scholarly journals The novel HALO mini-DOAS instrument: inferring trace gas concentrations from airborne UV/visible limb spectroscopy under all skies using the scaling method

2017 ◽  
Vol 10 (11) ◽  
pp. 4209-4234 ◽  
Author(s):  
Tilman Hüneke ◽  
Oliver-Alex Aderhold ◽  
Jannik Bounin ◽  
Marcel Dorf ◽  
Eric Gentry ◽  
...  
Keyword(s):  
Trace Gases ◽  
Trace Gas ◽  
The Novel ◽  
Scaling Method ◽  
Mixing Ratios ◽  
Research Mission ◽  
Model Predictions ◽  
First Results ◽  
Research Aircraft ◽  
Spectral Ranges

Abstract. We report on a novel six-channel optical spectrometer (further on called mini-DOAS instrument) for airborne nadir and limb measurements of atmospheric trace gases, liquid and solid water, and spectral radiances in the UV/vis and NIR spectral ranges. The spectrometer was developed for measurements from aboard the German High-Altitude and Long-Range (HALO) research aircraft during dedicated research missions. Here we report on the relevant instrumental details and the novel scaling method used to infer the mixing ratios of UV/vis absorbing trace gases from their absorption measured in limb geometry. The uncertainties of the scaling method are assessed in more detail than before for sample measurements of NO2 and BrO. Some first results are reported along with complementary measurements and comparisons with model predictions for a selected HALO research flight from Cape Town to Antarctica, which was performed during the research mission ESMVal on 13 September 2012.

scholarly journals The novel HALO mini-DOAS instrument: Inferring trace gas concentrations from air-borne UV/visible limb spectroscopy under all skies using the scaling method

2017 ◽  
Author(s):  
Tilman Hüneke ◽  
Oliver-Alex Aderhold ◽  
Jannik Bounin ◽  
Marcel Dorf ◽  
Eric Gentry ◽  
...  
Keyword(s):  
Trace Gases ◽  
Trace Gas ◽  
The Novel ◽  
Scaling Method ◽  
Mixing Ratios ◽  
Research Mission ◽  
Model Predictions ◽  
First Results ◽  
Research Aircraft ◽  
Spectral Ranges

Abstract. We report on a novel 6 channel optical spectrometer (further on called mini-DOAS instrument) for aircraftborne nadir and limb measurements of atmospheric trace gases, liquid and solid water, and spectral radiances in the UV/vis and nearIR spectral ranges. The spectrometer was developed for measurements from aboard the HALO (http://www.halo.dlr.de/) research aircraft during dedicated research missions. Here we report on the relevant instrumental details and the novel scaling method used to infer the mixing ratios of UV/vis absorbing trace gases from their absorption measured in limb geometry. The uncertainties of the scaling method are assessed for NO2 and BrO measurements. Some first results are reported along with complementary measurements and comparisons with model predictions for a selected HALO research flight from Cape Town to Antarctica, which was performed during the research mission ESMVal on 13 September 2012.

Trace gases and organic aerosol at a rural site in Vietnam during large scale biomass burning

2021 ◽  
Author(s):  
Simone M. Pieber ◽  
Dac-Loc Nguyen ◽  
Hendryk Czech ◽  
Stephan Henne ◽  
Nicolas Bukowiecki ◽  
...  
Keyword(s):  
Air Quality ◽  
Chemical Composition ◽  
Biomass Burning ◽  
Large Scale ◽  
Trace Gases ◽  
Organic Aerosol ◽  
Trace Gas ◽  
Rural Site ◽  
Air Masses ◽  
Mixing Ratios

