The Niño Dipole Index

The effect of ENSO on global atmospheric weather patterns arises through a redistribution of tropical Pacific convection. This paper explores the hypothesis that a primary ENSO index that represents the gradient of tropical Pacific sea surface temperatures will be a more robust indicator of ENSO and its global influence than temperatures in a single ocean patch. We preserve the convention of computing SST averages over patches of ocean and conduct a comprehensive search of candidate box locations and dimensions. We assume that the "best" index will have a high correlation with ENSO-related global precipitation modes in all seasons. We evaluate the sensitivity of box choice to precipitation data set, length of data record, SST data set, and data preprocessing steps. We then apply the same box definitions to CMIP model simulations and test whether the diversity of model ENSO responses can be understood in the context of how ENSO is measured in the first place.