scholarly journals Characterisation of the filter inlet system on the BAE-146 research aircraft and its use for size resolved aerosol composition measurements

2019 ◽  
Author(s):  
Alberto Sanchez-Marroquin ◽  
Duncan H. P. Hedges ◽  
Matthew Hiscock ◽  
Simon T. Parker ◽  
Philip D. Rosenberg ◽  
...  
Keyword(s):  
Operating Conditions ◽  
Chemical Information ◽  
Atmospheric Measurements ◽  
Spectroscopy Analysis ◽  
Aerosol Composition ◽  
Inlet System ◽  
Particle Measurements ◽  
Coarse Mode ◽  
Peak Enhancement ◽  
Research Aircraft

Abstract. Atmospheric aerosol particles are important for our planet’s climate because they interact with radiation and clouds. Hence, having characterised methods to collect aerosol from aircraft for detailed offline analysis are valuable. However, collecting aerosol, particularly coarse mode aerosol, onto substrates from a fast moving aircraft is challenging and can result in both losses and enhancement in aerosol. Here we present the characterisation of an inlet system designed for collection of aerosol onto filters on board the UK’s BAe 146 Facility for Airborne Atmospheric Measurements (FAAM) research aircraft. We also present an offline Scanning Electron Microscopy (SEM) technique for quantifying both the size distribution and size resolved composition of the collected aerosol. We use this SEM technique in parallel with online underwing optical probes in order to experimentally characterise the efficiency of the inlet system. We find that the coarse mode aerosol is sub-isokinetically enhanced, with a peak enhancement at around 10 μm up to a factor of three under typical operating conditions. Calculations show that the efficiency of collection then decreases rapidly at larger sizes. In order to minimise the isokinetic enhancement of coarse mode aerosol we recommend sampling with total flow rates above 50 L min−1; operating the inlet with the bypass fully open helps achieve this by increasing the flow rate through the inlet nozzle. With the inlet characterised, we also present single particle chemical information obtained from X-ray spectroscopy analysis which allows us to group the particles into composition categories. Our intention is to use the composition information in parallel with filter based ice nucleating particle measurements in order to correlate composition and ice nucleating particle concentrations.

scholarly journals Characterisation of the filter inlet system on the FAAM BAe-146 research aircraft and its use for size-resolved aerosol composition measurements

2019 ◽  
Vol 12 (11) ◽  
pp. 5741-5763 ◽  
Author(s):  
Alberto Sanchez-Marroquin ◽  
Duncan H. P. Hedges ◽  
Matthew Hiscock ◽  
Simon T. Parker ◽  
Philip D. Rosenberg ◽  
...  
Keyword(s):  
Operating Conditions ◽  
Chemical Information ◽  
Atmospheric Measurements ◽  
Spectroscopy Analysis ◽  
Aerosol Composition ◽  
Inlet System ◽  
X Ray ◽  
Coarse Mode ◽  
Peak Enhancement ◽  
Research Aircraft

Abstract. Atmospheric aerosol particles are important for our planet's climate because they interact with radiation and clouds. Hence, having characterised methods to collect aerosol from aircraft for detailed offline analysis are valuable. However, collecting aerosol, particularly coarse-mode aerosol, onto substrates from a fast-moving aircraft is challenging and can result in both losses and enhancement in particles. Here we present the characterisation of an inlet system designed for collection of aerosol onto filters on board the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146-301 Atmospheric Research Aircraft. We also present an offline scanning electron microscopy (SEM) technique for quantifying both the size distribution and size-resolved composition of the collected aerosol. We use this SEM technique in parallel with online underwing optical probes in order to experimentally characterise the efficiency of the inlet system. We find that the coarse-mode aerosol is sub-isokinetically enhanced, with a peak enhancement at around 10 µm up to a factor of 2 under recommended operating conditions. Calculations show that the efficiency of collection then decreases rapidly at larger sizes. In order to minimise the isokinetic enhancement of coarse-mode aerosol, we recommend sampling with total flow rates above 50 L min−1; operating the inlet with the bypass fully open helps achieve this by increasing the flow rate through the inlet nozzle. With the inlet characterised, we also present single-particle chemical information obtained from X-ray spectroscopy analysis, which allows us to group the particles into composition categories.

