cite: Lin, C., Hu, R., Xie, P., Zhang, G., Tong, J., and Liu, W.: A three-channel thermal dissociation cavity ring-down spectrometer for the continuous measurement of ambient NO2, total peroxy nitrates and total alkyl nitrates , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-10765, https://doi.org/10.5194/egusphere-egu23-10765, 2023.
Quantifying sources and sinks, as well as chemical activity of trace gases in the lower troposphere, requires accurate measurements of the concentrations of the species of interest. While there exist in-situ measurement techniques, which are highly accurate, point-like measurements are only sufficiently representative in the spatial domain for a small area. This holds true in particular in high-gradient environments, e.g., urban settings. Hence, measuring those concentrations averaged on the length scale of a few kilometers is desirable. Furthermore, quantifying emissions requires combining concentration measurements with regional transport models, which cover a comparable spatial resolution.
We present a long open-path setup that measures average concentrations on the kilometer-scale in the urban boundary layer. Our setup, which is operational since March 2022, is based on a Bruker IFS 125 HR Fourier transform spectrometer, a commercially available spectrometer, which offers high resolution and throughput. The instrument choice provides flexible and explorative experimental setups such as variable and high spectral resolution and the extension of spectral coverage from the shortwave-infrared to the near ultra-violet spectral range. Here, we present the results on CO2 and CH4 from our 2022 measurement campaign as well as analysis of the diurnal variability in comparison to the prediction of local and regional transport models.
How to cite: Schmitt, T., Kuhn, J., Pilz, L., Maiwald, R., May, M., Kleinschek, R., Edinger, P., Schmitt, S., Hase, F., Griffith, D. W. T., and Butz, A.: Long open-path measurements of CO2 and CH4 with an 125HR FTS in an urban environment., EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-4403, https://doi.org/10.5194/egusphere-egu23-4403, 2023.
Laser spectrometers have shown good capability in measuring mixing ratios for atmospheric greenhouse gases (GHGs). Given the fact that spectral bands of CO2, CH4, and N2O covering from near to mid-infrared (NIR to MIR) wavelengths, and the limitations in the wavelength coverage of the laser and photodetector, it is very challenging to analyze CO2, CH4, and N2O simultaneously for most cavity-enhanced analyzers using NIR lasers. Alternative solutions, such as combining multiple quantum cascade laser (QCL) beams and analyzing all GHGs in the MIR wavelengths, would significantly increase the instrumental cost.
Here, we present a recently developed analyzer utilizing the advantages of detecting CO2/H2O in the NIR spectral region and N2O/CH4 in the MIR region, respectively. Through a unique optical design, two independent optical paths are formed in a single Herriott gas cell so that low temperature-related drift and mechanical robustness are achieved. The mixing ratios of CO2 and H2O are analyzed by a NIR laser and a photodetector at ~4995cm-1, while CH4 and N2O are analyzed by a QCL and an MCT photodetector at ~1275cm-1. The analyzer facilitates high-sensitivity, field-deployable measurements of CO2, CH4, N2O and H2O altogether in a compact, portable instrumental design. In addition, this analyzer can be completely powered by rechargeable battery, facilitating all-day in situ measurements without grid power supply.
In the laboratory, side-to-side comparisons were performed between our newly developed analyzer and another commercial gas analyzer based on cavity ring down spectroscopy (CRDS). The results showed high consistency in GHG mixing-ratio measurements with the two spectrometers. Attached to soil chambers, we also found comparable performance of two analyzers in determining GHG fluxes. In particular, we found that the presented analyzer could precisely capture transient changes in gas mixing ratios from the soil chamber. Recently, field deployment in different soil conditions, including upland forest soils and riparian soils, was carried out for simultaneous N2O, CH4, CO2 soil flux measurements. The overall results suggest that our analyzer is suitable for continuous GHG flux monitoring under variable field conditions, and shows potentials in simultaneous measurements of multiple GHG fluxes from natural ecosystems.
How to cite: Yu, L., Wang, Y., Niu, Z., Su, Z., Zheng, L., and Lin, T.-J.: A portable, high-precision optical analyzer based on hybrid laser absorption cell for simultaneous measurements of N2O, CH4, and CO2 fluxes from soils, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-5232, https://doi.org/10.5194/egusphere-egu23-5232, 2023.
The measurement of singly substituted, stable isotopologues, such as 13CO2, by mid-IR spectroscopy is well established. In addition, there is a great interest to exploit the information carried by more exotic isotopologues, i.e. of low abundance, multiply substituted (clumped) isotopic species or site-specific isotopomers. This information on isotopic composition can be used as proxy to constrain formation pathways, source attribution, temperature histories or dating (radioactive isotopes) of the respective molecules. The established method to perform such isotopic analysis is isotope ratio mass spectrometry (IRMS). This approach, however, in particular for rare isotopologues, typically requires very demanding instruments, several hours of analysis time and extensive sample preparation to separate isobaric interferences.
