ORCID Profile
0000-0003-2062-6556
Current Organisations
Cranfield University
,
University of Oxford
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Publisher: Copernicus GmbH
Date: 27-01-2020
Publisher: Elsevier BV
Date: 06-2019
Publisher: Springer Science and Business Media LLC
Date: 06-2018
DOI: 10.1038/S41586-018-0181-4
Abstract: The United Nations' Paris Agreement includes the aim of pursuing efforts to limit global warming to only 1.5 °C above pre-industrial levels. However, it is not clear what the resulting climate would look like across the globe and over time. Here we show that trajectories towards a '1.5 °C warmer world' may result in vastly different outcomes at regional scales, owing to variations in the pace and location of climate change and their interactions with society's mitigation, adaptation and vulnerabilities to climate change. Pursuing policies that are considered to be consistent with the 1.5 °C aim will not completely remove the risk of global temperatures being much higher or of some regional extremes reaching dangerous levels for ecosystems and societies over the coming decades.
Publisher: Copernicus GmbH
Date: 24-11-2020
Publisher: Copernicus GmbH
Date: 27-01-2020
DOI: 10.5194/GMD-2019-379
Abstract: Abstract. Here we present a Generalised Impulse Response (GIR) model for use in probabilistic future climate and scenario exploration, integrated assessment, policy analysis and teaching. This model is based on a set of only six equations, which correspond to the standard Impulse Response model used for greenhouse gas metric calculations by the IPCC, plus one physically-motivated additional equation to represent state-dependent feedbacks on the response timescales of each greenhouse gas cycle. These six equations are simple and transparent enough to be easily understood and implemented in other models without reliance on the original source code, but flexible enough to reproduce observed well-mixed greenhouse gas (GHG) concentrations and atmospheric lifetimes, best-estimate effective radiative forcing, and temperature response. We describe the assumptions and methods used in selecting the default parameters, but emphasize that other methods would be equally valid: our focus here is on identifying a minimum level of structural complexity. The tunable nature of the model lends it to use as a fully transparent emulator of complex Earth System Models, such as those participating in CMIP6, while also reproducing the behaviour of other simple climate models. We argue that this GIR model is adequate to reproduce the global temperature response to global emissions and effective radiative forcing, and that it should be used as a lowest-common denominator to provide consistency and continuity between different climate assessments. The model design is such that it can be written in tabular data analysis software, such as Excel, increasing the potential user base considerably.
Publisher: Copernicus GmbH
Date: 31-07-2208
Abstract: Abstract. Measurements of the radical species OH and HO2 were made using the fluorescence assay by gas expansion (FAGE) technique during a series of night-time and daytime flights over the UK in summer 2010 and winter 2011. OH was not detected above the instrument's 1σ limit of detection during any of the night-time flights or during the winter daytime flights, placing upper limits on [OH] of 1.8 × 106 molecule cm−3 and 6.4 × 105 molecule cm−3 for the summer and winter flights, respectively. HO2 reached a maximum concentration of 3.2 × 108 molecule cm−3 (13.6 pptv) during a night-time flight on 20 July 2010, when the highest concentrations of NO3 and O3 were also recorded. An analysis of the rates of reaction of OH, O3, and the NO3 radical with measured alkenes indicates that the summer night-time troposphere can be as important for the processing of volatile organic compounds (VOCs) as the winter daytime troposphere. An analysis of the instantaneous rate of production of HO2 from the reactions of O3 and NO3 with alkenes has shown that, on average, reactions of NO3 dominated the night-time production of HO2 during summer and reactions of O3 dominated the night-time HO2 production during winter.
Publisher: Copernicus GmbH
Date: 10-12-2014
DOI: 10.5194/ACP-14-13159-2014
Abstract: Abstract. Airborne and ground-based measurements of methane (CH4), carbon dioxide (CO2) and boundary layer thermodynamics were recorded over the Fennoscandian landscape (67–69.5° N, 20–28° E) in July 2012 as part of the MAMM (Methane and other greenhouse gases in the Arctic: Measurements, process studies and Modelling) field c aign. Employing these airborne measurements and a simple boundary layer box model, net regional-scale (~ 100 km) fluxes were calculated to be 1.2 ± 0.5 mg CH4 h−1 m−2 and −350 ± 143 mg CO2 h−1 m−2. These airborne fluxes were found to be relatively consistent with seasonally averaged surface chamber (1.3 ± 1.0 mg CH4 h−1 m−2) and eddy covariance (1.3 ± 0.3 mg CH4 h−1 m−2 and −309 ± 306 mg CO2 h−1 m−2) flux measurements in the local area. The internal consistency of the aircraft-derived fluxes across a wide swath of Fennoscandia coupled with an excellent statistical comparison with local seasonally averaged ground-based measurements demonstrates the potential scalability of such localised measurements to regional-scale representativeness. Comparisons were also made to longer-term regional CH4 climatologies from the JULES (Joint UK Land Environment Simulator) and HYBRID8 land surface models within the area of the MAMM c aign. The average hourly emission flux output for the summer period (July–August) for the year 2012 was 0.084 mg CH4 h−1 m−2 (minimum 0.0 and maximum 0.21 mg CH4 h−1 m−2) for the JULES model and 0.088 mg CH4 h−1 m−2 (minimum 0.0008 and maximum 1.53 mg CH4 h−1 m−2) for HYBRID8. Based on these observations both models were found to significantly underestimate the CH4 emission flux in this region, which was linked to the under-prediction of the wetland extents generated by the models.
