El Nino has changing wind patterns. Wind pushes the ocean water around:<p>It leads to the Eastern Pacific (America) being lower than the West (Asia) normally (surface wind goes west), normally about ~50cm above mean before Asia and about 20cm below mean before America.<p>This changes during El Nino events, when the surface wind changes direction and the water is pushed the other way (~20cm below mean before Asia and 20cm above mean before America). Those values include thermal expansion and stuff.<p>The Marshall islands are more to the Asia side of the Pacific. There is  a ~20cm dip in 1998. [1] It fits.<p>[1] <a href="http:&#x2F;&#x2F;sealevel.colorado.edu&#x2F;content&#x2F;interactive-sea-level-time-series-wizard?dlat=7&amp;dlon=171&amp;fit=n&amp;smooth=g&amp;days=100" rel="nofollow">http:&#x2F;&#x2F;sealevel.colorado.edu&#x2F;content&#x2F;interactive-sea-level-t...</a>