Fig. 1. Leading modes of detrended Antarctic mass change . Maps show the orthogonal functions for the two leading modes of detrended GRACE data (a and d ). The respective principal components are shown (c and f ) along with detrended SAMΣ and (unlagged and lagged) Niño3.4Σindices, respectively. The regression of RACMO2.3p2_ANT surface mass balance (SMB) anomalies against GRACE PC1 and PC2 are shown inb and e , respectively.