<p>Open biomass burning (BB) is a globally widespread phenomenon. The fires release pollutants, which are harmful for human and ecosystem health and alter the Earth's radiative balance. Yet, the impact of various types of BB on the global radiative forcing remains poorly constrained concerning greenhouse gas emissions, BB organic aerosol (OA) chemical composition and related light absorbing properties. Fire emissions composition is influenced by multiple factors (e.g., fuel and thereby vegetation-type, fuel moisture, fire temperature, available oxygen). Due to regional variations in these parameters, studies in different world regions are needed. Here we investigate the influence of seasonally recurring BB on trace gas concentration and air quality at the regional Global Atmosphere Watch (GAW) station Pha Din (PDI) in rural Northwestern Vietnam. PDI is located in a sparsely populated area on the top of a hill (1466 m a.s.l.) and is well suited to study the large-scale fires on the Indochinese Peninsula, whose pollution plumes are frequently transported towards the site [1]. We present continuous trace gas observations of CO<sub>2</sub>, CH<sub>4</sub>, CO, and O<sub>3</sub> conducted at PDI since 2014 and interpret the data with atmospheric transport simulations. Annually recurrent large scale BB leads to hourly time-scale peaks CO mixing ratios at PDI of 1000 to 1500 ppb around every April since the start of data collection in 2014. We complement this analysis with carbonaceous PM<sub>2.5 </sub>chemical composition analyzed during an intensive campaign in March-April 2015. This includes measurements of elemental and organic carbon (EC/OC) and more than 50 organic markers, such as sugars, PAHs, fatty acids and nitro-aromatics [2]. For the intensive campaign, we linked CO, CO<sub>2</sub>, CH<sub>4</sub> and O<sub>3</sub> mixing ratios to a statistical classification of BB events, which is based on OA composition. We found increased CO and O<sub>3</sub> levels during medium and high BB influence during the intensive campaign. A backward trajectory analysis confirmed different source regions for the identified periods based on the OA cluster. Typically, cleaner air masses arrived from northeast, i.e., mainland China and Yellow sea during the intensive campaign. The more polluted periods were characterized by trajectories from southwest, with more continental recirculation of the medium cluster, and more westerly advection for the high cluster. These findings highlight that BB activities in Northern Southeast Asia significantly enhances the regional OA loading, chemical PM<sub>2.5 </sub>composition and the trace gases in northwestern Vietnam. The presented analysis adds valuable data on air quality in a region of scarce data availability.</p><p> </p><p><strong>REFERENCES</strong></p><p>[1] Bukowiecki, N. et al. Effect of Large-scale Biomass Burning on Aerosol Optical Properties at the GAW Regional Station Pha Din, Vietnam. AAQR. 19, 1172–1187 (2019).</p><p>[2] Nguyen, D. L, et al. Carbonaceous aerosol composition in air masses influenced by large-scale biomass burning: a case-study in Northwestern Vietnam. ACPD., https://doi.org/10.5194/acp-2020-1027, in review, 2020.</p>

scholarly journals Recent improvements of long-path DOAS measurements: impact on accuracy and stability of short-term and automated long-term observations

2019 ◽  
Vol 12 (8) ◽  
pp. 4149-4169 ◽  
Author(s):  
Jan-Marcus Nasse ◽  
Philipp G. Eger ◽  
Denis Pöhler ◽  
Stefan Schmitt ◽  
Udo Frieß ◽  
...  
Keyword(s):  
Light Source ◽  
Optical Density ◽  
Measurement Accuracy ◽  
Trace Gases ◽  
Detection Limits ◽  
Trace Gas ◽  
Light Sources ◽  
Light Path ◽  
Mixing Ratios ◽  
Spectral Residual

Abstract. Over the last few decades, differential optical absorption spectroscopy (DOAS) has been used as a common technique to simultaneously measure abundances of a variety of atmospheric trace gases. Exploiting the unique differential absorption cross section of trace-gas molecules, mixing ratios can be derived by measuring the optical density along a defined light path and by applying the Beer–Lambert law. Active long-path (LP-DOAS) instruments can detect trace gases along a light path of a few hundred metres up to 20 km, with sensitivities for mixing ratios down to ppbv and pptv levels, depending on the trace-gas species. To achieve high measurement accuracy and low detection limits, it is crucial to reduce instrumental artefacts that lead to systematic structures in the residual spectra of the analysis. Spectral residual structures can be introduced by most components of a LP-DOAS measurement system, namely by the light source, in the transmission of the measurement signal between the system components or at the level of spectrometer and detector. This article focuses on recent improvements by the first application of a new type of light source and consequent changes to the optical setup to improve measurement accuracy. Most state-of-the-art LP-DOAS instruments are based on fibre optics and use xenon arc lamps or light-emitting diodes (LEDs) as light sources. Here we present the application of a laser-driven light source (LDLS), which significantly improves the measurement quality compared to conventional light sources. In addition, the lifetime of LDLS is about an order of magnitude higher than of typical Xe arc lamps. The small and very stable plasma discharge spot of the LDLS allows the application of a modified fibre configuration. This enables a better light coupling with higher light throughput, higher transmission homogeneity, and a better suppression of light from disturbing wavelength regions. Furthermore, the mode-mixing properties of the optical fibre are enhanced by an improved mechanical treatment. The combined effects lead to spectral residual structures in the range of 5-10×10-5 root mean square (rms; in units of optical density). This represents a reduction of detection limits of typical trace-gas species by a factor of 3–4 compared to previous setups. High temporal stability and reduced operational complexity of this new setup allow the operation of low-maintenance, automated LP-DOAS systems, as demonstrated here by more than 2 years of continuous observations in Antarctica.

