The roles of atmospheric wind and entrained water temperature (Te) in the second-year cooling of the 2010–12 La Niña event
Tóm tắt
An intermediate coupled model (ICM) yields a successful real-time prediction of the sea surface temperature (SST) evolution in the tropical Pacific during the 2010–12 La Niña event, whereas many other coupled models fail. It was previously identified that the thermocline effect on the SST (including vertical advection and mixing), as represented by water temperature entrained into the mixed layer (Te) and its relationship with the thermocline fluctuation, is an important factor that affects the second-year cooling in mid-late 2011. Because atmospheric wind forcing is also important to ENSO processes, its role is investigated in this study within the context of real-time prediction of the 2010–12 La Niña event using the ICM in which wind stress anomalies are calculated using an empirical model as a response to SST anomalies. An easterly wind anomaly is observed to persist over the western-central Pacific during 2010–11, which acts to sustain a horse shoe-like Te pattern connecting large negative subsurface thermal anomalies in the central-eastern regions off and on the equator. Sensitivity experiments are conducted using the ICM to demonstrate how its SST predictions are directly affected by the intensity of wind forcing. The second-year cooling in 2011 is not predicted to occur in the ICM if the easterly wind anomaly intensity is weakly represented below certain levels; instead, a surface warming can emerge in 2011, with weak SST variability. The results of the current study indicate that the intensity of interannual wind forcing is equally important to SST evolution during 2010–11 compared with that of the thermocline effect. To correctly predict the observed La Niña conditions in the fall of 2011, the ICM needs to adequately represent the intensity of both the wind forcing and the thermocline effects.
Tài liệu tham khảo
Barnett TP, Latif M, Graham N, Flugel M, Pazan S, White W (1993) ENSO and ENSO-related predictability. Part I: prediction of equatorial Pacific sea surface temperature with a hybrid coupled ocean–atmosphere model. J Clim 6:1545–1566
Barnston AG, Tippett MK, L’Heureux ML, Li S, DeWitt DG (2012) Skill of real-time seasonal ENSO model predictions during 2002–11: is our capability increasing? Bull Am Meteorol Soc 93:631–651
Battisti DS, Hirst AC (1989) Interannual variability in the tropical atmosphere-ocean system: influences of the basic state, ocean geometry and nonlinearity. J Atmos Sci 46:1687–1712
Bjerknes J (1969) Atmospheric teleconnections from the equatorial Pacific. Mon Weather Rev 97:163–172
Cane MA, Zebiak SE, Dolan SC (1986) Experimental forecast of El Niño. Nature 321:827–832
Chen D, Zebiak SE, Busalacchi AJ, Cane MA (1995) An improved procedure for El Niño forecasting: implications for predictability. Science 269:1699–1702
DiNezio PN, Deser C (2014) Nonlinear controls on the persistence of La Niña. J Clim 27:7335–7355. doi:10.1175/JCLI-D-14-00033.1
Feng L, Zhang RH, Wang Z, Chen X (2015) Processes leading to the second-year cooling of the 2010–12 La Niña event, diagnosed from GODAS. Adv Atmos Sci 32:424–438. doi:10.1007/s00376-014-4012-8
Gu D, Philander SGH (1997) Interdecadal climate fluctuations that depend on exchanges between the tropics and extratropics. Science 275(5301):805–807
Hu ZZ, Kumar A, Xue Y et al (2014) Why were some La Niñas followed by another La Niña? Clim Dyn 42(3):1029–1042
Ji M, Leetmaa A, Kousky VE (1996) Coupled model forecasts of ENSO during the 1980 and 1990s at the National Meteorological Center. J Clim 9:3105–3120
Jin F-F (1997) An equatorial ocean recharge paradigm for ENSO. Part I: conceptual model. J Atmos Sci 54:811–829
Jin F-F, An S (1999) Thermocline and zonal advective feedbacks within the equatorial ocean recharge oscillator model for ENSO. Geophys Res Lett 26(19):2989–2992. doi:10.1029/1999GL002297
Kalnay E et al (1996) The NMC/NCAR reanalysis project. Bull Am Meteorol Soc 77:437–471
Keenlyside N, Kleeman R (2002) On the annual cycle of the zonal currents in the equatorial Pacific. J Geophys Res. doi:10.1029/2000JC0007111
Kirtman B, Fan Y, Schneider EK (2002) The COLA global coupled and anomaly coupled ocean–atmosphere GCM. J Clim 15:2301–2320