Here, we demonstrate an alternative analytical method based on optical interrogation of the molecules by directly probing their ro-vibrational frequencies. This makes the method inherently suitable to distinguish between isotopomers (structural isomers). Furthermore, we propose a low temperature approach that substantially reduces the spectral interferences due to hot-band transitions of more abundant isotopologues. The effectiveness and versatility of this strategy are highlighted by three different applications: i) high-precision mid-IR measurements of clumped 12C18O2, ii) the detection of 14CO2 in enriched CO2 samples, and iii) a new scheme for determination of the intramolecular distribution (terminal and central positions) of 13C in propane.
We developed a quantum cascade laser (QCL) spectrometer using a Stirling-cooled circular multipass absorption cell. The distributed feedback (DFB) QCL is driven in intermittent continuous wave (iCW) mode [1] with a repetition rate of 6.5 kHz. Its beam passes through a compact segmented circular multipass cell (SC-MPC) [2] with an optical path length of 6 m. The SC-MPC is placed in a vacuum chamber that is maintained at 5ּ 10-5 mbar and cooled down to 150 K.
The precision in the ratios [12C18O2]/[12C16O2] and [12C16O18O]/[12C16O2] is 0.05 %₀ with 25 s integration time. Its accuracy is confirmed by agreement with literature values of the equilibrium constant, K, of the exchange reaction for CO2 samples equilibrated at 300 K and 1273 K [3].
As proof of concept, we adapted the system to allow the detection of the radiocarbon 14C in enriched CO2 samples. Due to its ultra-low abundance (10-12), the absorption signatures of this isotopic species is completely hidden by the spectral contributions of the other, more abundant, CO2 isotopologues. Therefore, it is the perfect candidate for low-temperature spectroscopy. We present first results on 14CO2 with a precision of 50 ppt.
And finally, we demonstrate the first high-resolution spectra of propane and its site-specific isotopomers (1-13C and 2-13C). We distinguish their individual contributions to the overall absorption spectrum and show a precision better than 0.1 ‰ for both isotopomer ratios (2-13C)/12C and (1-13C)/12C.
[1] M. Fischer et al., Opt. Express, 22(6), 7014–7027 (2014), doi: 10.1364/OE.22.007014.
[2] M. Graf, L. Emmenegger, and B. Tuzson, Opt. Lett., 43(11), 2434-2437, (2018), doi: 10.1364/OL.43.002434.
[3] A. Nataraj et al. Opt. Express 30, 4631-4641 (2022): doi.org/10.1364/OE.447172.
How to cite: Emmenegger, L., Nataraj, A., Gianella, M., Faist, J., and Tuzson, B.: Low-temperature mid-IR absorption spectroscopy for isotopomer-specific measurements , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-16250, https://doi.org/10.5194/egusphere-egu23-16250, 2023.
Methane (CH4) is the second strongest anthropogenic greenhouse gas in terms of radiative forcing after carbon dioxide (CO2). It has a relatively short atmospheric lifetime for a greenhouse gas (~9 years)and so is an attractive target for near-term climate mitigation strategies. While the total amount fraction of atmospheric CH4 is currently measured by atmospheric monitoring stations to calculate global and regional budgets, it is not currently possible to distinguish the total amount of CH4 emitted by individual sectors. Different sources emit CH4 with unique isotope ratios, and so continuous isotope ratio measurements have the potential to provide the data needed to disaggregate emissions sources.
We have developed Boreas, an automated field deployable CH4 preconcentrator coupled to a laser spectrometer able to provide continuous, high frequency measurements of both δ 13C (CH4) and δ 2H (CH4) and the total CH4 amount fraction in ambient air. Boreas was deployed to a UK atmospheric monitoring site located in Heathfield, East Sussex, in May 2021.
We compare atmospheric measurements of δ13C(CH4) and δ2H(CH4) made from Spring 2021 to Spring 2023 with equivalent model output and analyse similarities and differences in the context of currently known isotopic source signatures in Europe. We also consider potential future CH4 emission scenarios and show how these measurements could be used under future emission reduction strategies.
How to cite: Safi, E., Rennick, C., Chung, E., and Arnold, T.: A novel Laser-based technique for in-situ automated measurements of atmospheric CH4 isotopologues and implications for current and future emission scenarios , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-12554, https://doi.org/10.5194/egusphere-egu23-12554, 2023.