scholarly journals CRISTA-NF measurements with unprecedented vertical resolution during the RECONCILE aircraft campaign

2012 ◽  
Vol 5 (5) ◽  
pp. 1173-1191 ◽  
Author(s):  
J. Ungermann ◽  
C. Kalicinsky ◽  
F. Olschewski ◽  
P. Knieling ◽  
L. Hoffmann ◽  
...  
Keyword(s):  
Cross Sections ◽  
Polar Vortex ◽  
The Arctic ◽  
Trace Gas ◽  
Retrieval Algorithm ◽  
Vertical Resolution ◽  
Mixing Ratios ◽  
Flight Direction ◽  
Research Aircraft ◽  
Gas Volume

Abstract. The Cryogenic Infrared Spectrometers and Telescope for the Atmosphere – New Frontiers (CRISTA-NF), an airborne infrared limb-sounder, was operated aboard the high-flying Russian research aircraft M55-Geophysica during the Arctic RECONCILE campaign from January to March 2010. This paper describes the calibration process of the instrument and the retrieval algorithm employed and then proceeds to present retrieved trace gas volume mixing ratio cross-sections for one specific flight in this campaign. We are able to resolve the uppermost troposphere/lower stratosphere for several trace gas species for several kilometres below the flight altitude (16 to 19 km) with an unprecedented vertical resolution of 400 to 500 m for the limb-sounding technique. The instrument points sideways with respect to the flight direction. Therefore, the observations are also characterised by a rather high horizontal sampling along the flight track, which provides a full vertical profile every ≈15 km. Assembling the vertical trace gas profiles derived from CRISTA-NF measurements to cross-sections shows filaments of vortex and extra-vortex air masses in the vicinity of the polar vortex. During this campaign, the M55-Geophysica carried further instruments enabling trace gas volume mixing ratios derived from CRISTA-NF to be validated by comparing them with measurements by the in situ instruments HAGAR and FOZAN and observations by MIPAS-STR. This validation suggests that the retrieved trace gas volume mixing ratios are both qualitatively and quantitatively reliable.

scholarly journals Impacts of updated spectroscopy on thermal infrared retrievals of methane evaluated with HIPPO data

2014 ◽  
Vol 7 (9) ◽  
pp. 10059-10107
Author(s):  
M. J. Alvarado ◽  
V. H. Payne ◽  
K. E. Cady-Pereira ◽  
J. D. Hegarty ◽  
S. S. Kulawik ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Trace Gases ◽  
Thermal Infrared ◽  
Trace Gas ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Spectroscopic Parameters ◽  
Mixing Ratios ◽  
Aircraft Observations ◽  
The Impact

Abstract. Errors in the spectroscopic parameters used in the forward radiative transfer model can introduce altitude-, spatially-, and temporally-dependent biases in trace gas retrievals. For well-mixed trace gases such as methane, where the variability of tropospheric mixing ratios is relatively small, reducing such biases is particularly important. We use aircraft observations from all five missions of the HIAPER Pole-to-Pole Observations (HIPPO) of the Carbon Cycle and Greenhouse Gases Study to evaluate the impact of updates to spectroscopic parameters for methane (CH4), water vapor (H2O), and nitrous oxide (N2O) on thermal infrared retrievals of methane from the NASA Aura Tropospheric Emission Spectrometer (TES). We find that updates to the spectroscopic parameters for CH4 result in a substantially smaller mean bias in the retrieved CH4 when compared with HIPPO observations. After an N2O-based correction, the bias in TES methane upper tropospheric representative values for measurements between 50° S and 50° N decreases from 56.9 to 25.7 ppbv, while the bias in the lower tropospheric representative value increases only slightly (from 27.3 to 28.4 ppbv). For retrievals with less than 1.6 DOFS, the bias is reduced from 26.8 to 4.8 ppbv. We also find that updates to the spectroscopic parameters for N2O reduce the errors in the retrieved N2O profile.

