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102. Development and evaluation of an Earth-System model – HadGEM2

Author

Collins, W. J., primary, Bellouin, N., additional, Doutriaux-Boucher, M., additional, Gedney, N., additional, Halloran, P., additional, Hinton, T., additional, Hughes, J., additional, Jones, C. D., additional, Joshi, M., additional, Liddicoat, S., additional, Martin, G., additional, O'Connor, F., additional, Rae, J., additional, Senior, C., additional, Sitch, S., additional, Totterdell, I., additional, Wiltshire, A., additional, and Woodward, S., additional

Published
2011
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104. The HadGEM2-ES implementation of CMIP5 centennial simulations

Author

Jones, C. D., primary, Hughes, J. K., additional, Bellouin, N., additional, Hardiman, S. C., additional, Jones, G. S., additional, Knight, J., additional, Liddicoat, S., additional, O'Connor, F. M., additional, Andres, R. J., additional, Bell, C., additional, Boo, K.-O., additional, Bozzo, A., additional, Butchart, N., additional, Cadule, P., additional, Corbin, K. D., additional, Doutriaux-Boucher, M., additional, Friedlingstein, P., additional, Gornall, J., additional, Gray, L., additional, Halloran, P. R., additional, Hurtt, G., additional, Ingram, W. J., additional, Lamarque, J.-F., additional, Law, R. M., additional, Meinshausen, M., additional, Osprey, S., additional, Palin, E. J., additional, Parsons Chini, L., additional, Raddatz, T., additional, Sanderson, M. G., additional, Sellar, A. A., additional, Schurer, A., additional, Valdes, P., additional, Wood, N., additional, Woodward, S., additional, Yoshioka, M., additional, and Zerroukat, M., additional

Published
2011
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107. Effects of climate-induced changes in isoprene emissions after the eruption of Mount Pinatubo

Author

Telford, P. J., primary, Lathière, J., additional, Abraham, N. L., additional, Archibald, A. T., additional, Braesicke, P., additional, Johnson, C. E., additional, Morgenstern, O., additional, O'Connor, F. M., additional, Pike, R. C., additional, Wild, O., additional, Young, P. J., additional, Beerling, D. J., additional, Hewitt, C. N., additional, and Pyle, J., additional

Published
2010
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111. Arctic ozone loss in threshold conditions: Match observations in 1997/1998 and 1998/1999

Author

Schulz, Astrid, Rex, Markus, Harris, N. R. P., Braathen, G. O., Reimer, E., Alfier, R., Kilbane-Dawe, I., Eckermann, S., Allaart, M., Alpers, M., Bojkov, B., Cisneros, J., Claude, H., Cuevas, E., Davies, J., Backer, H. de, Dier, H., Dorokhov, V., Fast, H., Godin, S., Johnson, B., Kois, B., Kondo, Y., Kosmidis, E., Kyrö, E., Litynska, Z., Mikkelsen, I. S., Molyneux, M. J., Murphy, G., Nagai, T., Nakane, H., O'Connor, F., Parrondo, C., Schmidlin, F. J., Skrivankova, P., Varotsos, C., Vialle, C., Viatte, P., Yushkov, V., Zerefos, C., von der Gathen, Peter, Schulz, Astrid, Rex, Markus, Harris, N. R. P., Braathen, G. O., Reimer, E., Alfier, R., Kilbane-Dawe, I., Eckermann, S., Allaart, M., Alpers, M., Bojkov, B., Cisneros, J., Claude, H., Cuevas, E., Davies, J., Backer, H. de, Dier, H., Dorokhov, V., Fast, H., Godin, S., Johnson, B., Kois, B., Kondo, Y., Kosmidis, E., Kyrö, E., Litynska, Z., Mikkelsen, I. S., Molyneux, M. J., Murphy, G., Nagai, T., Nakane, H., O'Connor, F., Parrondo, C., Schmidlin, F. J., Skrivankova, P., Varotsos, C., Vialle, C., Viatte, P., Yushkov, V., Zerefos, C., and von der Gathen, Peter

Abstract

Chemical ozone loss rates inside the Arctic polar vortexweredetermined in early 1998 and early 1999 by using the Match techniquebased on coordinated ozonesonde measurements. These two wintersprovide the only opportunities in recent years to investigatechemical ozone loss in a warm Arctic vortex under thresholdconditions, i.e., where the preconditions for chlorine activation,and hence ozone destruction, only occurred occasionally. In 1998,results were obtained in January and February between 410 and 520 K.The overall ozone loss was observed to be largely insignificant,with the exception of late February, when those air parcels exposedto temperatures below 195 K were affected by chemical ozone loss. In1999, results are confined to the 475 K isentropic level, where nosignificant ozone loss was observed. Average temperatures were some8 -10 K higher than those in 1995, 1996, and 1997,when substantial chemical ozone loss occurred. The results underlinethe strong dependence of the chemical ozone loss on thestratospheric temperatures. This study shows that enhanced chlorinealone does not provide a sufficient condition for ozone loss. Theevolution of stratospheric temperatures over the next decade will bethe determining factor for the amount of wintertime chemical ozoneloss in the Arctic stratosphere.

