A5003739704- Atmospheric Ozone and Climate
- Atmospheric and Environmental Gas Dynamics
- Atmospheric chemistry and aerosols
- Ocean Acidification Effects and Responses
- Air Quality Monitoring and Forecasting
- Methane Hydrates and Related Phenomena
- Climate variability and models
- Air Quality and Health Impacts
- Mercury impact and mitigation studies
- Climate Change and Health Impacts
- Marine and coastal ecosystems
- Meteorological Phenomena and Simulations
- Hydrocarbon exploration and reservoir analysis
- Vehicle emissions and performance
- Climate Change and Geoengineering
- Water Quality Monitoring and Analysis
- Toxic Organic Pollutants Impact
- Environmental Policies and Emissions
- Spectroscopy and Laser Applications
- Atmospheric aerosols and clouds
- Ionosphere and magnetosphere dynamics
- Advanced Clustering Algorithms Research
- Tropical and Extratropical Cyclones Research
- Polar Research and Ecology
- Geological and Geophysical Studies
Lancaster University
2016-2025
University of Leeds
2009-2016
National Centre for Atmospheric Science
2010-2014
Abstract Atmospheric methane grew very rapidly in 2014 (12.7 ± 0.5 ppb/year), 2015 (10.1 0.7 2016 (7.0 and 2017 (7.7 at rates not observed since the 1980s. The increase burden began 2007, with mean global mole fraction remote surface background air rising from about 1,775 ppb 2006 to 1,850 2017. Simultaneously 13 C/ 12 C isotopic ratio (expressed as δ CH4 ) has shifted, now trending negative for more than a decade. causes of methane's recent are therefore either change relative proportions...
Abstract It is well established that anthropogenic chlorine-containing chemicals contribute to ozone layer depletion. The successful implementation of the Montreal Protocol has led reductions in atmospheric concentration many ozone-depleting gases, such as chlorofluorocarbons. As a consequence, stratospheric chlorine levels are declining and projected return observed pre-1980 later this century. However, recent observations show dichloromethane—an gas not controlled by Protocol—is increasing...
Abstract We use height‐resolved and total column satellite observations 3‐D chemical transport model simulations to study stratospheric ozone variations during 1998–2017 as ozone‐depleting substances decline. In 2017 extrapolar lower displayed a strong positive anomaly following much values in 2016. This points large interannual variability rather than an ongoing downward trend, reported recently by Ball et al. (2018, https://doi.org/10.5194/acp‐18‐1379‐2018 ). The observed are well captured...
Our understanding of the processes that control burden and budget tropospheric ozone has changed dramatically over last 60 years. Models are key tools used to understand these changes, underscore there many important in controlling budget. In this critical review, we assess our evolving processes, both physical chemical. We review model simulations from International Global Atmospheric Chemistry Climate Model Intercomparison Project Modelling Initiative changes its 1850 2010. Analysis data...
The Antarctic ozone hole is decreasing in size but this recovery will be affected by atmospheric variability and any unexpected changes chlorinated source gas emissions. Here, using model simulations, we show that the largely cease to occur 2065 given compliance with Montreal Protocol. If unusual meteorology of 2002 repeated, an ozone-hole-free-year could as soon early 2020s some metrics. recently discovered increase CFC-11 emissions ~ 13 Gg yr-1 may delay recovery. So far impact on small,...
Abstract Observational evidence shows the ubiquitous presence of ocean-emitted short-lived halogens in global atmosphere 1–3 . Natural emissions these chemical compounds have been anthropogenically amplified since pre-industrial times 4–6 , while, addition, anthropogenic halocarbons are currently being emitted to 7,8 Despite their widespread distribution atmosphere, combined impact species on Earth’s radiative balance remains unknown. Here we show that exert a substantial indirect cooling...
Abstract Chlorine atoms (Cl) are highly reactive toward hydrocarbons in the Earth's troposphere, including greenhouse gas methane (CH 4 ). However, regional and global CH sink from Cl is poorly quantified as tropospheric concentrations ([Cl]) uncertain by ~2 orders of magnitude. Here we describe addition a detailed chlorine scheme to TOMCAT chemical transport model. The model includes several sources inorganic (Cl y ), (i) oxidation chlorocarbons natural 3 Cl, CHBr 2 BrCl, CHBrCl )...
Abstract. We have developed a detailed chemical scheme for the degradation of short-lived source gases bromoform (CHBr3) and dibromomethane (CH2Br2) implemented it in TOMCAT/SLIMCAT three-dimensional (3-D) transport model (CTM). The CTM has been used to predict distribution two (SGs) 11 their organic product (PGs). These first global calculations PGs show that abundance is small. longest lived are CBr2O CHBrO, but peak tropospheric relative surface volume mixing ratio (vmr) SGs less than 5%....
