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Roxana C. Wajsowicz

spring and early summer when the coupling strength is maximal, has been explained using linear dynamics and a simple delayed oscillator mechanism by Tziperman et al. (1998) and is illustrated in Fig. 3c . Assuming coupling strength is proportional to thermocline depth, then westerly anomalies generated in boreal spring when the ENSO event is weak generate weak upwelling westward propagating long Rossby waves (LRWs) and weak downwelling eastward propagating equatorial Kelvin waves (EKWs). The LRWs

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Bohua Huang and J. Shukla

. (2002) suggested that the tropical Indian Ocean mode leads the subtropical fluctuations in the southern Indian Ocean. They speculate that the Sumatra SST variability may excite atmospheric waves that pass over the subtropical ocean and generate SST anomalies in local summer. In our simulations, the tropical mode produces SST anomalies in the subtropical ocean during austral summer (e.g., Fig. 11c ) consistent with Xie et al.’s (2002) results. On the other hand, the subtropical SST anomalies can

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Rui-Jin Hu and J. Stuart Godfrey

Indian Ocean coastline shape, and it was forced with observed annual mean winds and “swamp temperature” T swamp . As explained below, T swamp is the value of SST, for given atmospheric variables, for which net surface heat flux is zero. In a second experiment seasonality of T swamp (only) was allowed for; and in a third, the observed seasonal cycle of variations was added to the annual means of both T swamp and wind stress. In these three experiments, the same rather coarse vertical grid

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J. C. Hermes, C. J. C. Reason, and J. R. E. Lutjeharms

the central and eastern Indian Ocean tend to prevent propagation of the annual-period Rossby wave from the eastern south Indian Ocean ( Matano et al. 1998 , 1999 ). Biastoch et al. (1999) suggested that an increase in flow through the Mozambique Channel derived from the Agulhas as Primitive Equations (AGAPE) model during austral winter was due to increased Ekman transport when the south Indian Ocean anticyclone is situated farther to the north. By tracing the model tropical surface water, they

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Jean Philippe Duvel and Jérôme Vialard

using the Reynolds and Smith (1994) weekly SST analyses gave far smaller SST variability related to the convective ISV (e.g., Jones et al. 1998 ; Shinoda et al. 1998 ; Woolnough et al. 2000 ). This is due in part to the screening effect of the cloudiness that prevents the estimation of the SST by satellite measurements in the infrared atmospheric window. This screening effect likely reduces the estimated ISV of the SST by masking the surface cooling during convective events. During winter 1999

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Lisan Yu, Xiangze Jin, and Robert A. Weller

between the surface heat flux products ( Bony et al. 1997 ; Sun et al. 2003 ; Brunke et al. 2003 ; Toole et al. 2004 ; Curry et al. 2004 ). For instance, the buoy measurements of Weller et al. (1998) taken during the Arabian Sea Experiment in 1994–95 showed a net heat gain of 60.3 W m −2 , while the Q net produced from the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis had a net heat loss of −4.5 W m −2 : the mean differences

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Qian Song, Gabriel A. Vecchi, and Anthony J. Rosati

/eastern tropical Pacific (e.g., Harrison and Larkin 1998 ). These basin-wide ENSO-driven Indian Ocean SSTAs can be partially attributed to anomalous air–sea enthalpy and radiative fluxes, remotely forced by ENSO through an “atmospheric bridge” ( Klein et al. 1999 ). However, the lack of equatorial upwelling does not preclude coupled dynamics arising from Bjerknes-type feedbacks in the Indian Ocean, as there is upwelling along the coast of Somalia (boreal summer), off of Java–Sumatra (May–November), and in the

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J. Stuart Godfrey, Rui-Jin Hu, Andreas Schiller, and R. Fiedler

patterns. Despite these large intermodel differences the climatologies suggest that the AMNHFs from the OGCMs are rather similar, but nearly all of them seriously underestimate the observed net heat flux. In an unpublished work, referred to below as UW, we and others explored long-term mean northward heat transports in a coarse grid global OGCM. In one experiment (UW − Control) the observed seasonality of all atmospheric forcing variables was retained. In the other (UW − 12MRM), the wind stress (only

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Gary Meyers, Peter McIntosh, Lidia Pigot, and Mike Pook

the ocean and atmosphere (upwelling and wind) in the cold tongue region, while the transition from El Niño to La Niña (or vice versa) is controlled by a delayed negative feedback transmitted in the depth of the thermocline ( Kessler 2002 ; McPhaden 2004 ). Upwelling is the oceanic process that links the slow physics of thermocline dynamics (Rossby and Kelvin waves) to SST, giving long persistence and predictability to the climate system. The strength of upwelling in the central and eastern

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Tommy G. Jensen

associated equatorial zonal wind stress, anomalous rainfall over East Africa, and its correlation to global atmospheric anomalies (e.g., Saji and Yamagata 2003a ; Lau and Nath 2004 ; Shinoda and Alexander 2004 ). Studies of regional changes in the Indian Ocean general circulation are few and focus on the upwelling off Sumatra and the thermal structure along the equator (e.g., Murtugudde et al. 2000 ; Vinayachandran et al. 2002 ; Feng and Meyers 2003 ). Recently, Haugen et al. (2002) and

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