A5051631899- Atmospheric chemistry and aerosols
- Atmospheric aerosols and clouds
- Air Quality and Health Impacts
- Atmospheric Ozone and Climate
- Atmospheric and Environmental Gas Dynamics
- Air Quality Monitoring and Forecasting
- Spectroscopy and Laser Applications
- Vehicle emissions and performance
- Fire effects on ecosystems
- Oil Spill Detection and Mitigation
- COVID-19 impact on air quality
- Toxic Organic Pollutants Impact
- Fire dynamics and safety research
- Thermochemical Biomass Conversion Processes
- Impact of Light on Environment and Health
- Energy and Environment Impacts
- Aeolian processes and effects
- Calibration and Measurement Techniques
- Environmental and biological studies
- Advanced Fiber Laser Technologies
- Remote Sensing in Agriculture
- Advanced Aircraft Design and Technologies
- Electrochemical sensors and biosensors
- Origins and Evolution of Life
- Mercury impact and mitigation studies
Met Office
2015-2025
University of Exeter
2020
Phillips Exeter Academy
2020
University of Cambridge
2004-2013
Cooperative Institute for Research in Environmental Sciences
2010-2013
University of Colorado Boulder
2011-2013
NOAA Earth System Research Laboratory
2011-2013
National Oceanic and Atmospheric Administration
2011-2012
Biomass burning (BB) contributes large amounts of black carbon (BC) and particulate organic matter (POM) to the atmosphere significantly earth’s radiation balance. BB particles can be a complicated optical system, with scattering absorption contributions from BC, internal mixtures BC POM, wavelength-dependent POM. Large POM also externally mixed. We report on unique ability multi-wavelength photo-acoustic measurements dry thermal-denuded deconstruct this system mixing. Optical Four Mile...
Abstract. The absorption Ångström exponent (AAE) of externally mixed black carbon (BCExt), or BC internally with non-absorbing material (BCInt), is often used to determine the contribution brown (BrC) light at short visible wavelengths. This attribution method contains assumptions uncertainties that have not been formally assessed. We show potential range AAE for BCExt (or BCInt) in atmosphere can reasonably lead +7% −22% uncertainty wavelengths derived from measurements made longer...
Abstract. Single-scattering albedo (SSA) and absorption Ångström exponent (AAE) are two critical parameters in determining the impact of absorbing aerosol on Earth's radiative balance. Aerosol emitted by biomass burning represent a significant fraction globally, but it remains difficult to accurately predict SSA AAE for aerosol. Black carbon (BC), brown (BrC), non-absorbing coatings all make substantial contributions coefficient cannot be directly predicted based fuel type because they...
Abstract. The representations of clouds, aerosols, and cloud–aerosol–radiation impacts remain some the largest uncertainties in climate change, limiting our ability to accurately reconstruct past predict future climate. south-east Atlantic is a region where high atmospheric aerosol loadings semi-permanent stratocumulus clouds are co-located, providing an optimum for studying full range aerosol–radiation aerosol–cloud interactions their perturbations Earth's radiation budget. While satellite...
This paper describes the design and performance of a photo-acoustic aerosol absorption spectrometer (PAS) built for operation on research aircraft platform. The PAS instrument is capable measuring dry at 659 nm, 532 404 enhancement due to coatings nm nm. measurement accuracy all channels < = 10% in flight 1 Hz sensitivities lie within range 0.5–1.5 Mm−1. measurements calibrated absorbing samples are shown be consistent with made by previous generation single channel instrument. Aircraft data...
Supercontinuum radiation sources are attractive for spectroscopic applications owing to their broad wavelength coverage, which enables spectral signatures of multiple species be detected simultaneously. Here we report the first use a supercontinuum source broadband trace gas detection using cavity enhanced absorption technique. Spectra were recorded at bandwidths up 100 nm, encompassing bands H(2)O, O(2) and O(2)-O(2). The same instrument was also used make quantitative measurements NO(2)...
Abstract. This paper presents a summary of the measurements made during heavily-instrumented Reactive Halogens in Marine Boundary Layer (RHaMBLe) coastal study Roscoff on North West coast France throughout September 2006. It was clearly demonstrated that iodine-mediated particle formation occurs, driven by daytime low tide emission molecular iodine, I2, macroalgal species fully or partially exposed receding waterline. Ultrafine concentrations strongly correlate with rapidly recycled reactive...
Atmospheric emissions of gas and particulate matter from a large ocean-going container vessel were sampled as it slowed switched high-sulfur to low-sulfur fuel transited into regulated coastal waters California. Reduction in emission factors (EFs) sulfur dioxide (SO2), matter, sulfate cloud condensation nuclei substantial (≥90%). EFs for organic decreased by 70%. Black carbon (BC) reduced 41%. When the measured reductions, brought about compliance with California quality regulation...
Abstract. The REgents PARk and Tower Environmental Experiment (REPARTEE) comprised two campaigns in London October 2006 October/November 2007. experiment design involved measurements at a heavily trafficked roadside site, urban background sites an elevated site 160–190 m above ground on the BT Tower, supplemented second campaign by Doppler lidar of atmospheric vertical structure. A wide range airborne particle physical metrics chemical composition were made as well considerable gas phase...
High-quality in situ observations of aerosol particle optical properties, namely extinction, scattering, and absorption, provide important information needed to constrain the role aerosols climate system. This paper outlines design performance an aircraft instrument utilizing cavity ringdown spectroscopy for measurement extinction. The 8-channel spectrometer measures extinction at multiple wavelengths (405, 532, 662 nm) relative humidities (e.g., 10%, 70%, 95%). Key characteristics include a...
