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191 results on '"Pickering, S. J."'

3. Large-Scale Features of Pliocene Climate: Results from the Pliocene Model Intercomparison Project

Author

Haywood, A. M, Hill, D.J, Dolan, A. M, Otto-Bliesner, B. L, Bragg, F, Chan, W.-L, Chandler, M. A, Contoux, C, Dowsett, H. J, Jost, A, Kamae, Y, Lohmann, G, Lunt, D. J, Abe-Ouchi, A, Pickering, S. J, Ramstein, G, Rosenbloom, N. A, Salzmann, U, Sohl, L, Stepanek, C, Ueda, H, Yan, Q, and Zhang, Z

Subjects
Meteorology And Climatology
Abstract

Climate and environments of the mid-Pliocene warm period (3.264 to 3.025 Ma) have been extensively studied.Whilst numerical models have shed light on the nature of climate at the time, uncertainties in their predictions have not been systematically examined. The Pliocene Model Intercomparison Project quantifies uncertainties in model outputs through a coordinated multi-model and multi-mode data intercomparison. Whilst commonalities in model outputs for the Pliocene are clearly evident, we show substantial variation in the sensitivity of models to the implementation of Pliocene boundary conditions. Models appear able to reproduce many regional changes in temperature reconstructed from geological proxies. However, data model comparison highlights that models potentially underestimate polar amplification. To assert this conclusion with greater confidence, limitations in the time-averaged proxy data currently available must be addressed. Furthermore, sensitivity tests exploring the known unknowns in modelling Pliocene climate specifically relevant to the high latitudes are essential (e.g. palaeogeography, gateways, orbital forcing and trace gasses). Estimates of longer-term sensitivity to CO2 (also known as Earth System Sensitivity; ESS), support previous work suggesting that ESS is greater than Climate Sensitivity (CS), and suggest that the ratio of ESS to CS is between 1 and 2, with a "best" estimate of 1.5.

Published
2013
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10. Dynamics of multiple swirling burner flows

Author

Aroussi, A., Pickering, S. J., and Tarr, S.

Subjects
Laser Doppler blood flowmetry -- Analysis, Anemometer -- Usage, Hydraulic measurements -- Measurement, Engineering and manufacturing industries
Abstract

Byline: A. Aroussi, S. J. Pickering, S. Tarr Numerical predictions of four counter and co-rotating swirling flows issuing from small-scale low NOx burners have been performed and compared to laser Doppler anemometry (LDA) measurements. The results demonstrate that the near-burner features, such as the central reverse flow zones and the mixing of the burner jets, are resolved correctly by the computational model. Predicted tangential velocity components are in good agreement with the LDA measurements, and show the correct swirl velocity profiles and rate of decay. The anti-gearing phenomenon associated with the entrainment pattern of the counter and co-rotating burner arrays, where flow is entrained into the centre of the array against the direction of swirl, is captured by the LDA measurements and is predicted by the CFD model. Predicted rates of entrainment of surrounding air by the counter and co-rotating burners intimate that a counter-rotating burner array entrains at a greater rate than a single burner. A co-rotating system, however, entrains at a lower rate. The ability to control levels of entrainment may provide the means of further controlling air staging in real furnaces. The research demonstrates that multi-burner systems may be characterised in terms of the number of burners, their rotational direction, the burner pitch and the degree of entrainment.

Published
2003

13. Challenges in reconstructing terrestrial warming of the Pliocene revealed by data-model discord

Author

Salzmann, U., Dolan, A. M., Haywood, A. M., Chan, W.-L., Voss, J., Hill, D. J., Lunt, D. J., Abe-Ouchi, A., Otto-Bliesner, B., Bragg, F., Chandler, M. A., Contoux, C., Dowsett, H. J., Jost, A., Kamae, Y., Lohmann, Gerrit, Pickering, S. J., Pound, M. J., Ramstein, G., Rosenbloom, N. A., Sohl, L., Stepanek, Christian, Ueda, H., and Zhang, Z.

Abstract

Comparing simulations of key warm periods in Earth history with contemporaneous geological proxy data is a useful approach for evaluating the ability of climate models to simulate warm, high-CO2 climates that are unprecedented in the more recent past. Here we use a global data set of confidence-assessed, proxy-based temperature estimates and biome reconstructions to assess the ability of eight models to simulate warm terrestrial climates of the Pliocene epoch. The Late Pliocene, 3.6–2.6 million years ago, is an accessible geological interval to understand climate processes of a warmer world. We show that model-predicted surface air temperatures reveal a substantial cold bias in the Northern Hemisphere. Particularly strong data–model mismatches in mean annual temperatures (up to 18 °C) exist in northern Russia. Our model sensitivity tests identify insufficient temporal constraints hampering the accurate configuration of model boundary conditions as an important factor impacting on data–model discrepancies. We conclude that to allow a more robust evaluation of the ability of present climate models to predict warm climates, future Pliocene data–model comparison studies should focus on orbitally defined time slices.