scholarly journals Aerosol chemical and optical properties over the Paris area within ESQUIF project

2006 ◽  
Vol 6 (11) ◽  
pp. 3257-3280 ◽  
Author(s):  
A. Hodzic ◽  
R. Vautard ◽  
P. Chazette ◽  
L. Menut ◽  
B. Bessagnet
Keyword(s):  
Optical Properties ◽  
Secondary Organic Aerosols ◽  
Organic Aerosols ◽  
Dust Particles ◽  
Aerosol Size Distribution ◽  
Aerosol Composition ◽  
Aerosol Mass ◽  
Coarse Mode ◽  
Paris Area ◽  
Flight Trajectories

Abstract. Aerosol chemical and optical properties are extensively investigated for the first time over the Paris Basin in July 2000 within the ESQUIF project. The measurement campaign offers an exceptional framework to evaluate the performances of the chemistry-transport model CHIMERE in simulating concentrations of gaseous and aerosol pollutants, as well as the aerosol-size distribution and composition in polluted urban environments against ground-based and airborne measurements. A detailed comparison of measured and simulated variables during the second half of July with particular focus on 19 and 31 pollution episodes reveals an overall good agreement for gas-species and aerosol components both at the ground level and along flight trajectories, and the absence of systematic biases in simulated meteorological variables such as wind speed, relative humidity and boundary layer height as computed by the MM5 model. A good consistency in ozone and NO concentrations demonstrates the ability of the model to reproduce the plume structure and location fairly well both on 19 and 31 July, despite an underestimation of the amplitude of ozone concentrations on 31 July. The spatial and vertical aerosol distributions are also examined by comparing simulated and observed lidar vertical profiles along flight trajectories on 31 July and confirm the model capacity to simulate the plume characteristics. The comparison of observed and modeled aerosol components in the southwest suburb of Paris during the second half of July indicates that the aerosol composition is rather correctly reproduced, although the total aerosol mass is underestimated by about 20%. The simulated Parisian aerosol is dominated by primary particulate matter that accounts for anthropogenic and biogenic primary particles (40%), and inorganic aerosol fraction (40%) including nitrate (8%), sulfate (22%) and ammonium (10%). The secondary organic aerosols (SOA) represent 12% of the total aerosol mass, while the mineral dust accounts for 8%. The comparison demonstrates the absence of systematic errors in the simulated sulfate, ammonium and nitrates total concentrations. However, for nitrates the observed partition between fine and coarse mode is not reproduced. In CHIMERE there is a clear lack of coarse-mode nitrates. This calls for additional parameterizations in order to account for the heterogeneous formation of nitrate onto dust particles. Larger discrepancies are obtained for the secondary organic aerosols due to both inconsistencies in the SOA formation processes in the model leading to an underestimation of their mass and large uncertainties in the determination of the measured aerosol organic fraction. The observed mass distribution of aerosols is not well reproduced, although no clear explanation can be given.

scholarly journals On the vertical distribution of smoke in the Amazonian atmosphere during the dry season

2016 ◽  
Vol 16 (4) ◽  
pp. 2155-2174 ◽  
Author(s):  
Franco Marenco ◽  
Ben Johnson ◽  
Justin M. Langridge ◽  
Jane Mulcahy ◽  
Angela Benedetti ◽  
...  
Keyword(s):  
Vertical Structure ◽  
Atmospheric Measurements ◽  
Extinction Coefficients ◽  
Smoke Plumes ◽  
Model Predictions ◽  
Research Aircraft ◽  
The Vertical Distribution ◽  
Lidar Observations ◽  
Aerosol Extinction Coefficient ◽  
Assimilation System