Latif M et al (1998) A review of the predictability and prediction of ENSO. J Geophys Res 103:14375–14393
Lee S-K, DiNezio PN, Chung E-S, Yeh S-W, Wittenberg AT, Wang C (2014) Spring persistence, transition, and resurgence of El Niño. Geophys Res Lett 41:8578–8585. doi:10.1002/2014GL062484
Luo JJ, Masson S, Behera S, Shingu S, Yamagata T (2005) Seasonal climate predictability in a coupled OAGCM using a different approach for ensemble Forecasts. J Clim 18:4474–4497
McCreary JP (1981) A linear stratified ocean model of the equatorial undercurrent. Philos Trans R Soc (Lond) 298:603–635
McPhaden MJ, Zebiak SE, Glantz MH (2006) ENSO as an integrating concept in Earth Science. Science 314:1740–1745
Meinen CS, McPhaden MJ (2000) Observations of warm water volume changes in the equatorial Pacific and their relationship to El Niño and La Niña. J Clim 13:3551–3559
Okumura M, Deser C (2010) Asymmetry in the duration of El Niño and La Niña. J Clim 23:5826–5843. doi:10.1175/2010JCLI3592.1
Picaut J, Masia F, du Penhoat Y (1997) An advective-reflective conceptual model for the oscillatory nature of the ENS0. Science 227:663–666
Reynolds RW, Smith TM (1994) Improved global sea surface temperature analyses using optimum interpolation. J Clim 7(6):929–948
Reynolds RW, Rayner NA, Smith TM, Stokes DC, Wang W (2002) An improved in situ and satellite SST analysis for climate. J Clim 15:1609–1625
Saha S et al (2006) The NCEP climate forecast system. J Clim 19:3483–3517
Schopf and Suarez (1988) Vacillations in a coupled ocean–atmosphere model. J Atmos Sci 45:549–566
Stockdale TN et al (2011) ECMWF seasonal forecast system 3 and its prediction of sea surface temperature. Clim Dyn 37:455–471. doi:10.1007/s00382-010-0947-3
Wang C (2001) A unified oscillator model for the El Niño-southern oscillation. J Clim 14:98–115
Wang C, Picaut J (2004) Understanding ENSO physics—a review. In: Wang C, Xie S-P, Carton JA (eds) Earth’s climate: the ocean–atmosphere interaction, vol 147. AGU Geophysical Monograph Series, Washington, DC, pp 21–48
Wang C, Weisberg RH, Virmani JI (1999) Western Pacific interannual variability associated with El Niño-southern oscillation. J Geophys Res 104(C3):5131–5149
Wang W, Chen M, Kumar A (2010) An assessment of the CFS real-time seasonal forecasts. Weather Forecast 25:950–969
Weisberg RH, Wang C (1997) A western Pacific oscillator paradigm for the El Niño-southern oscillation. Geophys Res Lett 24:779–782
Zebiak SE, Cane MA (1987) A model El Niño/southern oscillation. Mon Weather Rev 115:2262–2278
Zhang R-H, Zebiak SE, Kleeman R et al (2003) A new intermediate coupled model for El Niño simulation and prediction. Geophys Res Lett 30(19):2012. doi:10.1029/2003GL018010
Zhang R-H, Kleeman R, Zebiak SE, Keenlyside N, Raynaud S (2005a) An empirical parameterization of subsurface entrainment temperature for improved SST simulations in an intermediate ocean model. J Clim 18:350–371
Zhang R-H, Zebiak SE, Kleeman R, Keenlyside N (2005b) Retrospective El Niño forecast using an improved intermediate coupled model. Mon Weather Rev 133:2777–2802
Zhang R-H, Busalacchi AJ, DeWitt DG (2008) The roles of atmospheric stochastic forcing (SF) and oceanic entrainment temperature (Te) in decadal modulation of ENSO. J Clim 21:674–704
Zhang R-H, Zheng F, Zhu J, Wang ZG (2013) A successful real-time forecast of the 2010–11 La Niña event. Sci Rep 3:1108. doi:10.1038/srep01108
Zhang R-H, Gao C (2015) Role of subsurface entrainment temperature (Te) in the onset of El Niño events, as revealed in an intermediate coupled model. Clim Dyn. doi:10.1007/s00382-015-2655-5
Zhang R-H, Gao C, Kang X, Zhi H, Wang Z, Feng L (2015) ENSO modulations due to interannual variability of freshwater forcing and ocean biology-induced heating in the tropical Pacific. Sci Rep 5:18506. doi:10.1038/srep18506
Zheng F, Zhu J, Zhang R-H, Zhou G-Q (2006) Ensemble hindcasts of SST anomalies in the tropical Pacific using an intermediate coupled model. Geophys Res Lett 33:L19604. doi:10.1029/2006GL026994
Zhu J, Huang B, Marx L, Kinter JL III, Balmaseda MA, Zhang R-H, Hu ZZ (2012) Ensemble ENSO hindcasts initialized from multiple ocean analyses. Geophys Res Lett 39(9). doi:10.1029/2012GL051503
Zhu J, Huang B, Zhang R-H et al (2014) Salinity anomaly as a trigger for ENSO events. Sci Rep 4:6821. doi:10.1038/srep06821