Title: 1 Timing of Subsurface Heat Magnitude for the Growth of El Niño Events 2 3 Authors: 4

28 29 The subsurface heat buildup in the western tropical Pacific and the recharge phase in 30 equatorial heat content are intrinsic elements of El Niño-Southern Oscillation, leading to changes in 31 zonal wind stress, sea surface temperature and thermocline tilt that characterize the growing and 32 mature phases of El Niño (EN) events. Here we use ocean and atmosphere reanalyses and numerical 33 simulations to study the impact on subsequent EN episodes of a sudden discharge or recharge in 34 ocean heat content during these phases. We found that the timing and magnitude of the events are 35 not substantially affected by the phase at which a sudden recharge is prescribed, but instead they 36 largely depend on the phase at which a major discharge is imposed. The different response to the 37 phase of recharges and discharges confirms the non-linear relationship between the intensity of the 38 subsurface heat buildup and the magnitude and timing of subsequent EN episodes. 39 40 4