Published
2001

114. Solid state ozone sensors for the future: light weight, low power and continuous operation

Author

Harris, N.R.P., Guirlet, M., Amanatidis, G.T., Hansford, G.M., Sanderson, M.G., Freshwater, R.A., Utembe, S., Bosch, R., Cox, R.A., Jones, R.L., Pratt, K.E., Williams, D.E., Smit, H., Helten, M., O'Connor, F., Vaughan, G., Roscoe, H.K., Harris, N.R.P., Guirlet, M., Amanatidis, G.T., Hansford, G.M., Sanderson, M.G., Freshwater, R.A., Utembe, S., Bosch, R., Cox, R.A., Jones, R.L., Pratt, K.E., Williams, D.E., Smit, H., Helten, M., O'Connor, F., Vaughan, G., and Roscoe, H.K.

Published
2000

115. Ozone loss rates determined with Match: Arctic winters 1997/98 and 1998/99

Author

Schulz, Astrid, Rex, Markus, Harris, N. R. P., Braathen, G. O., Kyrö, E., Reimer, E., Alfier, R., Kilbane-Dawe, I., Allaart, M., Alpers, M., Bojkov, B. R., Cisneros, J., Claude, H., Cuevas, E., Davies, J., De Backer, H., Dier, H., Dorokhov, V., Fast, H., Johnson, B., Kois, B., Kosmidis, E., Litynska, Z., Mikkelsen, I. S., Molyneux, M., Murphy, G., Nakane, H., O'Connor, F., Parrondo, C., Skrivankova, P., Varotsos, C., Vialle, C., Viatte, P., Yushkov, V., Zerefos, C., von der Gathen, Peter, Schulz, Astrid, Rex, Markus, Harris, N. R. P., Braathen, G. O., Kyrö, E., Reimer, E., Alfier, R., Kilbane-Dawe, I., Allaart, M., Alpers, M., Bojkov, B. R., Cisneros, J., Claude, H., Cuevas, E., Davies, J., De Backer, H., Dier, H., Dorokhov, V., Fast, H., Johnson, B., Kois, B., Kosmidis, E., Litynska, Z., Mikkelsen, I. S., Molyneux, M., Murphy, G., Nakane, H., O'Connor, F., Parrondo, C., Skrivankova, P., Varotsos, C., Vialle, C., Viatte, P., Yushkov, V., Zerefos, C., and von der Gathen, Peter

Published
2000

124. Accuracy of measurements of total ozone by a SAOZ ground-based zenith sky visible spectrometer

Author

Sarkissian, A., Vaughan, G., Roscoe, H. K., Bartlett, L. M., O'Connor, F. M., Drew, D. G., Hughes, P. A., Moore, D. M., Sarkissian, A., Vaughan, G., Roscoe, H. K., Bartlett, L. M., O'Connor, F. M., Drew, D. G., Hughes, P. A., and Moore, D. M.

Abstract

During a 2-week intercomparison of ground-based zenith sky visible spectrometers in September 1994 at Camborne, United Kingdom (50°N, 5°W), ozone profiles were measured by electrochemical cell (ECC) sondes during 11 twilight periods. We use these profiles and a radiative transfer model to calculate separate air mass factors (AMFs) for each twilight period. We examine ozone data from one of the spectrometers of the Système d'Analyse par Observation Zénithale (SAOZ) design and we show that these separate AMFs give very straight Langley plots, except at solar zenith angles exceeding 90°. Total ozone calculated using these AMFs, by a variety of commonly used procedures, agrees with the total ozone calculated by vertically integrating the sonde profiles, with mean differences of 0 to 7 Dobson units (DU), depending on the method, and standard deviations of 9 to 11 DU (1 σ). Total ozone calculated using the best procedure (i.e., averaging twilight values), which is not sensitive to errors in the gradients of AMFs, gave excellent agreement whether using separate AMFs or fixed climatological AMFs. We analyse the variance of the data set and several sources of systematic error in the measurements. We also illustrate from an example during the campaign that such analyses are pointless in the presence of a strong jet stream, which can give rise to changes in ozone during the course of the day that are large enough to invalidate the Langley plot