Abstract. The atmospheric methane (CH4) growth rate has varied considerably in recent decades. Unexplained renewed after 2006 followed 7 years of stagnation and coincided with an isotopic trend toward CH4 more depleted 13C, suggesting changes sources and/or sinks. Using surface observations both the relative change isotopologue ratio (δ13CH4) to constrain a global 3-D chemical transport model (CTM), we have performed synthesis inversion for source sink attribution. Our method extends on...
Very short-lived substances (VSLS), including dichloromethane (CH2Cl2), chloroform (CHCl3), perchloroethylene (C2Cl4), and 1,2-dichloroethane (C2H4Cl2), are a stratospheric chlorine source therefore contribute to ozone depletion. We quantify trends from these VSLS (VSLCltot) using chemical transport model atmospheric measurements, novel high-altitude aircraft data the NASA VIRGAS (2015) POSIDON (2016) missions. estimate VSLCltot increased 69 (±14) parts per trillion (ppt) Cl in 2000 111...
Abstract CH 4 is the most abundant reactive greenhouse gas and a complete understanding of its atmospheric fate needed to formulate mitigation policies. Current chemistry-climate models tend underestimate lifetime , suggesting uncertainties in sources sinks. Reactive halogens substantially perturb budget tropospheric OH, main loss. However, such an effect not considered existing climate projections burden radiative forcing. Here, we demonstrate that halogen chemistry increases global by 6–9%...
Abstract In contrast to the general stratospheric ozone recovery following international agreements, recent observations show an ongoing net depletion in tropical lower stratosphere (LS). This is thought be driven by dynamical transport accelerated global warming, while chemical processes have been considered unimportant. Here we use a chemistry–climate model demonstrate that halogenated ozone-depleting very short-lived substances (VSLS) chemistry may account for around quarter of observed...
Abstract. Emissions of halogenated very short-lived substances (VSLS) are poorly constrained. However, their inclusion in global models is required to simulate a realistic inorganic bromine (Bry) loading both the troposphere, where chemistry perturbs oxidising capacity, and stratosphere, it major sink for ozone (O3). We have performed simulations using 3-D chemical transport model (CTM) including three top-down single bottom-up derived emission inventory brominated VSLS bromoform (CHBr3)...
Abstract Following the eruption of Mount Pinatubo, satellite and in situ measurements showed a large enhancement stratospheric aerosol both hemispheres, but significant midlatitude column O 3 depletion was observed only north. We use three‐dimensional chemical transport model to determine mechanisms behind this hemispheric asymmetry. The model, forced by European Centre for Medium‐Range Weather Forecasts ERA‐Interim reanalyses updated surface area density, successfully simulates NO 2...
Abstract. The first concerted multi-model intercomparison of halogenated very short-lived substances (VSLS) has been performed, within the framework ongoing Atmospheric Tracer Transport Model Intercomparison Project (TransCom). Eleven global models or model variants participated (nine chemical transport and two chemistry–climate models) by simulating major natural bromine VSLS, bromoform (CHBr3) dibromomethane (CH2Br2), over a 20-year period (1993–2012). Except for three simulations, all...
Abstract Up to now our understanding of the 11 year ozone solar cycle signal (SCS) in upper stratosphere has been largely based on Stratospheric Aerosol and Gas Experiment (SAGE) II (v6.2) data record, which indicated a large positive could not be reproduced by models, calling into question chemistry stratosphere. Here we present an analysis new v7.0 SAGE shows smaller SCS, due more realistic ozone‐temperature anticorrelation. New simulations from state‐of‐art 3‐D chemical transport model...
Abstract. We present novel measurements of five short-lived brominated source gases (CH2Br2, CHBr3, CH2ClBr, CHCl2Br and CHClBr2). These rather are an important bromine to the stratosphere, where they can lead depletion ozone. The have been obtained using in situ gas chromatography mass spectrometry (GC–MS) system on board High Altitude Long Range Research Aircraft (HALO). instrument is extremely sensitive due use chemical ionization, allowing detection limits lower parts per quadrillion...
Abstract Dichloromethane (CH 2 Cl ) and perchloroethylene (C 4 are chlorinated very short lived substances (Cl‐VSLS) with anthropogenic sources. Recent studies highlight the increasing influence of such compounds, particularly CH , on stratospheric chlorine budget therefore ozone depletion. Here, a multiyear global‐scale synthesis inversion was performed to optimize (2006–2017) C (2007–2017) emissions. The approach combines long‐term surface observations from global monitoring networks,...
Abstract With the successful implementation of Montreal Protocol on Substances that Deplete Ozone Layer, atmospheric abundance ozone-depleting substances continues to decrease slowly and Antarctic ozone hole is showing signs recovery. However, growing emissions unregulated short-lived anthropogenic chlorocarbons are offsetting some these gains. Here, we report an increase in from China industrially produced chlorocarbon, dichloromethane (CH 2 Cl ). The grew 231 (213–245) Gg yr −1 2011 628...