Ocean Science www.ocean-sci.net 1812-0784 1812-0792 6 2 2010 10.5194/os-6-441-2010 http://www.ocean-sci.net/6/441/2010/ http://www.ocean-sci.net/6/441/2010/os-6-441-2010.html http://www.ocean-sci.net/6/441/2010/os-6-441-2010.pdf 441 459 2010-04-20 The role of atmosphere and ocean physical processes in ENSO in a perturbed physics coupled climate model S. Y. Philip M. Collins matthew.collins@metoffice.gov.uk G. J. van Oldenborgh B. J. J. M. van den Hurk Royal Netherlands Institute of Meteorology, De Bilt, The Netherlands Met Office Hadley Centre, Exeter, UK Institute for Marine and Atmospheric Research, Utrecht University, Utrecht, The Netherlands We examine the behaviour of the El Niño – Southern Oscillation (ENSO) in an ensemble of global climate model simulations with perturbations to parameters in the atmosphere and ocean components respectively. The influence of the uncertainty in these parametrisations on ENSO are investigated systematically. The ensemble exhibits a range of different ENSO behaviour in terms of the amplitude and spatial structure of the sea surface temperature (SST) variability. The nature of the individual feedbacks that operate within the ENSO system are diagnosed using an Intermediate Complexity Model (ICM), which has been used previously to examine the diverse ENSO behaviour of the CMIP3 multi-model ensemble. Unlike in that case, the ENSO in these perturbed physics experiments is not principally controlled by variations in the mean climate state. Rather the parameter perturbations influence the ENSO characteristics by modifying the coupling feedbacks within the cycle. The associated feedbacks that contribute most to the ensemble variations are the response of SST to local wind variability and damping, followed by the response of SST to thermocline anomalies and the response of the zonal wind stress to those SST anomalies. Atmospheric noise amplitudes and oceanic processes play a relatively minor role. AchutaRao, K. and Sperber, K R.: Simulation of the El Niõ Southern Oscillation: Results from the Coupled Model Intercomparison Project, Clim. Dynam., 19, 191–209, 2002. AchutaRao, K. and Sperber, K R.: ENSO simulation in coupled ocean-atmosphere models: are the current models better?, Clim. Dynam., 27, 1–15, 2006. Annan, J D., Hargreaves, J C., Ohgaito, R., Abe-Ouchi, A., and Emori, S.: Efficiently constraining climate sensitivity with ensembles of paleoclimate simulations, Scientific on-line letters on the atmosphere, 1, 181–184, 2005. Burgers, G., Balmaseda, M A., Vossepoel, F C., van Oldenborgh, G J., and van Leeuwen, P J.: Balanced Ocean-Data Assimilation near the Equator, J. Phys.\ Oceanogr., 32, 2509–2529, 2002. Burgers, G J H. and van Oldenborgh, G J.: On the impact of local feedbacks in the Central Pacific on the ENSO cycle, J. Climate, 16, 2396–2407, 2003. Capotondi, A., Wittenberg, A., and Masina, S.: Spatial and temporal structure of tropical Pacific interannual variability in 20th century coupled simulations, Ocean Model., 15, 274–298, 2006. Clarke, A J.: Why Are Surface Equatorial ENSO Winds Anomalously Westerly under Anomalous Large-Scale Convection?, J. Climate, 7, 1623–1627, 1994. Collins, M.: Ensembles and probabilities: a new era in the prediction of climate change, Philosophical Transactions of the Royal Society A, 365(1857), 1957–1970, 2007. Collins, M., Tett, S. F B., and Cooper, C.: The internal climate variability of HadCM3, a version of the Hadley Centre coupled