A5088446807- Atmospheric chemistry and aerosols
- Atmospheric Ozone and Climate
- Atmospheric and Environmental Gas Dynamics
- Arctic and Antarctic ice dynamics
- Cryospheric studies and observations
- Mercury impact and mitigation studies
- Atmospheric aerosols and clouds
- Toxic Organic Pollutants Impact
- Air Quality and Health Impacts
- Geology and Paleoclimatology Research
- Icing and De-icing Technologies
- Methane Hydrates and Related Phenomena
- Climate change and permafrost
- Freezing and Crystallization Processes
- Ocean Acidification Effects and Responses
- Climate variability and models
- Smart Materials for Construction
- Plant responses to elevated CO2
- Meteorological Phenomena and Simulations
- Solar and Space Plasma Dynamics
- nanoparticles nucleation surface interactions
- Water Quality Monitoring and Analysis
- Scientific Research and Discoveries
- Survey Methodology and Nonresponse
- Coal Properties and Utilization
Natural Environment Research Council
2015-2025
British Antarctic Survey
2016-2025
Google (United States)
2024
University of Cambridge
2006-2020
UK Research and Innovation
2020
National Centre for Atmospheric Science
2005-2014
Bridge University
2010
University of Leeds
2009
Abstract. Global models of atmospheric mercury generally assume that gas-phase OH and ozone are the main oxidants converting Hg0 to HgII thus driving deposition ecosystems. However, thermodynamic considerations argue against importance these reactions. We demonstrate here viability atomic bromine (Br) as an alternative oxidant. conduct a global 3-D simulation with GEOS-Chem model assuming Br be sole oxidant (Hg + model) compare previous version OH/O3 model). specify concentration fields...
Snow lying on sea ice could be a potentially important source of salt aerosol, as small snow particles, rich in salts, can easily lifted into the air though blowing‐snow events. Using measured distribution salinity Antarctic and blowing sublimation parameterization, we derive method for estimating aerosol production, bromine release, during Compared with production rates from open ocean, find that rate more than an order magnitude larger per unit area under typical weather conditions. The...
Abstract. We present a new model for the global tropospheric chemistry of inorganic bromine (Bry) coupled to oxidant-aerosol in GEOS-Chem chemical transport (CTM). Sources Bry include debromination sea-salt aerosol, photolysis and oxidation short-lived bromocarbons, from stratosphere. Comparison GOME-2 satellite climatology BrO columns shows that can reproduce observed increase with latitude, northern mid-latitudes maximum winter, Arctic spring. This successful simulation is contingent on...
Abstract. The role of ice in the formation chemically active halogens environment requires a full understanding because its atmospheric chemistry, including controlling regional oxidizing capacity specific situations. In particular, and snow are important for facilitating multiphase oxidative chemistry as media upon which marine algae live. This paper reviews nature environmental substrates that participate halogen describes reactions occur on such substrates, presents field evidence...
An off‐line three‐dimensional tropospheric chemical transport model, parallel–Tropospheric Off‐Line Model of Chemistry and Transport ( p ‐TOMCAT), has been extended by incorporating a detailed bromine chemistry scheme that contains gas‐phase reactions heterogeneous on both cloud particles background aerosols. Bromine emission from bromocarbon photo‐oxidation sea‐salt depletion removal through dry wet deposition are included. Using this ozone budgets studied. The zonal mean the inorganic...
We calculate the global mean atmospheric lifetime of elemental mercury (Hg 0 ) against oxidation by atomic bromine (Br) in troposphere combining recent kinetic data for Hg‐Br system with modeled concentrations tropospheric Br. obtain a 0.5–1.7 years based on range data, implying that Hg Br is major, and possibly dominant, sink . Most takes place middle upper troposphere, where are high cold temperatures suppress thermal decomposition HgBr intermediate. This mechanism consistent observations,...
Abstract. Measurements from the GOME-2 satellite instrument have been analyzed for tropospheric BrO using a residual technique that combines measured columns and estimates of stratospheric content climatological approach driven by O3 NO2 observations. Comparisons between results vertical derived correlative ground-based SCIAMACHY nadir observations, present good level consistency. We show adopted enables separation fractions total allows quantitative study plumes in polar regions. While some...
A global three‐dimensional chemical transport model has been used to simulate atmospheric bromoform using a variety of prescribed surface emission scenarios and simple chemistry scheme. Model simulations indicate that emissions calculated previously top‐down methods are too low, likely be significantly larger than suggested in the World Meteorological Organization's reports on Scientific Assessment Ozone Depletion 1998 2002. Our suggest range 400–600 GgCHBr 3 /yr large proportion situated...
Abstract. In the last two decades, significant depletion of boundary layer ozone (ozone events, ODEs) has been observed in both Arctic and Antarctic spring. ODEs are attributed to catalytic destruction by bromine radicals (Br plus BrO), especially during explosion events (BEs), when high concentrations BrO periodically occur. However, neither exact source nor mechanism for sustaining is completely understood. Here, considering production sea salt aerosol from snow lying on ice blowing...
Abstract. Two consecutive cruises in the Weddell Sea, Antarctica, winter 2013 provided first direct observations of sea salt aerosol (SSA) production from blowing snow above ice, thereby validating a model hypothesis to account for time SSA maxima Antarctic. Blowing or drifting often leads increases during and after storms. For it is shown that on ice depleted sulfate relative sodium with respect seawater. Similar depletion bulk sized ∼0.3–6 µm evidence most originated not open ocean leads,...
