Global Mean Sea Level Variation On Interannual-Decadal Timescales: Climatic Connections

We investigate the influences of the climatic oscillations on global mean sea level (GMSL) on interannual-decadal timescales. We conduct correlation analyses on the GMSL-ID time series, which is obtained upon removing numerically the long-term trend and seasonal variations from satellite radar altimeter data since 1992, with several climatic oscillations represented by their respective meteorological indices, including El Niño-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), Atlantic Multidecadal Oscillation (AMO), Arctic Oscillation (AO), Antarctic Oscillation (AAO). From the time-domain correlation and frequency-domain coherence, we find: (i) High correlation between GMSL and ENSO on timescales longer than 1.5 years, especially w.r.t. the Central-Pacific type of El Niño, evidently related to changes in dynamics of the ocean mixed layer and in land-sea distribution of precipitation. (ii) Moderate correlations of GMSL with PDO and AMO, respectively on timescales of over 4 years and 2-10 years, where AMO’s correlation peaks at 8 months earlier in phase than GMSL. (iii) Weak correlation of GMSL with AO implying exchanges of the Arctic water with other oceans even though the altimetry data do not include Arctic sea,. (iv) Practically no correlation between GMSL and AAO. Finally, we least-squares fit the above five indexes to GMSL to assess the relative contribution of each oscillation in causing the interannual GMSL variations, which would lead to a better understanding of the GMSL under the on-going climate changes.