Large-Ensemble Recharge Oscillator Simulation Data

README: RO Parameter Ensemble Simulation DataVersion 2, April 13, 2026 Author: Sooman Han ([e-mail]) 1. Description This dataset contains ensemble simulations of a Recharge Oscillator (RO) model designed to quantify the magnitude of internal variability, estimate the number of ensemble members required to suppress that variability, and assess whether forced changes can be detected in its presence. The numerical code used for these simulations was previously archived as “ENSO Recharge Oscillator: Parameter Sweep Simulation Code,” which supports the study “Realistic ENSO Dynamics Requires a Damped Nonlinear Recharge Oscillator,” available at: https://zenodo.org/records/16888262 The dataset includes the following simulation cases: - Case 1: fixed parameters- Case 2: a 20% per century increase in R_0- Case 3: a 20% per century increase in F_1 Each case contains time series of temperature (T) and thermocline depth (h) anomalies for 5,000 ensemble members. Each ensemble member spans 3,600 months (300 years), with output saved at monthly cadence. The simulations were integrated using the Euler–Maruyama scheme with a timestep of 0.01 second. For further details of the model formulation, see Han et al. (2026). 2. File Description The Case 1 folder includes: simul_{simul_num}.txt, where simul_num = 0000, 0001, ..., 4999 This file contains the simulated time series of T and h. Format:- 2 columns: T, h std_moving_0040_{simul_num}_multiplicative_LR-F.txtskew_moving_0040_{simul_num}_multiplicative_LR-F.txtlag_moving_0040_{simul_num}_multiplicative_LR-F.txtfitted_parameters_moving_0040_{simul_num}_multiplicative_LR-F.txt These files contain 40-year moving-window diagnostics of standard deviation, skewness, and ENSO period identified from the first minimum of the autocorrelation function, along with fitted RO model parameters over the 300-year simulations. error_cf090_r{error}_{moving_window}y_0100_multiplicative_LR-F.txt This file gives the required ensemble size needed to suppress internal variability for the three ENSO metrics within a prescribed relative error level for a given moving-window length. error = 025, 024, ..., 005; relative errormoving_window = 020, 040, 060; moving-window length param_error_cf090_r{error}_{moving_window}y_0100_multiplicative_LR-F.txt This file is similar to error_cf090_r{error}_{moving_window}y_0100_multiplicative_LR-F.txt, but for fitted model parameters. The Case 2 and Case 3 folders are similar to the Case 1 folder, but they do not containerror_cf090_r{error}_{moving_window}y_0100_multiplicative_LR-F.txtorparam_error_cf090_r{error}_{moving_window}y_0100_multiplicative_LR-F.txt. The obs folder contains:- nino3_HadISST.txt (HadISST Niño-3 index time series)- 40-year moving-window standard deviation, period, and skewness (std_moving_0040_obs.txt, lag_moving_0040_obs.txt, skew_moving_0040_obs.txt)- fitted parameter results (fitted_parameters_moving_0040_obs_multiplicative_LR-F.txt) Plot scripts are provided in the following folders: - fig01_S03_S04- fig02_S05- fig03_S06- figS01- figS02 3. Reference Han, S., A. V. Fedorov, and J. Vialard, 2026: Realistic ENSO Dynamics Requires a Damped Nonlinear Recharge Oscillator. Journal of Climate, 39(1), 77–101. https://doi.org/10.1175/JCLI-D-25-0250.1