Publisher: Copernicus GmbH
Date: 24-11-2020
DOI: 10.5194/GMD-2020-390
Abstract: Abstract. Here we present an update to the FaIR model for use in probabilistic future climate and scenario exploration, integrated assessment, policy analysis and education. In this update we have focussed on identifying a minimum level of structural complexity in the model. The result is a set of six equations, five of which correspond to the standard Impulse Response model used for greenhouse gas (GHG) metric calculations in the IPCC's fifth assessment report, plus one additional physically-motivated additional equation to represent state-dependent feedbacks on the response timescales of each greenhouse gas cycle. This additional equation is necessary to reproduce non-linearities in the carbon cycle apparent in both Earth System Models and observations. These six equations are transparent and sufficiently simple that the model is able to be written in standard tabular data analysis packages, such as Excel increasing the potential user base considerably. However, we demonstrate that the equations are flexible enough to be tuned to emulate the behaviour of several key processes within more complex models from CMIP6. The model is exceptionally quick to run, making it ideal for integrating large probabilistic ensembles. We apply a constraint based on the current estimates of the global warming trend to a one million member ensemble, using the constrained ensemble to make scenario dependent projections and infer ranges for properties of the climate system. Through these analyses, we reaffirm that simple climate models (unlike more complex models) are not themselves intrinsically biased hot or cold: it is the choice of parameters and how those are selected that determines the model response, something that appears to have been misunderstood in the past. This updated FaIR model is able to reproduce the global climate system response to GHG and aerosol emissions with sufficient accuracy to be useful in a wide range of applications and therefore could be used as a lowest common denominator model to provide consistency in different contexts. The fact that FaIR can be written down in just six equations greatly aids transparency in such contexts.
Publisher: American Geophysical Union (AGU)
Date: 13-12-2016
DOI: 10.1002/2016JD026006
Publisher: Copernicus GmbH
Date: 27-05-2021
Abstract: Abstract. Here we present an update to the FaIR model for use in probabilistic future climate and scenario exploration, integrated assessment, policy analysis, and education. In this update we have focussed on identifying a minimum level of structural complexity in the model. The result is a set of six equations, five of which correspond to the standard impulse response model used for greenhouse gas (GHG) metric calculations in the IPCC's Fifth Assessment Report, plus one additional physically motivated equation to represent state-dependent feedbacks on the response timescales of each greenhouse gas cycle. This additional equation is necessary to reproduce non-linearities in the carbon cycle apparent in both Earth system models and observations. These six equations are transparent and sufficiently simple that the model is able to be ported into standard tabular data analysis packages, such as Excel, increasing the potential user base considerably. However, we demonstrate that the equations are flexible enough to be tuned to emulate the behaviour of several key processes within more complex models from CMIP6. The model is exceptionally quick to run, making it ideal for integrating large probabilistic ensembles. We apply a constraint based on the current estimates of the global warming trend to a million-member ensemble, using the constrained ensemble to make scenario-dependent projections and infer ranges for properties of the climate system. Through these analyses, we reaffirm that simple climate models (unlike more complex models) are not themselves intrinsically biased “hot” or “cold”: it is the choice of parameters and how those are selected that determines the model response, something that appears to have been misunderstood in the past. This updated FaIR model is able to reproduce the global climate system response to GHG and aerosol emissions with sufficient accuracy to be useful in a wide range of applications and therefore could be used as a lowest-common-denominator model to provide consistency in different contexts. The fact that FaIR can be written down in just six equations greatly aids transparency in such contexts.
