Interdecadal Changes in Global Ocean Evaporation: Dynamic Factors Analysis

Using the dynamical adjustment method, variations of ocean evaporation and its dynamically induced and radiative forced components from 1958 to 2016 are studied based on the Objectively Analyzed Air-sea Fluxes (OAFlux) dataset. It is found that ocean evaporation and its dynamically induced components have consistent interdecadal changes, especially the transitions that occurred in the late 1970s and 1990s. Further analysis shows that the major dynamic factors that affect ocean evaporation are the Pacific-North America teleconnection (PNA), the Arctic Oscillation (AO), the North Atlantic Oscillation (NAO), El Niño-Southern Oscillation (ENSO) and Aleutian Low (AL). The Pacific Decadal Oscillation (PDO) also has certain impacts. Among these factors, the transition in the 1970s is closely related to the PNA, PDO, ENSO and AL, while the transition in the 1990s is also related to NAO. The first six leading modes of dynamically induced components explain up to 67.5% of the total variance. The anomalies of evaporation in the North Pacific and the Indian Ocean at low latitudes are mainly related to SST and circulation anomalies induced by SST. The evaporation anomalies in the South Pacific, the North Pacific over middle latitudes and the North Atlantic are directly related to anomalies of circulation. ENSO, and PDO have greater impacts on global ocean evaporation than the NAO. Single factor correlation shows that the Southern Oscillation Index (SOI) and changes in the NAO and PDO coincide with the interdecadal variation of ocean evaporation. In general, the dynamically induced component dominates the interdecadal changes of ocean evaporation mainly by ENSO, NAO, and PDO.