We will present the preliminary results of the CarbonSurvey project (Towards the Next Generation of Sensors for Surveying the Atmospheric Carbon Cycle). As outlined by the European Commission green report in the framework of the Operational Anthropogenic CO2 Emissions Monitoring and Verification Support (MVS) capacity, the existing ground-based networks currently do not meet all the operational requirements for the Copernicus CO2 MVS capacity due to the lack of in situ measurement data from urban areas and other emission hot spots. The main expected contribution of this project is to address this weakness through the development of a new generation of instruments to enable unprecedented CO2 monitoring capabilities, the biggest GHG contributor to human-caused global warming. The necessary scientific and technical contributions required to reach the main goal of the project involve two complementary developments: (i) firstly, a gas analyzer capable of obtaining the vertical profile (with resolution in altitude) of CO2 concentration. The system, which is based on the Laser Heterodyne Radiometry (LHR) technique, will operate from the Earth's surface analyzing the effect in the spectrum of the received sunlight of the atmospheric components to accurately find the distribution of the concentration of CO2 in the atmospheric column. Thus, this instrument will provide a characterization of the CO2 in the atmospheric volume located above the measurement site. Secondly, (ii) the project aims to develop Photacoustic Spectroscopy (PAS) cost-competitive photonic solution for in situ urban GHG measurements. As a main difference with today’s commercially available instrumentation, the system proposed, based on a compact photoacoustic sensing cell, will combine small-size, high sensitivity, and a straightforward field deployment capacity. This directly enables the possibility of providing an accurate, and potentially gap-free, map of the concentration of gases at ground level. These two sets of instruments provide indeed complementary information for a full reconstruction of the map of CO2 around the areas of interest. It is important to remark that both instrument designs will be equipped as well with an important additional feature: the ability to determine the isotopic fingerprint of CO2 in order to discern between natural and anthropogenic CO2 sources, such as fossil fuel combustion or biogenic respiration.
The CarbonSurvey project is funded by the Spanish State Research Agency, it started December 2022 and last until November 2024. We will present the sensors design and the preliminary laboratory results. By the end of the project, we will have both sensor prototypes fully operational and calibrated at the Izaña Atmospheric center. Moreover, the sensing systems will be specifically designed for a straightforward in situ deployment in different areas of interest, providing full coverage of the most important blind spots existing today. This new generation of sensors could establish the necessary basis to guide decision-making policies in the green transition process ahead.
How to cite: Ruiz-Llata, M., Martín-Mateos, P., Bonilla-Marique, O., Moreno-Oyervides, A., Moreno-Sanoyan, Y., and García, O.: Advances and results of two novel sensors for Surveying the Atmospheric Carbon Cycle, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-15362, https://doi.org/10.5194/egusphere-egu23-15362, 2023.
George Washington University and Mesa Photonics are developing and deploying a Laser Heterodyne Radiometer (LHR) that simultaneously measures CO2, CH4, H2O, and O2 mixing ratios throughout the troposphere and lower stratosphere. Spectral fits are constrained by fitting the oxygen spectral line shape – which depends only on pressure and temperature – to improve GHG retrieval precision and provide dry-air corrections. This constraint is achieved by fitting pressure and temperature profiles obtained from the meteorology data measured by radiosondes (vertical resolution ranging from 5-500 m) as part of NOAA’s Integrated Global Radiosonde Archive (IGRA).
Atmospheric spectra are simulated for the column using a spectral simulation package (“LahetraSim”) that uses parameters from the HITRAN spectral database to model spectra through the HITRAN Application Programming Interface (HAPI). Integrated path absorption spectra are calculated using the initial sun angle and estimated radiosonde pressure and temperature profiles. Concentration profiles for CO2, CH4, and H2O can then be iterated on their vertical distributions and refining the pressure and temperature profiles to best fit the oxygen spectrum.
Here we present a comparison of our spectral simulation software to that of an alternative method that has been presented for LHR data processing which makes use of the Planetary Spectrum Generator (PSG) API. Spectral simulations are generated using several atmospheric databases, templates, and transfer models. This tool allows for the extraction of Modern Era Retrospective Analysis, Version 2 (MERRA-2) vertical profiles of pressure and temperature and species abundances from HITRAN. Two limitations of the MERRA-2 database are the latency of approximately 2 months for the latest data availability and the coarse vertical resolution (~1 km) of the available data. Another benefit of our approach is that approximation of both Planetary Boundary Layer (PBL) and Tropopause Heights can be extracted from the temperature and pressure profiles and these heights can be iterated to refine atmospheric layers; thus increasing their relevance of LHR to GHG modeling.
How to cite: Miller, J. H., Flores, M., Bomse, D., and Gomez, A.: An Analysis of Spectral Simulation Methods for Laser Heterodyne Radiometry for the Vertical Profiling of Greenhouse Gas (GHG) Mixing Ratios, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-16612, https://doi.org/10.5194/egusphere-egu23-16612, 2023.
