Amplitude Modulation of Seasonal Variability in Terrestrial Water Storage

Abstract Variability in climate and weather in many land regions is dominated by a seasonal cycle that is typically defined by as a stable, repeated pattern. Defining the annual cycle as strictly stationary, however, precludes the possibility of changes in its amplitude from one year to the next. In this study, we target and extract the modulated annual cycle in terrestrial water storage with a statistical analysis technique specifically suited to this application. We estimate the amplitude modulation of the annual cycle in terrestrial water storage in order to assess the drivers of strength of the seasonal water cycle from year to year and identify trends in the amplitude that are persistent over the 13‐year record used here. We find that climate variability is found to be one of the dominant drivers of the strength of the annual cycle in terrestrial water storage, with El Niño‐Southern Oscillation found to play a particularly significant role, as identified in previous studies.