Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 7 2 2007 10.5194/acpd-7-3941-2007 http://www.atmos-chem-phys-discuss.net/7/3941/2007/ http://www.atmos-chem-phys-discuss.net/7/3941/2007/acpd-7-3941-2007.html http://www.atmos-chem-phys-discuss.net/7/3941/2007/acpd-7-3941-2007.pdf 3941 3962 2007-03-22 Volcanic effects on climate: revisiting the mechanisms H.-F. Graf hfg21@cam.ac.uk Q. Li M. A. Giorgetta Centre for Atmospheric Science, University of Cambridge, UK Max-Planck-Institute for Meteorology, Hamburg, Germany The characteristics of planetary wave energy propagation are being compared based on NCEP reanalysis data from 1958 to 2002 between boreal winters after strong volcanic eruptions, non-volcanic winters and episodes of strong polar vortex lasting at least 30 days. It shows that in the volcanically disturbed winters much more planetary wave energy is produced in the troposphere, passes through the lowermost stratosphere and enters the upper stratosphere than in any other times. This is contradicting earlier interpretations and model simulations. Possibly the observed El Ninos coinciding with the three significant eruptions in the second half of the 20th century contributed to the planetary wave energy. In order to produce the observed robust climate anomaly patterns in the lower troposphere, these planetary waves are suggested to be reflected near the stratopause instead of breaking. While a strong polar vortex is observed after volcanic eruptions in the stratosphere and in the troposphere, specific episodes of strong polar vortex regime exhibit much stronger anomalies and different dynamics. Hence it is suggested that the climate effects of volcanic eruptions are not being explained by the excitation of inherent zonal mean variability modes such as Strong Polar Vortex or Northern Annular Mode, but rather is another mode that possibly reflects upon the North Atlantic Oscillation. Andrews, D. G., Holton, J. R., and Leovy, C. B.: Middle Atmosphere Dynamics, Academic Press Inc., 489 pp, 1987. Angell, J. K. and Korshover, J.: Comparison of stratospheric warming following Agung and Chichon., Mon. Weather Rev., 111, 2129–2135, 1983. Bradley, R. S.: The Explosive Volcanic-Eruption Signal in Northern Hemisphere Continental Temperature Records, Climatic Change, 12, 3, 221–243, 1988. Castanheira, J. M., and Graf, H.-F.: North Pacific-North Atlantic relationships under stratospheric control?, J. Geophys. Res., 108, 4036, doi:10.1029/2002JD002754, 2003. Charney, J. G. and Drazin, P. G.: Propagation of planetary-scale disturbances from the lower into the upper atmosphere, J. Geophys. Res., 66, 83–109, 1961. Garcia-Herrera, R., Calvo, N., Garcia, R. R, and Giorgetta, M. A.: Propagation of ENSO temperature signals into the middle atmosphere: A comparison of two general circulation models and ERA-40 reanalysis data, J. Geophys. Res., 111, D06101, doi:10.1029/2005JD006061, 2006 Graf, H.-F.: Arctic radiation deficit and climate variability, Climate Dyn., 7, 19–28, 1992. Graf, H.-F., Kirchner, I., Robock, Q., and Schult, I.: Pinatubo eruption winter climate effects: model versus observations., Clim. Dyn., 9, 81–93, 1993. Groisman, P. Y.: Possible Regional Climate Consequences of the Pinatubo Eruption - an Empirical-Approach, Geophys. Res. Lett., 19, 15, 1603–1606, 1992. Kalnay, E., Kanamitsu, M., Kistler, R., Collins, W., Deaven, D., Gandin, L., Iredell, M., Saha, S., White, G., Woollen, J., Zhu, Y., Chelliah, M., Ebisuzaki, W., Higgins, W., Janowiak, J., Mo, K. C., Ropelewski, C., Wang, J., Leetmaa, A., Reynolds, R., Jenne, R., and Joseph, D.: The NCEP/NCAR 40-year reanalysis project, Bull. Amer. Meteor. Soc., 77, 437–472, 1996. Kelly, P. M., Jones, P. D., and Jia, P. Q.: The spatial response of the climate system to explosive volcanic eruptions, International Journal of Climatology, 16, 5, 537–550, 1996. Kirchner, I., Stenchikov, G. L., Graf, H. F., Robock, A., and Antuna, J. C.: Climate model simulation of winter warming and summer cooling following the 1991 Mount Pinatubo volcanic eruption, J Geophys. Res.