Abstract. Lidar observations of smoke aerosols have been analysed from six flights of the Facility for Airborne Atmospheric Measurements BAe-146 research aircraft over Brazil during the biomass burning season (September 2012). A large aerosol optical depth (AOD) was observed, typically ranging 0.4–0.9, along with a typical aerosol extinction coefficient of 100–400 Mm−1. The data highlight the persistent and widespread nature of the Amazonian haze, which had a consistent vertical structure, observed over a large distance ( ∼ 2200 km) during a period of 14 days. Aerosols were found near the surface; but the larger aerosol load was typically found in elevated layers that extended from 1–1.5 to 4–6 km. The measurements have been compared to model predictions with the Met Office Unified Model (MetUM) and the ECMWF-MACC model. The MetUM generally reproduced the vertical structure of the Amazonian haze observed with the lidar. The ECMWF-MACC model was also able to reproduce the general features of smoke plumes albeit with a small overestimation of the AOD. The models did not always capture localised features such as (i) smoke plumes originating from individual fires, and (ii) aerosols in the vicinity of clouds. In both these circumstances, peak extinction coefficients of the order of 1000–1500 Mm−1 and AODs as large as 1–1.8 were encountered, but these features were either underestimated or not captured in the model predictions. Smoke injection heights derived from the Global Fire Assimilation System (GFAS) for the region are compatible with the general height of the aerosol layers.

scholarly journals Chemical and physical characteristics of aerosol particles at a remote coastal location, Mace Head, Ireland, during NAMBLEX

2006 ◽  
Vol 6 (11) ◽  
pp. 3289-3301 ◽  
Author(s):  
H. Coe ◽  
J. D. Allan ◽  
M. R. Alfarra ◽  
K. N. Bower ◽  
M. J. Flynn ◽  
...  
Keyword(s):  
Surf Zone ◽  
Organic Aerosol ◽  
Sea Salt ◽  
Research Station ◽  
Aerosol Composition ◽  
Gaseous Species ◽  
Accumulation Mode ◽  
Coarse Mode ◽  
Wide Range ◽  
Loss Rates

Abstract. A suite of aerosol physical and chemical measurements were made at the Mace Head Atmospheric Research Station, Co. Galway, Ireland, a coastal site on the eastern seaboard of the north Atlantic Ocean during NAMBLEX. The data have been used in this paper to show that over a wide range of aerosol sizes there is no impact of the inter-tidal zone or the surf zone on measurements made at 7 m above ground level or higher. During the measurement period a range of air mass types were observed. During anticyclonic periods and conditions of continental outflow Aitken and accumulation mode were enhanced by a factor of 5 compared to the marine sector, whilst coarse mode particles were enhanced during westerly conditions. Baseline marine conditions were rarely met at Mace Head during NAMBLEX and high wind speeds were observed for brief periods only. The NAMBLEX experiment focussed on a detailed assessment of photochemistry in the marine environment, investigating the linkage between the HOx and the halogen radical cycles. Heterogeneous losses are important in both these cycles. In this paper loss rates of gaseous species to aerosol surfaces were calculated for a range of uptake coefficients. Even when the accommodation coefficient is unity, lifetimes due to heterogeneous loss of less than 10 s were never observed and rarely were they less than 500 s. Diffusional limitation to mass transfer is important in most conditions as the coarse mode is always significant. We calculate a minimum overestimate of 50% in the loss rate if this is neglected and so it should always be considered when calculating loss rates of gaseous species to particle surfaces. HO2 and HOI have accommodation coefficients of around 0.03 and hence we calculate lifetimes due to loss to particle surfaces of 2000 s or greater under the conditions experienced during NAMBLEX. Aerosol composition data collected during this experiment provide representative information on the input aerosol characteristics to western Europe. During NAMBLEX the submicron aerosol was predominately acidified sulphate and organic material, which was most likely internally mixed. The remaining accumulation mode aerosol was sea salt. The organic and sulphate fractions were approximately equally important, though the mass ratio varies considerably between air masses. Mass spectral fingerprints of the organic fraction in polluted conditions are similar to those observed at other locations that are characterised by aged continental aerosol. In marine conditions, the background input of both sulphate and organic aerosol into Europe was observed to be between 0.5 and 1 µg m−3. Key differences in the mass spectra were observed during the few clean periods but were insufficient to ascertain whether these changes reflect differences in the source fingerprint of the organic aerosol. The coarse mode was composed of sea salt and showed significant displacement of chloride by nitrate and to a lesser extent sulphate in polluted conditions.

