Interpretation of El Niño–Southern Oscillation‐related precipitation anomalies in north‐western Borneo using isotopic tracers

A strong link between El Niño–Southern Oscillation (ENSO) and precipitation anomalies in north-western Borneo, including Gunung Mulu National Park, has been identified using oxygen isotopic tracers. The study reveals that ENSO modulates the frequency of synoptic-scale wet conditions—such as those driven by the boreal summer intraseasonal oscillation (BSISO), Madden–Julian oscillation (MJO), and Borneo vortex (BV)—which in turn influence rainfall patterns over the region. By analyzing a 7-year isotopic dataset from two sites, researchers found significant correlations between seasonal isotopic anomalies and the Southern Oscillation index, as well as between isotopic signals and area-averaged rainfall anomalies (R = −0.65, p < 0.01). This suggests that ENSO-driven changes in atmospheric circulation patterns directly affect precipitation dynamics in Sarawak.

Kurita, N., Horikawa, M., Kanamori, H., Fujinami, H., Kumagai, T., Kume, T., & Yasunari, T. (2018). Interpretation of El Niño–Southern Oscillation‐related precipitation anomalies in north‐western Borneo using isotopic tracers. Hydrological Processes, 32(14), 2176–2186. Portico. https://doi.org/10.1002/hyp.13164