Was It the Pacific Decadal Oscillation That Caused the 1998-2002 Anomaly in Earths Oblateness J2?
In a recent paper published in AGU’s electronic journal G-Cubed, Ben Chao and his “ABC Team” — Andy Au, Jean-Paul Boy, and Chris Cox, analyzed the sea-surface height and sea-surface temperature data for the extratropic Pacific basins in search of the phenomena that have caused the 1998-2002 anomaly in Earth’s oblateness J2 as observed by the satellite laser ranging technique. In the process, they found that, on interannual and longer timescales, the temporal evolution of the J2 has a strong correlation with that of the so called Pacific Decadal Oscillation (PDO). This strongly implies that the water mass transport associated with PDO in the ocean is directly or indirectly causing the interannual J2 variations. The figure below shows the said correlation over the last 20+ years. The red curve is the observed interannual J2 variation; the blue curve is the PDO Index but shifted towards positive time by 5 months (with an empirical scaling for visual comparison).