model without flux adjustments, Clim. Dynam., 17, 61–81, 2001. Collins, M., Booth, B., Harris, G., Murphy, J., Sexton, D., and Webb, M.: Towards Quantifying Uncertainty in Transient Climate Change, Clim. Dynam., 27(2–3), 127–147, 2006. Dewitte, B., Cibot, C., Périgaud, C., An, S I., and Terray, L.: Interaction between Near–Annual and ENSO Modes in a CGCM Simulation: Role of the Equatorial Background Mean State, J. Climate, 20, 1035–1052, 2007. Neelin, J D. and Dijkstra, H A.: Ocean–atmosphere interation and the tropical climatology. Part 1: The dangers of flux correction, J. Climate, 8, 1325–1342, 1995. Fedorov, A V. and Philander, S G.: A stability analysis of tropical ocean-atmosphere interactions: bridging measurements and theory for El Niño, J. Climate, 14, 3086–3101, 2001. Gill, A E.: Some simple solutions for heat induced tropical circulation, Q. J. Roy. Meteor. Soc., 106, 447–462, 1980. Gill, A E.: Atmosphere–Ocean Dynamics, Academic Press, Orlando, 662 pp., 1982. Gordon, C., Cooper, C., Senior, C. A., Banks, H., Gregory, J. M., Johns, T C., Mitchell, J. F B., and Ingram, W. R.: The simulation of SST, sea ice extents and ocean heat transport in a version of the Hadley Centre coupled model without flux adjustments, Clim. Dynam., 16, 147–168, 2000. Guilyardi, E.: El Niño – mean state – seasonal cycle interactions in a multi-model ensemble, Clim. Dynam., 26, 329–348, 2006. Guilyardi, E., Wittenberg, A., Fedorov, A., Collins, M., Wang, C., Capotondi, A., van Oldenborgh,~G. J., and Stockdale, T.: Understanding El Niño in Ocean-Atmosphere General Circulation Models: progress and challenges, B.\ Am. Meteorol. Soc., 90, 325–340, 2009. Harris, G., Sexton, D., Booth, B., Collins, M., Murphy, J., and Webb, M.: Frequency Distributions of Transient Regional Climate Change from Perturbed Physics Ensembles of General Circulation Model Simulations, Clim. Dynam., 27, 357–375, 2006. Kirtman, B.: Oceanic Rossby wave dynamics and the ENSO period in a coupled model, J. Climate, 10, 1690–1704, 1997. Knutti, R., Meehl, G A., Allen, M R., and Stainforth, D A.: Constraining climate sensitivity from the seasonal cycle in surface temperature, J.\ Climate, 19, 4224–4233, 2006. Lin, J. L.: The Double-ITCZ Problem in IPCC AR4 Coupled GCMs: Ocean-Atmosphere Feedback Analysis, J. Climate, 20, 4497–4525, 2007. Lloyd, J., Guilyardi, E., Weller, H., and Slingo, J.: The Role of Atmosphere Feedbacks During ENSO in the CMIP3 Models, Atmos. Sci. Lett., 10(3), 170–176, 2009. Merryfield, W J.: Changes in ENSO under $CO_2$ doubling in the IPCC AR4 coupled climate models, J. Climate, 19, 4009–4027, 2006. Moore, B., Gates, W., L. J., M., and Underdal, A.: Advancing our understanding, in: Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Houghton, J. T., Ding, Y., Griggs, D. J., Noguer, M., van der Linden, P. J., Dai. X., Maskell, K., and Johnson, C. A., Cambridge University Press, 2001. Murphy, J M., Sexton, D. M H., Barnett, D N., Jones, G S., Webb, M J., Collins, M., and Stainforth, D A.: Quantification of modelling uncertainties in a large ensemble of climate change simulations, Nature, 430, 768–772, 2004. Niehörster, F., Spangehl, T., Fast, I., and Cubasch, U.: Quantification of model uncertainties: Parameter sensitivities of the coupled model ECHO-G with middle atmosphere, Vol 8, EGU06-A-08526, 2006. Philip, S. and van Oldenborgh, G J.: Shifts in ENSO coupling processes under global warming, Geophys. Res. Lett., 33, L11704, doi:10.1029/2006GL026196, 