Published
2013

16. Challenges in quantifying Pliocene terrestrial warming revealed by data–model discord

Author

Salzmann, U., Dolan, A. M., Haywood, A. M., Chan, W.-L., Voss, J., Hill, D. J., Abe-Ouchi, A., Otto-Bliesner, B., Bragg, F. J., Chandler, M. A., Contoux, C., Dowsett, H. J., Jost, A., Kamae, Y., Lohmann, Gerrit, Lunt, D. J., Pickering, S. J., Pound, M. J., Ramstein, G., Rosenbloom, N. A., Sohl, L., Stepanek, Christian, Ueda, H., Zhang, Z., Salzmann, U., Dolan, A. M., Haywood, A. M., Chan, W.-L., Voss, J., Hill, D. J., Abe-Ouchi, A., Otto-Bliesner, B., Bragg, F. J., Chandler, M. A., Contoux, C., Dowsett, H. J., Jost, A., Kamae, Y., Lohmann, Gerrit, Lunt, D. J., Pickering, S. J., Pound, M. J., Ramstein, G., Rosenbloom, N. A., Sohl, L., Stepanek, Christian, Ueda, H., and Zhang, Z.

Abstract

Comparing simulations of key warm periods in Earth history with contemporaneous geological proxy data is a useful approach for evaluating the ability of climate models to simulate warm, high-CO2 climates that are unprecedented in the more recent past. Here we use a global data set of confidence-assessed, proxy-based temperature estimates and biome reconstructions to assess the ability of eight models to simulate warm terrestrial climates of the Pliocene epoch. The Late Pliocene, 3.6–2.6 million years ago, is an accessible geological interval to understand climate processes of a warmer world. We show that model-predicted surface air temperatures reveal a substantial cold bias in the Northern Hemisphere. Particularly strong data–model mismatches in mean annual temperatures (up to 18 °C) exist in northern Russia. Our model sensitivity tests identify insufficient temporal constraints hampering the accurate configuration of model boundary conditions as an important factor impacting on data–model discrepancies. We conclude that to allow a more robust evaluation of the ability of present climate models to predict warm climates, future Pliocene data–model comparison studies should focus on orbitally defined time slices.

Published
2013

17. Large-scale features of Pliocene climate: results from the Pliocene Model Intercomparison Project

Author

Haywood, A. M., Hill, D. J., Dolan, A. M., Otto-Bliesner, B. L., Bragg, F., Chan, W.-L., Chandler, M. A., Contoux, C., Dowsett, H. J., Jost, A., Kamae, Y., Lohmann, Gerrit, Lunt, D. J., Abe-Ouchi, A., Pickering, S. J., Ramstein, G., Rosenbloom, N. A., Salzmann, U., Sohl, L., Stepanek, Christian, Ueda, H., Yan, Q., Zhang, Z., Haywood, A. M., Hill, D. J., Dolan, A. M., Otto-Bliesner, B. L., Bragg, F., Chan, W.-L., Chandler, M. A., Contoux, C., Dowsett, H. J., Jost, A., Kamae, Y., Lohmann, Gerrit, Lunt, D. J., Abe-Ouchi, A., Pickering, S. J., Ramstein, G., Rosenbloom, N. A., Salzmann, U., Sohl, L., Stepanek, Christian, Ueda, H., Yan, Q., and Zhang, Z.

Abstract

Climate and environments of the mid-Pliocene warm period (3.264 to 3.025 Ma) have been extensively studied. Whilst numerical models have shed light on the nature of climate at the time, uncertainties in their predictions have not been systematically examined. The Pliocene Model Intercomparison Project quantifies uncertainties in model outputs through a coordinated multi-model and multi-model/data intercomparison. Whilst commonalities in model outputs for the Pliocene are clearly evident, we show substantial variation in the sensitivity of models to the implementation of Pliocene boundary conditions. Models appear able to reproduce many regional changes in temperature reconstructed from geological proxies. However, data/model comparison highlights that models potentially underestimate polar amplification. To assert this conclusion with greater confidence, limitations in the time-averaged proxy data currently available must be addressed. Furthermore, sensitivity tests exploring the known unknowns in modelling Pliocene climate specifically relevant to the high latitudes are essential (e.g. palaeogeography, gateways, orbital forcing and trace gasses). Estimates of longer-term sensitivity to CO2 (also known as Earth System Sensitivity; ESS), support previous work suggesting that ESS is greater than Climate Sensitivity (CS), and suggest that the ratio of ESS to CS is between 1 and 2, with a "best" estimate of 1.5.