scholarly journals Observations on aerosol optical properties and scavenging during cloud events

2020 ◽  
Author(s):  
Antti Ruuskanen ◽  
Sami Romakkaniemi ◽  
Harri Kokkola ◽  
Antti Arola ◽  
Santtu Mikkonen ◽  
...  
Keyword(s):  
Large Scale ◽  
Aerosol Composition ◽  
Cloud Droplets ◽  
Inlet System ◽  
Scattering Coefficients ◽  
Stratus Clouds ◽  
Absorbing Material ◽  
Scattering Material ◽  
Cloud Scavenging ◽  
Increasing Temperature

Abstract. Long term statistics of atmospheric aerosol and especially cloud scavenging were studied at the Puijo measurement station in Kuopio, Finland, during October 2010–November 2014. Aerosol size distributions, scattering coefficients at three different wavelengths (450 nm, 550 nm, and 700 nm), and absorption coefficient at wavelength 637 nm were measured with a special inlet system to sample interstitial and total aerosol in clouds. On average, accumulation mode particle concentration was found to be temperature dependent with lowest average concentrations of 200 cm−3 around 0 °C increasing to more than 800 cm−3 for temperatures higher than 20 °C. From the in-cloud measurements, both scattering and absorbing material scavenging efficiencies were observed to have slightly increasing temperature dependence. At 0 °C the efficiencies of scattering and absorbing matter were 0.85 and 0.55 with slopes of 0.005 °C−1 and 0.003 °C−1, respectively. Additionally, scavenging efficiencies were studied as a function of the diameter at which half of the particles are activated into cloud droplets. This analysis indicated that the is a higher fraction of absorbing material, typically black carbon, in smaller sizes so that at least 20–30 % of interstitial particles within clouds consist of absorbing material. In addition, the PM1-inlet revealed that approximately 20 % of absorbing material was observed to reside in particles with ambient diameter larger than ~ 1 µm at relative humidity below 90 %. Similarly, 40 % of scattering material was seen to be in particles larger than 1 µm. Altogether, this dataset provides information on size dependent aerosol composition that can be applied in evaluating how well large-scale aerosol models reproduce aerosol composition, especially with respect to scavenging in stratus clouds.

scholarly journals Aerosol chemical and optical properties over the Paris area within ESQUIF project

2006 ◽  
Vol 6 (1) ◽  
pp. 401-454 ◽  
Author(s):  
A. Hodzic ◽  
R. Vautard ◽  
P. Chazette ◽  
L. Menut ◽  
B. Bessagnet
Keyword(s):  
Optical Properties ◽  
Secondary Organic Aerosols ◽  
Organic Aerosols ◽  
Dust Particles ◽  
Aerosol Size Distribution ◽  
Aerosol Composition ◽  
Aerosol Mass ◽  
Coarse Mode ◽  
Paris Area ◽  
Flight Trajectories

