The Upwelling Phenomenon: A Blessing for Indonesian Fishermen

Darilaut – The start of the dry season triggers strong Easterly winds. These winds push surface seawater towards the open sea, which is then replaced by nutrient-rich cold water masses from deeper layers. “The upwelled water mass brings ‘natural fertiliser’ in the form of nitrates and phosphates,” said Widodo S. Pranowo, Senior Expert Researcher in Applied Oceanography and Coastal Management at BRIN’s Climate and Atmosphere Research Centre, on Monday (16/3). “When it reaches the sunlit surface, massive photosynthesis occurs by phytoplankton. This is the basis for the increase in our marine primary productivity,” he stated, citing Brin.go.id. Therefore, the dry season predicted to start earlier in April 2026 is a serious concern for oceanography researchers. Although this phenomenon is often associated with drought on land, for the maritime sector, this seasonal transition becomes a moment of extraordinary marine fertility increase through the upwelling phenomenon. Based on research published by Widodo Pranowo in the Indo-Maritime Magazine 2014, the upwelling phenomenon south of Java has unique characteristics known internationally as RATU (Semi-permanent Java Coastal Upwelling). The research results show that the intensity of RATU is greatly influenced by seasonal dynamics and global climate variability. In that study, the use of Argo Float robotic autonomous diver technology, operating up to a depth of 2,000 metres, was key in recording real-time temperature and salinity profile data.