Posters on site: Fri, 28 Apr, 10:45–12:30 | Hall X5
In the case of large industrial complexes, there are state management equipment to monitor pollutants emitted from chimneys, but there are undetected sources of pollution, such as leaks during processes, leaks from pipes, and leaks from unsealed warehouses, except for chimneys. In this study, mobile observation was conducted using SOF, Sky DOAS, in-situ MeDOAS, and MeFTIR equipment. The observation method used in this study is fence line monitoring, which surrounds a large factory area and observes both the upwind and downwind sides. method of observation. The observation site was conducted in July and August 2021 at the Yeosu Industrial Complex located in Yeosu, Jeollanam-do, South Korea, one of the three largest industrial complexes in South Korea. In order to find out whether and the extent of leakage, four areas where Telemonitoring System(TMS), a chimney measuring device managed by the Korea Environment Corporation, exist were designated as observation sites. The results observed for the same period of time were compared for SO2 and NO2, which are substances with overlapping measurement items of mobile monitoring vehicle(MMV) and TMS. Although a direct comparison was not possible because the MMV expresses the emission per hour and the TMS expresses the emission concentration, it was confirmed that leaks that were not captured by the TMS on a specific date appeared as a result of the MMV measurement. This study confirmed that even in industrial complexes where TMS is installed for management purposes, air pollution and economic losses due to leaks can be reduced if fan line monitoring is conducted to detect unexpected leaks.
acknowledgment
This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT) (No. 2018R1D1A3B07048047)
How to cite: Sim, J., Kim, D., Shin, J., Lee, Y., Joo, S., Kim, J., Park, G., and Noh, Y.: Comparison of Fence Line Monitoring by mobile monitoring vehicle and Chimney Measuring Devices in Large Industrial Complexes, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-3245, https://doi.org/10.5194/egusphere-egu23-3245, 2023.
The isotopic composition of gaseous species can provide critical information regarding the age and chemical or physical origin of sample material. However, the challenge of maintaining isotope abundance scales – generated by comparing sample measurements to those of a reference material having finite quantity and stability – may limit inter-laboratory agreement and consequently the uncertainty evaluation of new measurement methods. Here we will present progress towards realization of artifact-free isotope scales and rapid measurements of isotopic composition enabled by absolute SI-traceable measurement schemes.
We will discuss how cavity ring-down spectroscopy techniques, capable of highly precise and accurate measurements of transition-resolved peak areas, can be leveraged in combination with quantum chemical calculations of transition moments to enable measurement of molecular isotopologue ratios [1]. We will also introduce direct frequency comb spectroscopy methods for rapid and precise measurement of isotopic abundance [2]. This discussion will include demonstrations in the near- and mid- infrared spectral regions employing cross-dispersed spectrometers. Implications for carbon, nitrogen, and oxygen isotopic analysis will be presented.
Applications of these SI-traceable measurement approaches include accurate source apportionment and greenhouse gas inventories, radiocarbon dating, isotope forensics, with the potential for high-impact contributions to emerging advances in exoplanetary studies and astrophysics.
[1] A. J. Fleisher, H. Yi, A. Srivastava, et al., Nat. Phys. 2021, 17, 889-893
[2] D. M. Bailey, G. Zhao, and A. J. Fleisher, Anal. Chem. 2020, 92 (20), 13759–13766
How to cite: Bailey, D. M., Srivastava, A., Hodges, J., and Fleisher, A.: Artifact-Free Measurements of Isotopic Composition for Atmospheric and Planetary Gas Analysis, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-3470, https://doi.org/10.5194/egusphere-egu23-3470, 2023.
Correspondence: Min Qin(mqin@aiofm.ac.cn)
Abstract: A measurement campaign using long-path differential optical absorption spectroscopy (LP-DOAS) instrument at Hefei Xinqiao International Airport to investigate the regional concentrations of various trace gases in the airport’s northern area and the variation characteristics of the gas concentrations during an aircraft’s taxiing and take-off phases. The total light path of the LP-DOAS system was about 964 meters and the time resolution of the LP-DOAS instrument was approximately 10 seconds. The measured light path of the LP-DOAS passed through an aircraft taxiway and take-off runway concurrently without affecting aircraft operations. The results of NO2 and SO2 pollution peaks were clearly visible, and their timing was well matched to the time the aircraft crossed the light path. While the aircraft take-offs increased the regional average NO2 concentrations by 10-20 ppbV and flight take-offs increased the regional average SO2 concentrations by 1-5 ppbV, the overall pollution levels in the airport area were low due to the airport's openness and rapid dispersion of pollutants, and the maximum hourly average NO2 and SO2 concentrations during the observation period were better than the Class 1 ambient air quality standards in China. Additionally, we discovered that the NO2 and SO2 emissions from the Boeing 737-800 aircraft used in this experiment were positively related to the age of the aircraft.