Publisher: Springer Science and Business Media LLC
Date: 28-01-2022
Publisher: Copernicus GmbH
Date: 30-01-2015
DOI: 10.5194/ACPD-15-2997-2015
Abstract: Abstract. Measurements of the radical species OH and HO2 were made using the Fluorescence Assay by Gas Expansion (FAGE) technique during a series of nighttime and daytime flights over the UK in summer 2010 and winter 2011. OH was not detected above the instrument's 1σ limit of detection during any of the nighttime flights or during the winter daytime flights, placing upper limits on [OH] of 1.8 × 106 molecule cm−3 and 6.4 × 105 molecule cm−3 for the summer and winter flights, respectively. HO2 reached a maximum concentration of 3.2 × 108 molecule cm−3 (13.6 pptv) during a nighttime flight on 20 July 2010, when the highest concentrations of NO3 and O3 were also recorded. Analysis of the rates of reaction of OH, O3, and the NO3 radical with measured alkenes indicates that the summer nighttime troposphere can be as important for the processing of VOCs as the winter daytime troposphere. Analysis of the instantaneous rate of production of HO2 from the reactions of O3 and NO3 with alkenes has shown that, on average, reactions of NO3 dominated nighttime production of HO2 during summer, and reactions of O3 dominated nighttime HO2 production during winter.
Publisher: American Geophysical Union (AGU)
Date: 19-07-2017
DOI: 10.1002/2017JD026626
Publisher: Copernicus GmbH
Date: 30-01-2015
Publisher: Copernicus GmbH
Date: 31-01-2012
Abstract: Abstract. A Lagrangian model of photochemistry and mixing is described (CiTTyCAT, stemming from the Cambridge Tropospheric Trajectory model of Chemistry And Transport), which is suitable for transport and chemistry studies throughout the troposphere. Over the last five years, the model has been developed in parallel at several different institutions and here those developments have been incorporated into one "community" model and documented for the first time. The key photochemical developments include a new scheme for biogenic volatile organic compounds and updated emissions schemes. The key physical development is to evolve composition following an ensemble of trajectories within neighbouring air-masses, including a simple scheme for mixing between them via an evolving "background profile", both within the boundary layer and free troposphere. The model runs along trajectories pre-calculated using winds and temperature from meteorological analyses. In addition, boundary layer height and precipitation rates, output from the analysis model, are interpolated to trajectory points and used as inputs to the mixing and wet deposition schemes. The model is most suitable in regimes when the effects of small-scale turbulent mixing are slow relative to advection by the resolved winds so that coherent air-masses form with distinct composition and strong gradients between them. Such air-masses can persist for many days while stretching, folding and thinning. Lagrangian models offer a useful framework for picking apart the processes of air-mass evolution over inter-continental distances, without being hindered by the numerical diffusion inherent to global Eulerian models. The model, including different box and trajectory modes, is described and some output for each of the modes is presented for evaluation. The model is available for download from a Subversion-controlled repository by contacting the corresponding authors.
Publisher: Copernicus GmbH
Date: 31-03-2014
DOI: 10.5194/ACPD-14-8455-2014
Abstract: Abstract. Airborne and ground-based measurements of methane (CH4), carbon dioxide (CO2) and boundary layer thermodynamics were recorded over the Fennoscandian wetlands in July 2012 as part of the MAMM (Methane and other greenhouse gases in the Arctic – Measurements, process studies and Modelling) field c aign. Employing these airborne measurements and a~simple boundary layer box model, net regional scale (~100 km) fluxes were calculated to be 1.2 ± 0.5 mg CH4 h−1 m−2 and −350 ± 143 mg CO2 h−1 m−2. These airborne fluxes were found to be relatively consistent with seasonally-averaged surface chamber (1.3 ± 1.0 mg CH4 h−1 m−2) and eddy covariance (1.3 ± 0.3 mg CH4 h−1 m−2 and −309 ± 306 mg CO2 h−1 m−2) flux measurements in the local area. The internal consistency of the aircraft-derived fluxes across a wide swath of Fennoscandia coupled with an excellent statistical comparison with local seasonally-averaged ground-based measurements demonstrates the potential scalability of such localised measurements to regional scale representivity. Comparisons were also made to longer term regional CH4 climatologies from the JULES (Joint UK Land Environment Simulator) and Hybrid8 land surface models within the area of the MAMM c aign. The average hourly emission flux output for the summer period (July–August) across the years 1980 to 2010 was 0.054 mg CH4 h−1 m−2 (minimum 0.0 and maximum 0.38 mg CH4 h−1 m−2) for the JULES model and 0.073 mg CH4 h−1 m−2 (minimum −0.0018 and maximum 4.62 mg CH4 h−1 m−2) for Hybrid8. Based on these observations both models were found to significantly underestimate the CH4 emission flux in this region, which was linked to the under prediction of the wetland extents generated by the models.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Michelle Cain.