Abstract. Aerosol chemical and optical properties are extensively investigated for the first time over the Paris Basin in July 2000 within the ESQUIF project. The measurement campaign offers an exceptional framework to evaluate the performances of the chemistry-transport model CHIMERE in simulating concentrations of gaseous and aerosol pollutants, as well as the aerosol-size distribution and composition in polluted urban environment against ground-based and airborne measurements. A detailed comparison of measured and simulated variables during the second half of July with particular focus on 19 and 31 pollution episodes reveals an overall good agreement for gas-species and aerosol components both at the ground level and along flight trajectories, and the absence of systematic biases in simulated meteorological variables such as wind speed, relative humidity and boundary layer height as computed by the MM5 model. A good consistency in ozone and NO concentrations demonstrates the ability of the model to reproduce fairly well the plume structure and location both on 19 and 31 July, despite an underestimation of the amplitude of ozone concentrations on 31 July. The spatial and vertical aerosol distributions are also examined by comparing simulated and observed lidar vertical profiles along flight trajectories on 31 July and confirmed the model capacity to simulate the plume characteristics. The comparison of observed and modeled aerosol components in the southwest suburb of Paris during the second half of July indicated that the aerosol composition is rather correctly reproduced, although the total aerosol mass is underestimated of about 20%. The simulated Parisian aerosol is dominated by primary particulate matter that accounts for anthropogenic and biogenic primary particles (40%) and inorganic aerosol fraction (40%) including nitrate (8%), sulfate (22%) and ammonium (10%). The secondary organic aerosols (SOA) represent 12% of the total aerosol mass, while the mineral dust accounts for 8%. The comparison demonstrated the absence of systematic errors in the simulated sulfate, ammonium and nitrates total concentrations. However for nitrates the observed partition between fine and coarse mode is not reproduced. In CHIMERE there is a clear lack of coarse-mode nitrates. This calls for additional parameterizations in order to account for the heterogeneous formation of nitrate onto dust particles. Larger discrepancies are obtained for the secondary organic aerosols due to both inconsistencies in the SOA formation processes in the model leading to an underestimation of their mass and large uncertainties in the determination of the measured aerosol organic fraction. The observed mass distribution of aerosols is not well reproduced, although no clear explanation can be given.

Validating snow surface radiative transfer models between 89 and 243GHz using airborne observations over Arctic tundra

2020 ◽  
Author(s):  
Kirsty Wivell ◽  
Melody Sandells ◽  
Nick Rutter ◽  
Stuart Fox ◽  
Chawn Harlow ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Weather Prediction ◽  
Arctic Tundra ◽  
Scanning System ◽  
Polar Regions ◽  
Atmospheric Measurements ◽  
Microphysical Properties ◽  
Snow Properties ◽  
Research Aircraft ◽  
Microwave Radiances

<p>Satellite microwave radiances in atmospheric sounding bands, such as the 183GHz water vapour band, are an important source of data for Numerical Weather Prediction. However, these observations are frequently discarded in polar regions as they are also sensitive to the surface, and there is large uncertainty in the background surface emissivity which depends on the microphysical properties of the snowpack. We evaluate simulations of brightness temperature and emissivity from the Snow Microwave Radiative Transfer (SMRT) model for Arctic tundra snow at frequencies between 89 and 243GHz to assess the potential of being able to assimilate observations at key sounding frequencies, such as 183GHz. In-situ measurements of the surface snowpack were collected for 36 snow pits in Trail Valley Creek, near Inuvik, Canada during the March 2018 Measurements of Arctic Cloud, Snow, and Sea Ice nearby the Marginal Ice Zone (MACSSIMIZE) campaign, a collaboration between the Met Office, Northumbria University, Edinburgh University and the Universite de Sherbrooke. These snowpack measurements provide realistic microphysical snow properties as input to SMRT. We present the evaluation of SMRT simulations against surface-based radiometer observations and airborne observations taken with the Microwave Airborne Radiometer Scanning System (MARSS) and International Submillimetre Airborne Radiometer (ISMAR) on the Facility for Airborne Atmospheric Measurements (FAAM) BAe 146 research aircraft.</p>

Fuel Cells for Aircraft Application

2009 ◽  
Author(s):  
Kaspar Andreas Friedrich ◽  
Josef Kallo ◽  
Johannes Schirmer
Keyword(s):  
Fuel Cell ◽  
Electrical Power ◽  
Cell System ◽  
Operating Conditions ◽  
Experimental Investigations ◽  
Fuel Cell System ◽  
System Architectures ◽  
Cell Systems ◽  
Research Aircraft ◽  
Aircraft Application