scholarly journals UAS BASED TREE SPECIES IDENTIFICATION USING THE NOVEL FPI BASED HYPERSPECTRAL CAMERAS IN VISIBLE, NIR AND SWIR SPECTRAL RANGES

2016 ◽  
Vol XLI-B1 ◽  
pp. 1143-1148 ◽  
Author(s):  
R. Näsi ◽  
E. Honkavaara ◽  
S. Tuominen ◽  
H. Saari ◽  
I. Pölönen ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Species Identification ◽  
Tree Species ◽  
The Novel ◽  
Flexible Tool ◽  
Sensing Applications ◽  
Fabry Perot ◽  
First Results ◽  
Remote Sensing Applications ◽  
Spectral Ranges

Unmanned airborne systems (UAS) based remote sensing offers flexible tool for environmental monitoring. Novel lightweight Fabry-Perot interferometer (FPI) based, frame format, hyperspectral imaging in the spectral range from 400 to 1600 nm was used for identifying different species of trees in a forest area. To the best of the authors’ knowledge, this was the first research where stereoscopic, hyperspectral VIS, NIR, SWIR data is collected for tree species identification using UAS. The first results of the analysis based on fusion of two FPI-based hyperspectral imagers and RGB camera showed that the novel FPI hyperspectral technology provided accurate geometric, radiometric and spectral information in a forested scene and is operational for environmental remote sensing applications.

scholarly journals The airborne mass spectrometer AIMS – Part 2: Measurements of trace gases with stratospheric or tropospheric origin in the UTLS

2016 ◽  
Vol 9 (4) ◽  
pp. 1907-1923 ◽  
Author(s):  
Tina Jurkat ◽  
Stefan Kaufmann ◽  
Christiane Voigt ◽  
Dominik Schäuble ◽  
Philipp Jeßberger ◽  
...  
Keyword(s):  
Nitrogen Oxide ◽  
Mass Spectrometer ◽  
Chemical Ionization ◽  
Trace Gases ◽  
Measurement Techniques ◽  
Ion Source ◽  
Trace Gas ◽  
Ionization Mass ◽  
Custom Made ◽  
Research Aircraft

Abstract. Understanding the role of climate-sensitive trace gas variabilities in the upper troposphere and lower stratosphere region (UTLS) and their impact on its radiative budget requires accurate measurements. The composition of the UTLS is governed by transport and chemistry of stratospheric and tropospheric constituents, such as chlorine, nitrogen oxide and sulfur compounds. The Atmospheric chemical Ionization Mass Spectrometer AIMS has been developed to accurately measure a set of these constituents on aircraft by means of chemical ionization. Here we present a setup using SF5− reagent ions for the simultaneous measurement of trace gas concentrations of HCl, HNO3 and SO2 in the  pptv to ppmv (10−12 to 10−6 mol mol−1) range with in-flight and online calibration called AIMS-TG (Atmospheric chemical Ionization Mass Spectrometer for measurements of trace gases). Part 1 of this paper (Kaufmann et al., 2016) reports on the UTLS water vapor measurements with the AIMS-H2O configuration. The instrument can be flexibly switched between two configurations depending on the scientific objective of the mission. For AIMS-TG, a custom-made gas discharge ion source has been developed for generation of reagent ions that selectively react with HCl, HNO3, SO2 and HONO. HNO3 and HCl are routinely calibrated in-flight using permeation devices; SO2 is continuously calibrated during flight adding an isotopically labeled 34SO2 standard. In addition, we report on trace gas measurements of HONO, which is sensitive to the reaction with SF5−. The detection limit for the various trace gases is in the low 10 pptv range at a 1 s time resolution with an overall uncertainty of the measurement of the order of 20 %. AIMS has been integrated and successfully operated on the DLR research aircraft Falcon and HALO (High Altitude LOng range research aircraft). As an example, measurements conducted during the TACTS/ESMVal (Transport and Composition of the LMS/UT and Earth System Model Validation) mission with HALO in 2012 are presented, focusing on a classification of tropospheric and stratospheric influences in the UTLS region. The combination of AIMS measurements with other measurement techniques yields a comprehensive picture of the sulfur, chlorine and reactive nitrogen oxide budget in the UTLS. The different trace gases measured with AIMS exhibit the potential to gain a better understanding of the trace gas origin and variability at and near the tropopause.

scholarly journals A stratospheric intrusion at the subtropical jet over the Mediterranean Sea: air-borne remote sensing observations and model results

