Reconstructing Tropical Pacific Sea Level Variability for the Period 1961–2002 Using a Linear Multimode Model

2018 - Journal of Geophysical Research: Oceans


Richard J. Greatbatch

Additional authors:

Xiaoting Zhu, Martin Claus


doi: 10.1002/2017JC013652


Monthly mean sea level anomalies in the tropical Pacific for the period 1961–2002 are reconstructed using a linear, multimode model driven by monthly mean wind stress anomalies from the NCEP/NCAR and ERA‐40 reanalysis products. Overall, the sea level anomalies reconstructed by both wind stress products agree well with the available tide gauge data, although with poor performance at Kanton Island in the western‐central equatorial Pacific and reduced amplitude at Christmas Island. The reduced performance is related to model error in locating the pivot point in sea level variability associated with the so‐called “tilt” mode. We present evidence that the pivot point was further west during the period 1993–2014 than during the period 1961–2002 and attribute this to a persistent upward trend in the zonal wind stress variance along the equator west of W throughout the period 1961–2014. Experiments driven by the zonal component of the wind stress alone reproduce much of the trend in sea level found in the experiments driven by both components of the wind stress. The experiments show an upward trend in sea level in the eastern tropical Pacific over the period 1961–2002, but with a much stronger upward trend when using the NCEP/NCAR product. We argue that the latter is related to an overly strong eastward trend in zonal wind stress in the eastern‐central Pacific that is believed to be a spurious feature of the NCEP/NCAR product.