Published
1997

125. An intercomparison of ground-based UV-visible sensors of ozone and NO2

Author

Vaughan, G., Roscoe, H. K., Bartlett, L. M., O'Connor, F. M., Sarkissian, A., Van Roozendael, M., Lambert, J-C, Simon, P. C., Karlsen, K., Høiskar, B. A. Kåstad, Fish, D. J., Jones, R. L., Freshwater, R. A., Pommereau, J-P., Goutail, F., Andersen, S. B., Drew, D. G., Hughes, P. A., Moore, D., Mellqvist, J., Hegels, E., Klupfel, T., Erle, F., Pfeilsticker, K., Platt, U., Vaughan, G., Roscoe, H. K., Bartlett, L. M., O'Connor, F. M., Sarkissian, A., Van Roozendael, M., Lambert, J-C, Simon, P. C., Karlsen, K., Høiskar, B. A. Kåstad, Fish, D. J., Jones, R. L., Freshwater, R. A., Pommereau, J-P., Goutail, F., Andersen, S. B., Drew, D. G., Hughes, P. A., Moore, D., Mellqvist, J., Hegels, E., Klupfel, T., Erle, F., Pfeilsticker, K., and Platt, U.

Abstract

An intercomparison of zenith-sky UV-visible spectrometers was held at Camborne, UK, for 2 weeks in September 1994. Eleven instruments participated, from nine different European institutes which were involved with the Second European Stratospheric Arctic and Mid-latitude Experiment (SESAME) campaign. Four instruments were of the Systeme d'Analyse d'Observations Zénithales (SAOZ) type, while the rest were particular to the institutes involved. The results showed that the SAOZ instruments were consistent to within 3% (10 DU) for ozone and 5% for NO2. For ozone the results from these instruments agreed well with total ozone measurements by Dobson and Brewer spectrophotometers and integrated ozonesondes when the air mass factors for the SAOZ were calculated using the ozonesonde profiles. Differences of up to 10% in ozone and 30% in NO2 were found between different instruments. In some cases these differences are attributable to the different absorption cross sections used in the analysis of the spectra, but other discrepancies remain to be investigated. A prominent source of error identified in the campaign was uncertainty in the derivation of the amount of absorber in the reference spectrum, which can contribute an error of up to 3% (10 DU) in ozone and 1.5×1014 molecules cm−2 in NO2.

Published
1997

126. Prolonged stratospheric ozone loss in the 1995/96 Arctic winter

Author

Rex, Markus, Harris, N. R. P., von der Gathen, Peter, Lehmann, Ralph, Braathen, G. O., Reimer, E., Beck, A., Chipperfield, M. P., Alfier, R., Allaart, M., O'Connor, F., Dier, H., Dorokhov, V., Fast, H., Gil, M., Kyrö, E., Litynska, Z., Mikkelsen, I. S., Molyneux, M. G., Nakane, H., Notholt, Justus, Rummukainen, M., Viatte, P., Wenger, J., Rex, Markus, Harris, N. R. P., von der Gathen, Peter, Lehmann, Ralph, Braathen, G. O., Reimer, E., Beck, A., Chipperfield, M. P., Alfier, R., Allaart, M., O'Connor, F., Dier, H., Dorokhov, V., Fast, H., Gil, M., Kyrö, E., Litynska, Z., Mikkelsen, I. S., Molyneux, M. G., Nakane, H., Notholt, Justus, Rummukainen, M., Viatte, P., and Wenger, J.

Abstract

It is well established that extensive depletion of ozone, initiated by heterogenous reactions on polar stratospheric clouds(PSCs) can occur in both the Arctic and Antarctic lower stratosphere. Moreover, it has been shown that ozone lossrates in the Arctic region in recent years reached values comparable to those over the Antarctic. But until now theaccumulated ozone losses over the Arctic have been the smaller, mainly because the period of Arctic ozone loss hasnot-unlike over the Antarctic-persisted well into springtime. Here we report the occurrence-during the unusuallycold 1995-96 Arctic winter-of the highest recorded chemical ozone loss over the Arctic region. Two new kinds ofbehaviour were observed. First, ozone loss at some altitudes was observed long after the last exposure to PSCs. Thiscontinued loss appears to be due to a removal of the nitrogen species that slow down chemical ozone depletion. Second,in another altitude range ozone loss rates decreased while PSCs were still present, apparently because of an earlytransformation of the ozone-destroying chlorine species into less active chlorinenitrate. The balance between these twocounteracting mechanisms is probably a fine one, determined by small differences in wintertime stratospherictemperatures. If the apparent cooling trend in the Arctic stratosphere is real, more dramatic ozone losses may occurin the future.