2006. Philip, S. and van Oldenborgh, G J.: Significant atmospheric nonlinearities in the ENSO cycle, J. Climate, 22, 4014–4028, 2009. Philip, S Y. and van Oldenborgh, G J.: Atmospheric properties and ENSO: models versus observations, Clim. Dynam., doi:10.1007/s00382-009-0579-7, in press, 2010. Piani, C., Frame D J., Stainforth, D A., and Allen, M R.: Constraints on climate change from a multi-thousand member ensemble of simulations, Geophys. Res. Lett., 32, L23825, doi:10.1029/2005GL024452, 2005. Reynolds, R W., Rayner, N A., Smith, T M., Stokes, D C., and Wang, W.: An Improved In Situ and Satellite SST Analysis for Climate, J. Climate, 15, 1609–1625, 2002. Rougier, J., Sexton, D., Murphy, J., and Stainforth, D.: Analysing the climate sensitivity of the HadSM3 climate model using ensembles from different but related experiments, J. Climate, 22(13), 3540–3557, doi:10.1175/2008JCLI2533.1, 2009. Sanderson, B., Knutti, R., Aina, T., Christensen, C., Faull, N., Frame, D., Ingram, W., Piani, C., Stainforth, D. A and Stone, D., and Allen, M.: Constraints on Model Response to Greenhouse Gas Forcing and the Role of Subgrid-Scale Processes, J. Climate, 21, 2384–2400, 2008. Sanderson, B M. and Piani, C.: Towards constraining climate sensitivity by linear analysis of feedback patterns in thousands of perturbed-physics gcm simulations, Clim. Dynam., 30, 175–190, 2007. Schneider~von Deimling, T., Held, H., Ganopolski, A., and Rahmstorf, S.: Climate sensitivity estimated from ensemble simulations of glacial climates, Clim. Dynam., 27, 149–163, 2006. Spencer, H., R. Sutton and J. M. Slingo: El Niño in a Coupled Climate Model: Sensitivity to Changes in Mean State Induced by Heat Flux and Wind Stress Corrections, J. Climate, 20, 2273–2298, 2007. Stainforth, D A., Aina, T., Christensen, C., Collins, M., Faull, N., Frame, D J., Kettleborough, J A., Knight, S., Martin, A., Murphy, J M., Piani, C., Sexton, D., Smith, L A., Spicer, R A., Thorpe, A J., and Allen, M R.: Uncertainty in predictions of the climate response to rising levels of greenhouse gases, Nature, 433, 403–406, 2005. Timmermann, A., Okumura, Y., An, S.-I., Clement, A., Dong, B., Guilyardi, E., Hu, A., Jungclaus, J., Krebs, U., Renold, M., Stocker, T. F., Stouffer, R. J., Sutton, R., Xie, S.-P., and Yin, J.: The influence of a weakening of the Atlantic meridional overturning circulation on ENSO, J. Climate, 20, 4899–4919, 2007. Toniazzo, T.: Properties of the El Niño Southern Oscillation in different equilibrium climates with the HadCM3 model, J. Climate, 19, 4854–4876, 2006. Toniazzo, T., Collins, M., and Brown, J.: The variation of ENSO characteristics associated with atmospheric parameter perturbations in a coupled model, Clim. Dynam., 30, 643–656, 2008. van Oldenborgh, G. J., Philip, S. Y., and Collins, M: El Niño in a changing climate: a multi-model study, Ocean Sci., 1, 81–95, 2005. Webb, M J., Senior, C A., Sexton, D. M H., Ingram, W J., Williams, K D., Ringer, M A., McAvaney, B J., Colman, R., Soden, B J., Gudgel, R., Knutson, T., Emori, S., Ogura, T., Tsushima, Y., Andronova, N., Li, B., Musat, I., Bony, S., and Taylor, K E.: On the contribution of local feedback mechanisms to the range of climate sensitivity in two GCM ensembles, Clim. Dynam., 27, 17–18, 2006. Zelle, H., Van~Oldenborgh, G J., Burgers, G., and Dijkstra, H A.: El Niño and Greenhouse Warming: Results from Ensemble Simulations with the NCAR CCSM, J. Climate, 18, 4683–4669, 2005.