Nonlinearity in ENSO-Precipitation-Terrestrial Water Storage Relationships

Recent studies examining the relationships between ENSO, precipitation, and terrestrial water storage (TWS) have often assumed linearity. Here we show this assumption, in instances, to be simplistic, mainly due to the threshold behavior of TWS, identified in seasonal mean time series from both remote sensing observations and coupled earth system model simulations. We explore the causes and the spatio-temporal structure of the deviations from linearity between ENSO-TWS teleconnections, as well as Precipitation-TWS relationships. Results suggest disproportionate variance in TWS in winter monsoon regions. By applying cluster analysis techniques, we then provide distinct regimes of teleconnections based on basin hydrology and variability in ENSO events in terms of their timing, frequency, duration, and intensity, and present the typical recovery times associated with each regime. Implications for global mean sea level are discussed.