Acknowledgements: This work was supported by the Plan for Anhui Major Provincial Science & Technology Project (Grant No. 202203a07020003), the Anhui Provincial Key R&D Program (No.202104i07020010) and the HFIPS Director’s Fund (Grant No. YZJJQY202205).
How to cite: Duan, J., Qin, M., Fang, W., Liao, Z., Gui, H., Xie, P., and Liu, W.: Detection of the regional concentrations of various trace gases using LP-DOAS at Hefei Xinqiao International Airport, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-5538, https://doi.org/10.5194/egusphere-egu23-5538, 2023.
Nitrogen dioxide (NO2) is a major air pollutant that can lead to increased risks of lung cancer, cardiovascular mortality, and a 50% increased likelihood of children developing asthma. Expanding the scope and range of NO2 measurements is therefore desirable to quantify NO2 levels and emissions in different settings. Current research and regulatory instruments are too expensive and bulky for widespread deployment and personal exposure measurements, while low-cost sensors do not have the required sensitivity, accuracy, and response time for many applications.
Here we describe a spectroscopic, optical cavity approach to sensitively quantify NO2 based on the differential absorption at two nearby wavelengths. The system uses a modulated blue LED, an optical cavity for high absorption sensitivity, and lock-in amplification to measure the light transmitted through the cavity. Careful spectral filtering is needed to remove unwanted wavelengths. We report the system performance and Allan deviation of the system, and compare the system response against a standard IBBCEAS set-up for in situ measurements of NO2. Strategies to improve the instrument performance and reduce sensor size and cost are discussed.
How to cite: Halpin, E. F. and Venables, D. S.: Development of a spectroscopic sensor for accurate, real-time monitoring of personal exposure to nitrogen dioxide, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-6065, https://doi.org/10.5194/egusphere-egu23-6065, 2023.
The intensive development of industry, agriculture, and transportation cause many issues related to the negative impact on the environment and human health. Due to increasing concentrations of greenhouse gases (CH4, CO2, etc.), the effects of global warming are already being observed. Research that addresses the challenges of climate change mitigation and creates science-based assumptions for new environmental monitoring systems and technologies is becoming more and more relevant.
A new DronLab system for measuring methane and other greenhouse gases is currently in development. The system consists of a high-lifting power drone designed to carry the quantum cascade laser (QCL), parabolic mirror, and detector and a smaller quadcopter drone designed to lift the retroreflector to reflect the mid-IR laser pulse back towards the first drone. DronLab system will allow simultaneous measurement and visualization of methane dispersion and emission from a point source.
Methane concentration would be measured at 3.37 µm using a quantum cascade laser. This system will provide the ability to measure the pollutants using variable optical path lengths. A changeable optical path would result in a higher dynamic range of the methane detection system.
How to cite: Butkus, L., Ežerinskis, Ž., Vaitekonis, Š., Plotnikov, A., Pabedinskas, A., Plukis, A., and Remeikis, V.: UAV-based atmospheric methane detection system, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-8491, https://doi.org/10.5194/egusphere-egu23-8491, 2023.
According to World Health Organization, nowadays almost the entire global population (99%) breathes air that threatens its health (WHO, 2022), The greatest concern is related to air pollution by particles and nitrogen dioxide, people living in cities facing every day’s unhealthy levels of these pollutants. Due to their multitude of sources, natural (mineral dust, sea salt, volcanoes, etc.) and anthropogenic (traffic, industry, constructions, agricultural activities, etc.), atmospheric particulate matter (PM) levels and physical properties vary greatly in time and space. Here we investigate the magnetic properties of PM10 (PM less than 10 µm) sampled in three different locations from Romania chosen so as to reflect as much as possible different origin of atmospheric particles. We use non-linear Preisach maps in tandem with Scanning Electron Microscopy (SEM) coupled with Energy-Dispersive X-ray spectroscopy (EDS), SEM/EDS, to specify more precisely domain states and characteristic magnetic signature of magnetic grains in PM10 fraction. PM10 aerosol samples were collected at three different sites in southern Romania: Bucharest site as urban, heavy impacted by traffic in the very center of the city, Magurele as suburban, under the influence of Bucharest and of the agricultural activities in the surrounding areas and Matasari, a rural site located in south-western Romania that was heavily impacted by the industrial activities at the open-pit coal mines located in the proximity. Our study highlighted three main types of magnetic mineral pollutants in the PM10 samples from Romanian industrial, urban traffic and suburban environments.
Acknowledgment
AD and GI gratefully acknowledge the funding from the NO Grants 2014-2021, under Project contract no. 31/2020, EEA-RO-NO-2019-0423 project. This work was also supported by a grant of Ministry of Research, Innovation and Digitization, CCCDI - UEFISCDI, project number PN-III-P2-2.1-PED-2021-3678, within PNCDI III
How to cite: Dumitru, A., Necula, C., Dumitru, M., and Iorga, G.: Magnetic characterization of PM10 using non-linear Preisach maps. Toward domain state identification of magnetic anthropogenic particles, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-8892, https://doi.org/10.5194/egusphere-egu23-8892, 2023.