Although air transport is responsible for only about 2% of all anthropogenic CO2 emissions, the rapidly increasing volume of air traffic leads to a general concern about the environmental impact of aviation. Future aircraft generations have to face enhanced requirements concerning productivity, environmental compatibility and higher operational availability, thus effecting technical, operational and economical aspects of in-flight and on-ground power generation systems. Today’s development in aircraft architecture undergoes a trend to a “more electric aircraft” which is characterised by a higher proportion of electrical systems substituting hydraulically or pneumatically driven components, and, thus, increasing the amount of electrical power. Fuel cell systems in this context represent a promising solution regarding the enhancement of the energy efficiency for both cruise and ground operations. For several years the Institute of Technical Thermodynamics of the German Aerospace Center (Deutsches Zentrum fu¨r Luft- und Raumfahrt, DLR) in Stuttgart is engaged in the development of fuel cell systems for aircraft applications. The activities of DLR focus on: • Identification of fuel cell applications in aircraft in which the properties of fuel cell systems, namely high electric efficiency, low emissions and silent operation, are capitalized for the aircraft application. • Design and modeling of possible system designs. • Experimental investigations regarding specific aircraft relevant operating conditions. • Qualification of airworthy fuel cell systems. • Set up and full scale testing of fuel cell systems for application in research aircraft. In cooperation with Airbus several fuel cell applications within the aircraft for both ground and cruise operation could be identified. In consequence, fuel cell systems capable to support or even replace existing systems have been derived. In this context, the provision of inert gas for the jet fuel (kerosene) tank and electrical cabin power supply including water regeneration represent the most promising application fields. The contribution will present the state of development discussing the following points: • Modeling of different system architectures and evaluation of promising fuel cell technologies (PEFC vs. SOFC). • Experimental evaluation of fuel cell systems under relevant conditions (low-pressure, vibrations, reformate operation, etc.). • Fuel cell system demonstrator Hyfish (hydrogen powered model aircraft). • Fuel cell test in DLR’s research aircraft ATRA (A320) including the test of an emergency system based on hydrogen and oxygen with 20 kW of electrical power. The fuel cell system was integrated into an A320 aircraft and tested up to a flight altitude of 25 000 feet under several acceleration and inclination conditions.

scholarly journals The development and evaluation of airborne in situ N<sub>2</sub>O and CH<sub>4</sub> sampling using a Quantum Cascade Laser Absorption Spectrometer (QCLAS)

2015 ◽  
Vol 8 (8) ◽  
pp. 8859-8902 ◽  
Author(s):  
J. R. Pitt ◽  
M. Le Breton ◽  
G. Allen ◽  
C. J. Percival ◽  
M. W. Gallagher ◽  
...  
Keyword(s):  
Quantum Cascade Laser ◽  
Ambient Pressure ◽  
Calibration Procedure ◽  
Atmospheric Measurements ◽  
Quantum Cascade ◽  
Laser Absorption ◽  
Influence Of Water ◽  
Research Aircraft ◽  
Potential Case ◽  
Absorption Spectrometer

Abstract. Spectroscopic measurements of atmospheric N2O and CH4 mole fractions were made on board the FAAM (Facility for Airborne Atmospheric Measurements) large Atmospheric Research Aircraft. We present details of the mid-IR Aerodyne Research Inc. Quantum Cascade Laser Absorption Spectrometer (QCLAS) employed, including its configuration for airborne sampling, and evaluate its performance over 17 flights conducted during summer 2014. Two different methods of correcting for the influence of water vapour on the spectroscopic retrievals are compared and evaluated. A new in-flight calibration procedure to account for the observed sensitivity of the instrument to ambient pressure changes is described, and its impact on instrument performance is assessed. Test flight data linking this sensitivity to changes in cabin pressure is presented. Total 1σ uncertainties of 1.81 ppb for CH4 and 0.35 ppb for N2O are derived. We report a mean difference in 1 Hz CH4 mole fraction of 2.05 ppb (1σ = 5.85 ppb) between in-flight measurements made using the QCLAS and simultaneous measurements using a previously characterised Los Gatos Research Fast Greenhouse Gas Analyser (FGGA). Finally, a potential case study for the estimation of a regional N2O flux using a mass balance technique is identified, and the method for calculating such an estimate is outlined.

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