Published
2013

21. Supplementary material to "Large-scale features of Pliocene climate: results from the Pliocene Model Intercomparison Project"

Author

Haywood, A. M., primary, Hill, D. J., additional, Dolan, A. M., additional, Otto-Bliesner, B., additional, Bragg, F., additional, Chan, W.-L., additional, Chandler, M. A., additional, Contoux, C., additional, Jost, A., additional, Kamae, Y., additional, Lohmann, G., additional, Lunt, D. J., additional, Abe-Ouchi, A., additional, Pickering, S. J., additional, Ramstein, G., additional, Rosenbloom, N. A., additional, Sohl, L., additional, Stepanek, C., additional, Yan, Q., additional, Ueda, H., additional, and Zhang, Z., additional

Published
2012
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22. Large-scale features of Pliocene climate: results from the Pliocene Model Intercomparison Project

Author

Haywood, A. M., primary, Hill, D. J., additional, Dolan, A. M., additional, Otto-Bliesner, B., additional, Bragg, F., additional, Chan, W.-L., additional, Chandler, M. A., additional, Contoux, C., additional, Jost, A., additional, Kamae, Y., additional, Lohmann, G., additional, Lunt, D. J., additional, Abe-Ouchi, A., additional, Pickering, S. J., additional, Ramstein, G., additional, Rosenbloom, N. A., additional, Sohl, L., additional, Stepanek, C., additional, Yan, Q., additional, Ueda, H., additional, and Zhang, Z., additional

Published
2012
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23. Intercomparison of modal and sectional aerosol microphysics representations within the same 3-D global chemical transport model

Author

Mann, G. W., primary, Carslaw, K. S., additional, Ridley, D. A., additional, Spracklen, D. V., additional, Pringle, K. J., additional, Merikanto, J., additional, Korhonen, H., additional, Schwarz, J. P., additional, Lee, L. A., additional, Manktelow, P. T., additional, Woodhouse, M. T., additional, Schmidt, A., additional, Breider, T. J., additional, Emmerson, K. M., additional, Reddington, C. L., additional, Chipperfield, M. P., additional, and Pickering, S. J., additional

Published
2012
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47. Large-scale features of Pliocene climate: results from the Pliocene Model Intercomparison Project.

Author

Haywood, A. M., Hill, D. J., Dolan, A. M., Otto-Bliesner, B., Bragg, F., Chan, W.-L., Chandler, M. A., Contoux, C., Jost, A., Kamae, Y., Lohmann, G., Lunt, D. J., Abe-Ouchi, A., Pickering, S. J., Ramstein, G., Rosenbloom, N. A., Sohl, L., Stepanek, C., Yan, Q., and Ueda, H.

Abstract

Climate and environments of the mid-Pliocene Warm Period (3.264 to 3.025 Ma) have been extensively studied. Whilst numerical models have shed light on the nature of climate at the time, uncertainties in their predictions have not been systematically examined. The Pliocene Model Intercomparison Project quantifies uncertainties in model outputs through a co-ordinated multi-model and multi-model/data intercomparison. Whilst commonalities in model outputs for the Pliocene are evident, we show substantial variation in the sensitivity of models to the implementation of Pliocene boundary conditions. Models appear able to reproduce many regional changes in temperature reconstructed from geological proxies. However, data/model comparison highlights the potential for models to underestimate polar amplification. To assert this conclusion with greater confidence, limitations in the time-averaged proxy data currently available must be addressed. Sensitivity tests exploring the "known unknowns" in modeling Pliocene climate specifically relevant to the high-latitudes are also essential (e.g. palaeogeography, gateways, orbital forcing and trace gasses). Estimates of longer-term sensitivity to CO2 (also known as Earth System Sensitivity; ESS), suggest that ESS is greater than Climate Sensitivity (CS), and that the ratio of ESS to CS is between 1 and 2, with a best estimate of 1.5. [ABSTRACT FROM AUTHOR]

Published
2012
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