Light absorbing particulate emissions, known as black carbon (BC) or brown carbon (BrC), are major contributors to the atmospheric aerosol and have a significant impact on climate forcing. The spectral light absorption coefficient of these particles, which is essential for understanding their impact on the climate, can vary greatly depending on the combustion process and atmospheric aging, particularly in the Arctic where concentrations of BC and BrC are low but the climate is sensitive to changes in the atmospheric aerosol. Traditional filter-based methods for characterizing light absorbing aerosol can be prone to errors in environments where the relationship between particle light scattering and absorption is high due to cross-sensitivity to co-deposited light scattering particles. The photoacoustic absorption spectroscopy (PAS) method is less sensitive to particle light scattering and has a high measurement precision and accuracy, but is not widely used for long-term monitoring due to ist assumed lack of sensitivity and robustness.
The Photoacoustic Aerosol Absorption Spectrometer PAAS-4λ has been developed for use in unattended air quality monitoring stations and utilizes four wavelengths coupled to a single acoustic resonator in a compact and robust design. It has a low detection limit of below 0.1 Mm-1 and has been calibrated in the laboratory using NO2/air mixtures and Nigrosin aerosol. The PAAS-4λ has been validated at an air quality monitoring station in the European Arctic and its performance during 12 months of deployment is presented. Comparisons with filter-based photometers demonstrate the capabilities and value of the PAAS-4λ for both long-term monitoring and the validation of filter-based instruments.
How to cite: Schnaiter, M., Linke, C., Asmi, E., Servomaa, H., Hyvärinen, A.-P., Ohata, S., Kondo, Y., and Järvinen, E.: The Four-Wavelength Photoacoustic Aerosol Absorption Spectrometer PAAS-4λ, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-9167, https://doi.org/10.5194/egusphere-egu23-9167, 2023.
Measuring atmospheric water vapor is an essential but challenging task. The naturally occurring concentrations varies over four orders of magnitude and adsorption and desorption processes on sensors and in sampling systems can distort and attenuate the signal. During airborne measurements H2O concentration gradients that exceed 1400 ppm/s are common and pose an additional challenge [1]. Despite the highly dynamic conditions, especially on research aircrafts like HALO, instrument calibration under static conditions is the norm. This leads to unknown sensor behavior in dynamic conditions and makes it difficult to reliably correct or even identify the influences of dynamic concentration changes on the data. With dynH2O we present an approach to characterize the dynamic response behavior of hygrometers in a metrological and traceable way [2]. dynH2O consists of A) a preparative unit to generate fast and repeatable steps in the water vapor concentration. To generate the concentration steps fast pneumatic valves are used to switch between the flow of two humidity generators which is than mixed into a base flow of dry air. This approach allows the lower and upper bound of the concentration step to be selected independently over a flow range from 13 to 120 standard liters per minute (= sl/min). The generated gas mixture is than passed into B) a flow channel optimized to create a flat concentration front which is monitored by C) an open-path, calibration-free direct Tunable Diode Laser Absorption Spectroscopy (dTDLAS) hygrometer. The dTDLAS reference instrument is operated as a traceable optical gas standard with a temporal resolution of up to 1000 Hz and no sampling delays due to the use of a rotational symmetric multipath cell which is embedded into the walls of the flow channel of the setup. A device under test (DUT) is placed directly behind the optical measurement plane. To characterize the DUT the ideal sensor response is simulated based on the data from the optical reference instrument. The simulated ideal DUT response is used to separate the dynamic response from the setup from the response of the DUT, making the results independent from the setup and easier to transfer to the field. A first order lowpass is used to model the corrected response behavior of the DUT. The characterization of a polymer-based hygrometer will be presented and possibilities to apply the characterization to correct or mitigate the nonlinear distortions of the time axis caused by dynamic H2O concentration changes, by means of different deconvolution methods, will be discussed.
[1] Buchholz, B.; Afchine, A.; Klein, A.; Schiller, C.; Krämer, M.; Ebert, V. HAI, a new airborne, absolute, twin dual-channel, multi-phase TDLAS-hygrometer: background, design, setup, and first flight data. Atmos. Meas. Tech. 2017, 10, 35–57, doi:10.5194/amt-10-35-2017.
[2] Witt, F.; Bubser, F.; Ebert, V.; Bergmann, D. C9.1 Temporal Hygrometer Characterization: Design and First Test of a New, Metrological Dynamic Testing Infrastructure. In System of Units and Metreological Infrastructure. SMSI 2021, digital, 5/3/2021 - 5/6/2021; AMA Service GmbH: Wunstorf, Germany, 2021 - 2021; pp 308–309.