Abstract. Traditional gas and particle phase chemical markers used to identify the presence of biomass burning (BB) emissions were measured for a large forest fire near Boulder, Colorado. Correlation organic matter mass spectroscopic m/z 60 with light absorption properties found no link at 532 nm, strong correlation 404 nm. Non-black carbon nm was well correlated ratio fractions particulate (POM) that (f60) 44 (f44). The f60 f44 did not fully explain variability in non-BC absorption, due...
Abstract. A wide range of globally significant biomass fuels were burned during the fourth Fire Lab at Missoula Experiment (FLAME-4). multi-channel photoacoustic absorption spectrometer (PAS) measured dry 405, 532, and 660 nm thermally denuded (250 °C) 405 nm. Absorption coefficients broken into contributions from black carbon (BC), brown (BrC), lensing following three different methodologies, with one extreme being a method that assumes thermal denuder effectively removes organics other...
Abstract. Seasonal biomass burning (BB) from June to October in central and southern Africa leads absorbing aerosols being transported over the South Atlantic Ocean every year contributes significantly regional climate forcing. The vertical distribution of submicron their properties were characterized remote southeast Atlantic, using airborne situ measurements made during CLoud-Aerosol-Radiation Interactions Forcing for Year 2017 (CLARIFY-2017) campaign. BB emitted flaming-controlled fires...
Abstract. The optical properties of black carbon (BC) are a major source uncertainty in regional and global climate studies. In the past, detailed investigation BC absorption has been hampered by systematic biases measurement instrumentation. We present airborne measurements aerosol microphysical highly aged biomass burning plumes measured 4–8 d from their over southeast Atlantic Ocean during CLARIFY-2017, using suite novel photoacoustic spectrometers to measure at 405, 514, 655 nm...
Abstract Biomass burning (BB) produces large quantities of carbonaceous aerosol (black carbon and organic aerosol, BC OA, respectively), which significantly degrade air quality impact climate. absorbs radiation, warming the atmosphere, while OA typically scatters leading to cooling. However, some termed brown (BrC), also visible near UV radiation; although, its properties are not well constrained. We explore three aircraft campaigns from important BB regions with different dominant fuel fire...
A broadband absorption spectrometer has been developed for highly sensitive and target-selective in situ trace gas measurements. The instrument employs two distinct modes of operation: (i) cavity enhanced spectroscopy (BBCEAS) is used to quantify the concentration gases sample mixtures from their characteristic features, (ii) periodic measurements mirrors' reflectivity are made using step-scan phase shift ringdown (PSCRDS). latter PSCRDS method provides a stand-alone alternative more usual...
A compact and low power detector has been developed for the in situ measurement of atmospheric NO(2) using broadband cavity enhanced absorption spectroscopy. Absorption by O(2)-O(2) collisional pair was used to determine mirror reflectivity, thus enabling retrieval absolute absorber concentrations differential spectral fitting techniques. Quantitative amounts ambient (between 3 32 parts per billion) were retrieved from spectra recorded presence aerosol with statistical uncertainties...
Abstract. A three channel broadband cavity enhanced absorption spectroscopy (BBCEAS) instrument has been developed for airborne measurements of atmospheric trace gases involved in night-time oxidation chemistry and air quality. The was deployed on board the Facility Airborne Atmospheric Measurements BAe 146-301 research aircraft during Role Nighttime Chemistry Controlling Oxidising Capacity Atmosphere (RONOCO) measurement campaigns between December 2009 January 2011. In its present...
Laboratory experiments were conducted to assess the suitability of photoacoustic spectroscopy (PAS) for aerosol absorption measurement at high relative humidity (RH). Initial characterized PAS sensitivity that increased strongly by ∼1.25 between dry conditions and 90% RH. Correction procedures validated measuring RH-independent hydrophobic absorbing particles. Absorption measured a range hygroscopic particles, including different morphologies, hygroscopicities, entities, showed strong low...
During the Deepwater Horizon ( DWH ) oil spill, a wide range of gas and aerosol species were measured from an aircraft around, downwind, away site. Additional hydrocarbon measurements made ships in vicinity. Aerosol particles respirable sizes on occasions significant air quality issue for populated areas along Gulf Coast. Yields organic emission factors other atmospheric pollutants derived sources recovery, cleanup efforts. Evaporation subsequent secondary chemistry produced particulate...
Airborne measurements of sub‐micron aerosol and trace gases downwind Los Angeles are used to investigate the influence aging on properties relevant climate forcing visibility. The analysis focuses plume, which in addition strong urban emissions is influenced by local agricultural emissions. Secondary organic formation repartitioning semi‐volatile ammonium nitrate were identified as key factors controlling optical behavior observed. For one case study, contributed up 50% total dry extinction....
Abstract. Biases in absorption coefficients measured using a filter-based photometer (Tricolor Absorption Photometer, or TAP) at wavelengths of 467, 528 and 652 nm are evaluated by comparing to measurements made photoacoustic spectroscopy (PAS). We report comparisons for ambient sampling covering range aerosol types including urban, fresh biomass burning aged burning. Data also used evaluate the performance three different TAP correction schemes. found that were well correlated, but...
Abstract. In recent years, photoacoustic spectroscopy has emerged as an invaluable tool for the accurate measurement of light absorption by atmospheric aerosol. Photoacoustic instruments require calibration, which can be achieved measuring signal generated known quantities gaseous ozone. Recent work questioned validity this approach at short visible wavelengths (404 nm), indicating systematic calibration errors order a factor 2. We revisit result and test ozone method using suite multipass...