-Atmos., 104, D16, 19 039–19 055, 1999. Kodera, K.: Influence of volcanic eruptions on the troposphere through stratospheric dynamical processes in the northern hemisphere winter, J. Geophys. Res., 99, 1273–1282, 1994. Kistler, R., Kalnay, E., Collins, W., Saha, S., White, G., Woollen, J., Chelliah, M., Ebisuzaki, W., Kanamitsu, M., Kousky, V., van den Dool, H., Jenne, R., and Fiorino, M.: The NCEP-NCAR 50-year reanalysis: Monthly means CD-ROM and documentation, Bull. Amer. Meteor. Soc., 82, 247–268, 2001. Li, Q., Graf, H.-F., and Giorgetta, M.: Stationary planetary wave propagation in Northern Hemisphere winter – climatological analysis of the refractive index., Atmos. Chem. Phys., 7, 183–200, 2006. Manzini, E., Giorgetta, M. A., Esch, M., Kornblueh, L., and Roeckner, E: The influence of sea surface temperatures on the northern winter stratosphere: Ensemble simulations with the MAECHAM5 model, J. Climate, 19, 16, 3863–3881, 2006. Mao, J. and Robock, A.: Surface air temperature simulations y AMIP general circulation models: Volcanic and ENSO signals and systematic errors., J. Clim., 11, 1538–1552, 1998. Mass, C. F. and Portman, D. A.: Major volcanic eruptions and climate: A critical evaluation, J. Clim., 2, 566–593, 1989. Matsuno, T.: Vertical propagation of stationary planetary waves in the winter Northern Hemisphere, J. Atmos. Sci., 27, 871–883, 1970. Miller, R. L., Schmidt, G. A., and Shindell, D. T.: Forced annular variations in the 20th century Intergovernmental Panel of Climate Change Fourth Assessment Report models, J. Geophys. Res., 111, D18101, doi:10.1029/2005JD006323, 2006. Perlwitz, J. and Harnik, N.: Observational evidence of a stratospheric influence on the troposphere by planetary wave reflection, J. Climate, 16, 3011–3026, 2003. Perlwitz, J. and Harnik, N.: Downward coupling between the Stratosphere and Troposphere: The relative roles of wave and zonal mean process, J. Climate, 17, 4902-4909, 2004. Robock, A. and Mao, J.: Winter warming from large volcanic eruption, Geophys. Res. Lett., 19, 2405–2408, 1992. Robock, A.: Volcanic eruptions and climate., Rev. Geophys., 38, 191–219, 2000. Sassi, F., Kinnison, D., Boville, B. A., Garcia, R. R., and Roble, R.: Effect of El Nino-Southern Oscillation on the dynamical, thermal, and chemical structure of the middle atmosphere, J. Geophys. Res., 109 (D17), Art. No. D17108 Sep. 14, doi:10.1029/2003/JD004434, 2004. Shindell, D. T., Schmidt, G. A., Miller, R. L., and Rind, D.: Northern Hemisphere winter climate response to greenhouse gas, ozone, solar, and volcanic forcing, J. Geophys. Res., 106, 7193–7210, 2001. Stenchikov, G., Robock, A., Ramaswamy, V., Schwarzkopf, M., Hamilton, K., and Ramachamdran, S.: Arctic Oscillation response to the 1991 Mount Pinatubo eruption: Effectis of volcanic aerosols and ozone depletion, J. Geophy. Res., 107, (D24), 4803, doi:10.1029/2002JD002090, 2002. Stenchikov, G., Hamilton, K., Stouffer, R. J., Robock, A., Ramaswamy, V., Santer, B., and Graf, H.-F.: Climate impacts of volcanic eruptions in the IPCC AR4 climate models, J. Geophys. Res., 111, D07107, doi:10.1029/2005JD006286, 2006.