Coastal Upwelling During Normal and EL Nino Years: Case Study of Peru and Oman Upwelling

In this paper the strength and intensity of Peru and Oman upwelling during normal and EL Nino years has been investigated from remote sensing data. Climatological datasets were developed for wind stress, offshore Ekman transport, chlorophyll concentration, Sea surface temperature (SST) and Sea surface heights (SSH) from 20-year data (1998-2017) and normalized anomalies calculated. Regression analysis was performed between El Nino index namely Multivariate ENSO index (MEI) and the normalized anomalies of sea surface parameters. For the Peruvian upwelling, wind stress, Ekman transport, SST and SSH were found to be positively correlated with MEI, while chlorophyll was found to be inversely correlated. It is observed that upwelling favourable trade winds near Peru coastal regions are stronger during El Nino yet biological productivity is lower. SSH, thermocline and mixed layer depth data analysed for the period shows increased stratification and deepening thermocline during El Nino periods. For the Oman coastal waters, it was observed that MEI had an inverse correlation with wind stress anomaly (R
²
=0.49), Ekman transport anomaly (R
²
=0.45) and chlorophyll anomaly (R
²
=0.27). No thermocline deepening was observed near Oman coastal waters during El Nino years.