LAUSR

A method for computing instantaneous rate of the Antarctica ice sheet (AIS) mass changes is proposed in this letter. The method combines the ensemble empirical mode decomposition (EEMD) and cubic spline smoothing (CSS). First, EEMD is used to extract the nonlinear trend from the time series of the AIS mass changes observed by satellite gravimetry, and then CSS is used to fit the nonlinear trend. The first-order derivative from the fit curve is the instantaneous rate. Compared with the linear rate, the instantaneous rate improves the temporal resolution of mass change rate. The instantaneous rate reveals the complex behavior of the AIS mass changes; at regional scale, mass changes show negative rate for one period and positive rate for another. This important information is masked by the linear rate which only suggests an overall increasing or decreasing trend. The instantaneous rate promotes our understanding of the mass changes in the AIS and shows implication for detecting the anomalous changes in climate.