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Scaife, A. A.
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- PublicationRestrictedSimulations of anthropogenic change in the strength of the Brewer–Dobson circulation(2006)
; ; ; ; ; ; ; ; ; ; ; ; ;Butchart, N.; Met Office, FitzRoy Road, ;Scaife, A. A.; Hadley Centre, Met Office, ;Bourqui, M.; Department of Meteorology, University of Reading, Reading, UK ;de Grandpre, J.; McGill University, Montreal, Canada ;Hare, S. H. E.; Department of Meteorology, University of Reading, Reading, UK ;Kettleborough, J.; Rutherford Laboratory, British Atmospheric Data Centre, ;Langematz, U.; Freie Universita¨ t of Berlin, Berlin, Germany ;Manzini, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Sassi, F.; National Center for Atmospheric Research,Boulder, CO, USA ;Shibata, K.; Meteorological Research Institute, Tsukuba, Japan ;Shindell, D.; NASA-Goddard Institute for Space Studies, New York, USA ;Sigmond, M.; University of Toronto, Toronto, Canada; ; ; ; ; ; ; ; ; ; ; The effect of climate change on the Brewer– Dobson circulation and, in particular, the large-scale seasonal-mean transport between the troposphere and stratosphere is compared in a number of middle atmosphere general circulation models. All the models reproduce the observed upwelling across the tropical tropopause balanced by downwelling in the extra tropics, though the seasonal cycle in upwelling in some models is more semi-annual than annual. All the models also consistently predict an increase in the mass exchange rate in response to growing greenhouse gas concentrations, irrespective of whether or not the model includes interactive ozone chemistry. The mean trend is 11 kt s–1 year–1 or about 2% per decade but varies considerably between models. In all but one of the models the increase in mass exchange occurs throughout the year though, generally, the trend is larger during the boreal winter. On average, more than 60% of the mean mass fluxes can be explained by the EP-flux divergence using the downward control principle. Trends in the annual mean mass fluxes derived from the EP-flux divergence also explain about 60% of the trend in the troposphere-to-stratosphere mass exchange rate when averaged over all the models. Apart from two models the interannual variability in the downward control derived and actual mass fluxes were generally well correlated, for the annual mean.171 26 - PublicationOpen AccessThe CLIVAR C20C Project: Which components of the Asian-Australian monsoon circulation variations are forced and reproducible?(2009-12-12)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Zhou, T. ;Wu, B. ;Scaife, A. ;Bronnimann, S. ;Cherchi, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Feredey, D. ;Folland, C. K. ;Jin, K. E. ;Kinter, J. ;Knight, J. R. ;Kucharski, F. ;Kusunoki, S. ;Lau, N. C. ;Li, L. ;Nath, M. J. ;Nakaegawa, T. ;Navarra, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Pegion, P. ;Rozanov, E. ;Schubert, S. ;Spryshev, P. ;Voldoire, A.. ;Wen, X. ;Yoon, J. H. ;Zeng, N. ; ; ; ;; ; ; ; ; ; ; ; ; ; ; ;; ; ; ; ; ; ; ;A multi-model set of atmospheric simulations forced by historical sea surface temperature (SST) or SSTs plus Greenhouse gases and aerosol forcing agents for the period of 1950–1999 is studied to identify and understand which components of the Asian–Australian monsoon (A–AM) variability are forced and reproducible. The analysis focuses on the summertime monsoon circulations, comparing model results against the observations. The priority of different components of the A–AM circulations in terms of reproducibility is evaluated. Among the subsystems of the wide A–AM, the South Asian monsoon and the Australian monsoon circulations are better reproduced than the others, indicating they are forced and well modeled. The primary driving mechanism comes from the tropical Pacific. The western North Pacific monsoon circulation is also forced and well modeled except with a slightly lower reproducibility due to its delayed response to the eastern tropical Pacific forcing. The simultaneous driving comes from the western Pacific surrounding the maritime continent region. The Indian monsoon circulation has a moderate reproducibility, partly due to its weakened connection to June–July–August SSTs in the equatorial eastern Pacific in recent decades. Among the A–AM subsystems, the East Asian summer monsoon has the lowest reproducibility and is poorly modeled. This is mainly due to the failure of specifying historical SST in capturing the zonal land-sea thermal contrast change across the East Asia. The prescribed tropical Indian Ocean SST changes partly reproduce the meridional wind change over East Asia in several models. For all the A–AM subsystem circulation indices, generally the MME is always the best except for the Indian monsoon and East Asian monsoon circulation indices.177 196