Published
1997

128. Arctic ozone loss in threshold conditions: Match observations in 1997/1998 and 1998/1999

Author

Schulz, A., primary, Rex, M., additional, Harris, N. R. P., additional, Braathen, G. O., additional, Reimer, E., additional, Alfier, R., additional, Kilbane‐Dawe, I., additional, Eckermann, S., additional, Allaart, M., additional, Alpers, M., additional, Bojkov, B., additional, Cisneros, J., additional, Claude, H., additional, Cuevas, E., additional, Davies, J., additional, De Backer, H., additional, Dier, H., additional, Dorokhov, V., additional, Fast, H., additional, Godin, S., additional, Johnson, B., additional, Kois, B., additional, Kondo, Y., additional, Kosmidis, E., additional, Kyrö, E., additional, Litynska, Z., additional, Mikkelsen, I. S., additional, Molyneux, M. J., additional, Murphy, G., additional, Nagai, T., additional, Nakane, H., additional, O'Connor, F., additional, Parrondo, C., additional, Schmidlin, F. J., additional, Skrivankova, P., additional, Varotsos, C., additional, Vialle, C., additional, Viatte, P., additional, Yushkov, V., additional, Zerefos, C., additional, and von der Gathen, P., additional

Published
2001
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132. Aerosol microphysics simulations of the Mt. Pinatubo eruption with the UM-UKCA composition-climate model.

Author

Dhomse, S. S., Emmerson, K. M., Mann, G. W., Bellouin, N., Carslaw, K. S., Chipperfield, M. P., Hommel, R., Abraham, N. L., Telford, P., Braesicke, P., Dalvi, M., Johnson, C. E., O'Connor, F., Morgenstern, O., Pyle, J. A., Deshler, T., Zawodny, J. M., and Thomason, L. W.

Subjects
ATMOSPHERIC aerosols, MICROPHYSICS, ATMOSPHERIC models, PARTICLE size distribution, STRATOSPHERE
Abstract

We use a stratosphere-troposphere composition- climate model with interactive sulfur chemistry and aerosol microphysics, to investigate the effect of the 1991 Mount Pinatubo eruption on stratospheric aerosol properties. Satellite measurements indicate that shortly after the eruption, between 14 and 23 Tg of SO2 (7 to 11.5 Tg of sulfur) was present in the tropical stratosphere. Best estimates of the peak global stratospheric aerosol burden are in the range 19 to 26 Tg, or 3.7 to 6.7 Tg of sulfur assuming a composition of between 59 and 77% H2SO4. In light of this large uncertainty range, we performed two main simulations with 10 and 20 Tg of SO2 injected into the tropical lower stratosphere. Simulated stratospheric aerosol properties through the 1991 to 1995 period are compared against a range of available satellite and in situ measurements. Stratospheric aerosol optical depth (sAOD) and effective radius from both simulations show good qualitative agreement with the observations, with the timing of peak sAOD and decay timescale matching well with the observations in the tropics and mid-latitudes. However, injecting 20 Tg gives a factor of 2 too high stratospheric aerosol mass burden compared to the satellite data, with consequent strong high biases in simulated sAOD and surface area density, with the 10 Tg injection in much better agreement. Our model cannot explain the large fraction of the injected sulfur that the satellite-derived SO2 and aerosol burdens indicate was removed within the first few months after the eruption. We suggest that either there is an additional alternative loss pathway for the SO2 not included in our model (e.g. via accommodation into ash or ice in the volcanic cloud) or that a larger proportion of the injected sulfur was removed via cross-tropopause transport than in our simulations. We also critically evaluate the simulated evolution of the particle size distribution, comparing in detail to balloonborne optical particle counter (OPC) measurements from Laramie, Wyoming, USA (41 N). Overall, the model captures remarkably well the complex variations in particle concentration profiles across the different OPC size channels. However, for the 19 to 27 km injection height-range used here, both runs have a modest high bias in the lowermost stratosphere for the finest particles (radii less than 250 nm), and the decay timescale is longer in the model for these particles, with a much later return to background conditions. Also, whereas the 10 Tg run compared best to the satellite measurements, a significant low bias is apparent in the coarser size channels in the volcanically perturbed lower stratosphere. Overall, our results suggest that, with appropriate calibration, aerosol microphysics models are capable of capturing the observed variation in particle size distribution in the stratosphere across both volcanically perturbed and quiescent conditions. Furthermore, additional sensitivity simulations suggest that predictions with the models are robust to uncertainties in sub-grid particle formation and nucleation rates in the stratosphere. [ABSTRACT FROM AUTHOR]