How to cite: Witt, F. and Ebert, V.: dynH2O: A Metrological Approach to Manage the Effects of Dynamic H2O Concentration Changes on Hygrometers in the Field, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-17526, https://doi.org/10.5194/egusphere-egu23-17526, 2023.
A novel instrument based on broadband cavity enhanced absorption spectroscopy has been developed using a supercontinuum broadband light source, which showcases its ability in simultaneous measurements of the concentration of NO2 and the extinction of particulate matter (PM). Side-by-side intercomparison was carried out with the reference NOx analyzer for NO2 and OPC-N2 particle counter for particulate matter, which shows a good linear correlation with r2 > 0.90. Measurement limits (1σ) of the developed instrument were experimentally determined to be 230 pptv in 40 s for NO2 and 1.24 Mm-1 for the PM extinction in 15 s, respectively.
This work provides a promising method in simultaneously monitoring atmospheric gaseous compounds and particulate matter, which would further advance our understanding on gas-particle heterogeneous interactions in the context of climate change and air quality.
Experimental details and the preliminary results will be discussed and presented.
Acknowledgments
The authors thank the financial supports from the French national research agency (ANR) under the MABCaM (ANR-16-CE04-0009), the CaPPA (ANR-10-LABX-005) contracts, the CPER ECRIN program, and the EU H2020-ATMOS project.
How to cite: Chen, W., Wang, G., Meng, L., Gou, Q., Hanoune, B., Crumeyrolle, S., Fagniez, T., Coeur, C., and Akiki, R.: A Broadband Cavity-Enhanced Absorption Spectrometer for Simultaneous measurements of NO2 and particulate matter, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-12051, https://doi.org/10.5194/egusphere-egu23-12051, 2023.
Water vapor (H2O) in the upper troposphere-lower stratosphere (UTLS) is of great importance to the Earth's radiative balance. Yet, accurate measurements of H2O in this region are notoriously difficult, and significant discrepancies were found in the past between different techniques (both in-situ and remote sensing). Currently, cryogenic frostpoint hygrometry is considered as the reference method for balloon-borne measurements of UTLS H2O [1]. However, these devices must be fundamentally reconceived due their use of fluoroform (HFC-23) as cooling agent, which has to be phased out due to its high global warming potential. There is thus an urgent need for alternative, reliable technologies to monitor UTLS H2O, e.g. in long-term global observing networks, such as the GCOS Reference Upper Air Network (GRUAN).
Here we present a new mid-IR quantum-cascade laser absorption spectrometer for balloon-borne measurements of UTLS H2O (ALBATROSS). The spectrometer incorporates a specifically designed segmented circular multipass cell (SC-MPC) that allows for an optical path length of 6 m [2], and it fulfills stringent requirements in terms of mass (< 3.5 kg), size, and temperature resilience. Two successful test flights demonstrated the instrument's outstanding capabilities under real atmospheric conditions up to 28 km altitude [3].
During flights, the instrument experiences a harsh environment with up to 80 K temperature variations and two orders of magnitude change in pressure and H2O amount fraction. To achieve reliable and SI-traceable, we determined the spectral performance and the accuracy of the retrieved amount fractions of ALBATROSS at UTLS-relevant conditions using a dynamic-gravimetric permeation method [4]. SI-traceable reference mixtures were generated with H2O amount fractions as low as 2.5 µmol/mol (or parts per million, ppm) in synthetic air. The results show that ALBATROSS achieves an accuracy better than ±1.5 % at all investigated pressures (30–250 mbar) and H2O amount fractions (2.5–35 ppm). The 1 s relative precision is better than 0.3 %, while 5 nmol/mol (i.e., parts per billion, ppb) is reached by averaging for 100 s. Furthermore, ALBATROSS reaches a linear response within ±2 ppm up to 180 ppm H2O.
To achieve this level of performance, the Voigt profile was found to be inadequate. Therefore, we empirically determined all parameters needed to implement the quadratic speed-dependent Voigt profile (qSDVP), which accounts for speed-dependent collision broadening. The qSDVP more accurately captures the H2O line shape at all pressure conditions, and thus significantly improves the accuracy of the retrieved water vapor amount fraction.
Overall, ALBATROSS achieves an unprecedented level of accuracy and precision for a balloon-borne hygrometer, and it demonstrates the exceptional potential of mid-IR laser absorption spectroscopy for in-situ measurements of UTLS H2O. Further in-flight validation campaigns from Lindenberg (Germany) and Payerne (Switzerland) are currently in preparation.
[1] Brunamonti et al., J. Geophys. Res. Atmos., 2019, 124, 13, 7053-7068.
[2] Graf et al., Atmos. Meas. Tech., 2021, 14, 1365-1378.