Abstract. Current understanding of mercury (Hg) behavior in the atmosphere contains significant gaps. Some key characteristics Hg processes, including anthropogenic and geogenic emissions, atmospheric chemistry, air–surface exchange, are still poorly known. This study provides a complex analysis processes governing fate involving both measured data from ground-based sites simulation results chemical transport models. A variety long-term measurements gaseous elemental (GEM) reactive (RM)...
Abstract. Lightning is one of the major natural sources NOx in atmosphere. A suite time slice experiments using a stratosphere-resolving configuration Unified Model (UM), containing United Kingdom Chemistry and Aerosols sub-model (UKCA), has been performed to investigate impact climate change on emissions from lightning (LNOx) highlight its critical impacts photochemical ozone production oxidising capacity troposphere. Two Representative Concentration Pathway (RCP) scenarios (RCP4.5 RCP8.5)...
Abstract. Mercury (Hg) is a worldwide contaminant that can cause adverse health effects to wildlife and humans. While atmospheric modeling traces the link from emissions deposition of Hg onto environmental surfaces, large uncertainties arise our incomplete understanding processes (oxidation pathways, deposition, re-emission). Atmospheric reactivity exacerbated in high latitudes there still much be learned polar regions terms processes. This paper provides synthesis monitoring data available...
Abstract The Arctic warms nearly four times faster than the global average, and aerosols play an increasingly important role in climate change. In Arctic, sea salt is a major aerosol component terms of mass concentration during winter spring. However, mechanisms production remain unclear. Sea are typically thought to be relatively large size but low number concentration, implying that their influence on cloud condensation nuclei population properties generally minor. Here we present...
Abstract Natural aerosols and their interactions with clouds remain an important uncertainty within climate models, especially at the poles. Here, we study behavior of sea salt (SSaer) in Arctic Antarctic 12 models from CMIP6. We investigate driving factors that control SSaer abundances show large differences based on choice source function, representation aerosol processes atmosphere. Close to poles, CMIP6 do not match observed seasonal cycles surface concentrations, likely due absence...
Abstract Multiple year‐round records of bulk and size‐segregated compositions aerosol were obtained at the coastal Dumont d'Urville (DDU) inland Concordia sites located in East Antarctica. They document sea‐salt load composition including, for first time Antarctica, bromide depletion relative to sodium with respect seawater. In parallel, measurements trapped mist chambers denuder tubes done investigate concentrations gaseous inorganic bromine species. These data are compared simulations an...
Abstract. Oceanic emissions of halogenated very short-lived substances (VSLS) are expected to contribute significantly the stratospheric halogen loading and therefore ozone depletion. The amount VSLS transported into stratosphere is estimated based on in-situ observations around tropical tropopause layer (TTL) modeling studies which mostly use prescribed global emission scenarios reproduce observed atmospheric concentrations. In addition upper-air measurements, direct oceanic available along...
Abstract Sea ice is a reflection of, and feedback on, the Earth's climate. We explore here, using global atmospheric chemistry‐transport model, use of sea salt in Antarctic cores to obtain continuous long‐term, regionally integrated records past extent, synchronous with core The model includes production, transport, deposition aerosol from open ocean “blowing snow” on ice. Under current climate conditions, we find that meteorology, not dominant control concentration reaching coastal...
Abstract. We use observations of the absorption properties black carbon and non-black impurities in near-surface snow collected near research stations at South Pole Dome C, Antarctica, Summit, Greenland, combined with a snowpack actinic flux parameterization to estimate vertical profile e-folding depth ultraviolet/near-visible (UV/near-vis) each location. have developed simple broadly applicable calculate wavelength dependent that can be easily integrated into large-scale (e.g., 3-D) models...
Abstract. Growing evidence suggests that the sea ice surface is an important source of salt aerosol and this has significant implications for polar climate atmospheric chemistry. It also potential to use core records as proxies past extent. To explore possibility in Arctic region, we a chemical transport model track emission, transport, deposition from both open ocean ice, allowing us assess relative importance each. Our results confirm (SISS) winter burden. For first time, explicitly...
Abstract. Blowing snow over sea ice has been proposed as a significant source of salt aerosol (SSA) (Yang et al., 2008). In this study, using salinity data and blowing particle measurements collected in the Weddell Sea zone (SIZ) during winter cruise, we perform comprehensive model–data comparison with aim validating parameterizations. Additionally, investigate possible physical mechanisms involved SSA production from snow. A global chemical transport model, p-TOMCAT, is used to examine...
Abstract. An environmental scanning electron microscope (ESEM) was used for the first time to obtain well-resolved images, in both temporal and spatial dimensions, of lab-prepared frost flowers (FFs) under evaporation within chamber temperature range from −5 −18 °C pressures above 500 Pa. Our shows temperature-dependent NaCl speciation: brine covering ice observed at all conditions, whereas crystals were formed temperatures below −10 as oversaturation achieved. Finger-like structures covered...
Mercury emissions from biomass burning are not well characterized and can differ significantly year to year. This study utilizes three recent inventories (FINNv1.0, GFEDv3.1, GFASv1.0) the global Hg chemistry model, ECHMERIT, investigate annual variation of emissions, geographical distribution magnitude resulting deposition fluxes. The roles Hg/CO enhancement ratio, emission plume injection height, Hg(g)0 oxidation mechanism lifetime, inventory chosen, uncertainties with each were...
Abstract Ozone depletion events in the polar troposphere have been linked to extremely high concentrations of bromine, known as bromine explosion (BEE). However, optimum meteorological conditions for occurrence these remain uncertain. On 4–5 April 2011, a combination both blowing snow and stable shallow boundary layer was observed during BEE at Eureka, Canada (86.4°W, 80.1°N). Measurements made by Multi‐Axis Differential Optical Absorption Spectroscopy spectrometer were used retrieve BrO...