2012 ◽  
Vol 12 (3) ◽  
pp. 7793-7827
Author(s):  
K. Weigel ◽  
L. Hoffmann ◽  
G. Günther ◽  
F. Khosrawi ◽  
F. Olschewski ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Mediterranean Sea ◽  
Trace Gases ◽  
Analysis Data ◽  
Lagrangian Model ◽  
Mixing Ratios ◽  
Stratospheric Intrusion ◽  
Subtropical Jet ◽  
Research Aircraft ◽  
The Mediterranean

Abstract. Remote sensing measurements from the Cryogenic Infrared Spectrometers and Telescope for the Atmosphere – New Frontiers (CRISTA-NF) during a flight on 29 July 2006 are presented. This flight is part of the AMMA-SCOUT-O3 measurement campaign, where CRISTA-NF was deployed on the high-flying research aircraft M55-Geophysica. The flight path was located over Italy and the Mediterranean Sea and crossed over the subtropical jet twice. Measurements of temperature, and the volume mixing ratios of water vapor (H2O), ozone (O3), nitric acid (HNO3) and peroxyacetyl nitrate (PAN) are available with a vertical resolution of up to 500 m between about 6 to 21 km altitude. CRISTA-NF observes these trace gases simultaneously and provides a quasi-2D view of the transition region between the troposphere and the stratosphere. The observation of these different trace gases allows to determine the origin of air masses in the stratosphere or troposphere. As expected, higher abundances are found where the main source of the trace gases is located: in the stratosphere for O3 and in the troposphere for H2O and PAN. Tracer-tracer correlations between O3 and PAN are used to identify mixed tropospheric and lowermost stratospheric air at the subtropical jet and around the thermal tropopause north of the jet. An intrusion of stratospheric air into the troposphere associated with the subtropical jet is found in the CRISTA-NF observations. The observations indicate that the intrusion is connected to a tropopause fold which is not resolved in the ECMWF analysis data. The intrusion was reproduced in a simulation with the Chemical Lagrangian Model of the Stratosphere (CLaMS). This work discusses the nature of the observed processes at the subtropical jet based on the CRISTA-NF observations and the CLaMS simulation.

scholarly journals Seasonal cycles and variability of O<sub>3</sub> and H<sub>2</sub>O in the UT/LMS during SPURT

2005 ◽  
Vol 5 (4) ◽  
pp. 7247-7282
Author(s):  
M. Krebsbach ◽  
C. Schiller ◽  
D. Brunner ◽  
G. Günther ◽  
M. I. Hegglin ◽  
...  
Keyword(s):  
Trace Gases ◽  
Distribution Functions ◽  
Trace Gas ◽  
Large Set ◽  
Transport Barrier ◽  
Mixing Ratios ◽  
Tropical Tropopause ◽  
Time Period ◽  
Data Coverage

Abstract. Airborne high resolution in situ measurements of a large set of trace gases including ozone (O3) and total water (H2O) in the upper troposphere and the lowermost stratosphere (UT/LMS) have been performed above Europe within the SPURT project. With its innovative campaign concept, SPURT provides an extensive data coverage of the UT/LMS in each season within the time period between November 2001 and July 2003. Ozone volume mixing ratios in the LMS show a distinct spring maximum and autumn minimum, whereas the O3 seasonal cycle in the UT is shifted by 2 to 3 month later towards the end of the year. The more variable H2O measurements reveal a maximum during spring/summer and a minimum during autumn/winter with no phase shift between the two atmospheric compartments. For a comprehensive insight into trace gas composition and variability in the UT/LMS several statistical methods are applied using chemical, thermal and dynamical vertical coordinates. In particular, 2-dimensional probability distribution functions serve as a tool to transform localised aircraft data to a more comprehensive view of the probed atmospheric region. It appears that both trace gases, O3 and H2O, reveal the most compact arrangement and are best correlated in the view of potential vorticity (PV) and distance to the local tropopause, indicating an advanced mixing state on these surfaces. Thus, strong gradients of PV seem to act as a transport barrier both in the vertical and the horizontal direction. The alignment of trace gas isopleths reflects the existence of a year-round extra-tropical tropopause transition layer. The SPURT measurements reveal that this layer is mainly affected by stratospheric air during winter/spring and by tropospheric air during autumn/summer. Mixing entropy values for O3 and H2O in the LMS appear to be maximal during spring and summer, respectively, indicating highest variability of these trace gases during the respective seasons.

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