Published
2014
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136. An intercomparison of ground-based UV-visible sensors of ozone and NO2

Author

Vaughan, G., primary, Roscoe, H. K., additional, Bartlett, L. M., additional, O'Connor, F. M., additional, Sarkissian, A., additional, Van Roozendael, M., additional, Lambert, J-C, additional, Simon, P. C., additional, Karlsen, K., additional, Høiskar, B. A. Kåstad, additional, Fish, D. J., additional, Jones, R. L., additional, Freshwater, R. A., additional, Pommereau, J-P., additional, Goutail, F., additional, Andersen, S. B., additional, Drew, D. G., additional, Hughes, P. A., additional, Moore, D., additional, Mellqvist, J., additional, Hegels, E., additional, Klupfel, T., additional, Erle, F., additional, Pfeilsticker, K., additional, and Platt, U., additional

Published
1997
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145. Evaluation of the new UKCA climate-composition model - Part 2: The Troposphere.

Author

O'Connor, F. M., Johnson, C. E., Morgenstern, O., Abraham, N. L., Braesicke, P., Dalvi, M., Folberth, G. A., Sanderson, M. G., Telford, P. J., Young, P. J., G. Zeng, Collins, W. J., and Pyle, J. A.

Subjects
*ATMOSPHERIC models, *CLIMATOLOGY, *PRECIPITATION scavenging, *TROPOSPHERE
Abstract

In this paper, we present a description of the tropospheric chemistry component of the UK Chemistry and Aerosols (UKCA) model which has been coupled to the Met Office Hadley Centre's HadGEM family of climate models. We assess the model's transport and scavenging processes, in particular focussing on convective transport, boundary layer mixing, wet scavenging and inter-hemispheric exchange. Simulations with UKCA of the short-lived radon tracer suggest that modelled distributions are comparable to those of other models and the comparison with observations indicate that apart from a few locations, boundary layer mixing and convective transport are effective in the model as a means of vertically re-distributing surface emissions of radon. Comparisons of modelled lead tracer concentrations with observations suggest that UKCA captures surface concentrations in both hemispheres very well although there is a tendency to underestimate the observed geographical and interannual variability in the Northern Hemisphere. In particular, UKCA replicates the shape and absolute concentrations of observed lead profiles, a key test in the evaluation of a model's wet scavenging scheme. The timescale for inter-hemispheric transport, calculated in the model using a simple krypton tracer experiment, does appear to be long relative to other models and could indicate deficiencies in tropical deep convection and/or insufficient boundary layer mixing. We also describe the main components of the tropospheric chemistry and evaluate it against observations and other tropospheric chemistry models. In particular, from a climate forcing perspective, present-day observed surface methane concentrations and tropospheric ozone concentrations are reproduced very well by the model, thereby making it suitable for long centennial integrations as well as studies of biogeochemical feedbacks. Results from both historical and future simulations with UKCA tropospheric chemistry are presented. Future projections of tropospheric ozone vary with the Representative Concentration Pathway (RCP). In RCP2.6, for example, tropospheric ozone increases up to 2010 and then declines by 13% of its year-2000 global mean by the end of the century. In RCP8.5, tropospheric ozone continues to steadily rise throughout the 21st century, with methane being the main driving factor. Finally, we highlight aspects of the UKCA model which are undergoing and/or have undergone recent developments and are suitable for inclusion in a next-generation Earth System Model. [ABSTRACT FROM AUTHOR]

Published
2013
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150. Air quality modelling using the Met Office Unified Model: model description and initial evaluation.

Author

Savage, N. H., Agnew, P., Davis, L. S., Ordóñez, C., Thorpe, R., Johnson, C. E., O'Connor, F. M., and Dalvi, M.

Subjects
MATHEMATICAL models of air quality, ENVIRONMENTAL quality, WEATHER forecasting, OZONE, EMISSION standards
Abstract

The article discusses on-line air quality model Air Quality in the Unified Model (AQUM), which is a limited area forecast configuration of the Met Office Unified Model. It also discusses methods applied to evaluate the performance of the forecast system. It also compares AQUM ozone forecasts with other forecasting systems and discusses relative sources of error in air quality modelling.

Published
2012
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