Influence of the El Niño Southern Oscillation to the interannual sea-level variability in the Philippine Sea

Sea level in the Philippine Sea is influenced by climate and oceanographic variables such as the El Niño Southern Oscillation (ENSO), North Equatorial Current bifurcation latitude (NBL), and sea surface temperature (SST). Tide gauges in the eastern Philippines, namely, San Vicente, Baler, Jose Panganiban, Guiuan, and Tandag were established in 2008, while the Legaspi station was established in 1948. We aimed to evaluate the performance of the gridded sea-level anomaly from the Making Earth Science Data Records for Use in Research Environments (MEaSUREs) Project and examined the driving factors for the interannual sea-level variability in the Philippine Sea. The tide gauge and MEaSUREs generally show high correlation (>0.70) and an average root mean square error of 8.6 cm. The tide gauges established after 2008 recorded a relative sea-level fall ranging from −0.92 ± 0.76 to −9.54 ± 0.75 mm/year, while MEaSUREs show an overall rise ranging from 2.80 ± 0.49 to 9.51 ± 0.56 mm/year since 1992. This discrepancy is attributed to the temporary sea-level fall caused by the strong El Niño in 2009/2010 and 2015/2016. The interannual sea-level variability in the Philippine Sea is mainly driven by ENSO. It takes three months for sea level to respond to temperature anomalies in the Niño 3.4 region. Temperature increase (decrease) in the Niño 3.4 region results in the northward (southward) shift of the NBL after two months. The northward (southward) shift in NBL then results in decrease (increase) in sea level after a month, and sea level also increases or decreases in phase with SST.