[3] Graf, Emmenegger and Tuzson, Opt. Lett., 2018, 43, 2434-2437.
How to cite: Tuzson, B., Brunamonti, S., Graf, M., Bühlmann, T., and Emmenegger, L.: SI-traceable balloon-borne measurements of water vapor in the upper atmosphere, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-13161, https://doi.org/10.5194/egusphere-egu23-13161, 2023.
Posters virtual: Fri, 28 Apr, 10:45–12:30 | vHall AS
An all-fiber coupled laser heterodyne radiometer (LHR), using a wideband tunable external cavity diode laser (1500–1640 nm) as local oscillator laser, was developed for ground-based remote sensing of carbon dioxide. Optimal absorption lines and transmission spectra of carbon dioxide in this wavelength range were determined. High sensitivity of the LHR was achieved by using a balanced photodetector to suppress the relative intensity noise of the local oscillator laser. The noise model of the highly sensitive LHR was analyzed and compared with the traditional LHR using single photodetector [1-2]. Finally, field campaigns were performed on the roof of the platform of IRENE building in Dunkerque (51.05°N/2.34°E). The measured LHR spectra in the atmospheric column are compared, in good agreement, with referenced Fourier-transform infrared spectra from the TCCON observation network and with the simulation spectra resulting from an atmospheric transmission modeling. Experimental details including noise analysis and LHR spectra will be discussed and presented.
Acknowledgments
The authors thank the financial supports from the LABEX CaPPA project (ANR-10-LABX005), the CPER ECRIN program, the EU H2020-ATMOS project as well as the funding from China Scholarship Council (CSC).
References
[1] T. G. Blaney. "Signal-to-noise ratio and other characteristics of heterodyne radiation receivers", Space Science Reviews 17 (1975) 691-702.
[2] F. Shen, G. Wang, J. Wang, T. Tan, G. Wang, P. Jeseck, Y.-V. Te, X. Gao, W. Chen. "A transportable mid-infrared laser heterodyne radiometer operating in the shot-noise dominated regime", Opt. Lett.46 (2021) 3171-3174.
How to cite: Wei, T., Wang, J., Shen, F., Tan, T., Cao, Z., Gao, X., Jeseck, P., Te, Y.-V., Plus, S., Dong, L., Miller, H., and Chen, W.: Highly sensitive laser heterodyne radiometer based on a balanced photodetector for carbon dioxide measurement in the atmospheric column, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-14492, https://doi.org/10.5194/egusphere-egu23-14492, 2023.
The use of high reflectivity dielectric mirrors to form a high finesse optical cavity allows one to achieve long optical path lengths of up to several kilometres for high-sensitivity spectroscopy applications [1,2]. The high reflectivity of a dielectric mirror is achieved via constructive interference of the Fresnel reflection at the interfaces produced by multilayer coatings of alternate high and low refractive index materials [3]. This wavelength-dependent coating limits the bandwidth of the mirror's high reflectivity to only a few percent of the designed central wavelength.
We report on the recent development of a novel optical cavity based on prisms as cavity reflectors [4-6], which offers a high-finesse optical cavity operating in a broadband spectral region from 400 to more than 1600 nm [7] and provides a very suitable high-sensitivity spectroscopic technique for frequency-comb application.
Acknowledgments : This work is supported by the French national research agency (ANR) under the MABCaM (ANR-16-CE04-0009), the CaPPA (ANR-10-LABX-005), the ICAR-HO2 (ANR-20-CE04-0003) contracts, and the regional ECRIN program.
References
[1] S. S. Brown, Chem. Rev. 103 (2003) 5219-5238.
[2] M. Mazurenka, A. J. Orr-Ewing, R. Peverallb and G. A. D. Ritchie, Annu. Rep. Prog. Chem. Sect. C101 (2005) 100-142.
[3] G.R. Fowles, Introduction to Modern Optics, 2nd ed. (Rinehart and Winston, 1975), p. 328.
[4] H. Moosmuller, App. Opt. 37 (1998) 8140-8141.
[5] P. S. Johnston and K. K. Lehmann, Opt. Express 16 (2008) 15013-15023.
[6] B. Lee, K. Lehmann, J. Taylor and A. Yalin, Opt. Express 22 (2014) 11583-11591.
[7] G. Wang, A. Yalin, C. Coeur, S. Crumeyrolle, R. Akiki, E. Fertein, W. Chen, 6th International Workshop on Infrared Technologies, October 29-30, 2019, Princeton, New Jersey, USA.
How to cite: Cui, R., Wang, G., Yalin, A., Meng, L., Coeur, C., Dong, L., and Chen, W.: Development of a high-finesse broadband optical cavity using prism based on total internal reflection for applied spectroscopy, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-5828, https://doi.org/10.5194/egusphere-egu23-5828, 2023.
