Title: Indian Ocean Dipole-Induced Decoupling of Sea Surface pCO2 and Temperature in the Northern Bay of Bengal

Time: May 24th (Sunday), 1:30pm-3:00pm

Location: 13rd floor meeting room, Haozhiying Technology Tower

Abstract:The partial pressure of carbon dioxide at the sea surface (pCO₂sea) is an important part of the ocean carbon cycle and is controlled by temperature, ocean circulation, and biological processes. Normally, sea surface temperature (SST) and pCO₂sea increase or decrease together because warmer water releases more carbon dioxide. However, this study shows that during Indian Ocean Dipole (IOD) events, this normal relationship breaks down in the northern Bay of Bengal. Using observations, reanalysis data, and BIO-ROMS model simulations, the study found that non-temperature processes play a major role in controlling pCO₂sea during these periods. During positive IOD events, dissolved inorganic carbon (DIC) and sea surface salinity (SSS) increase and strongly raise pCO₂sea, even though cooler sea surface temperatures tend to reduce it. Negative SST anomalies in the eastern equatorial Indian Ocean trigger atmospheric circulation changes known as the Matsuno–Gill response. These changes increase evaporation and reduce rainfall over the northern Bay of Bengal, causing higher salinity and higher DIC levels in surface waters. At the same time, stronger wind-driven ocean circulation and upwelling in the northwestern Bay of Bengal bring cold, carbon-rich subsurface water to the surface. This process cools the surface water but further increases DIC and pCO₂sea. In addition, unusual southerly winds weaken the East India Coastal Current and transport more saline water into the region, which further enhances pCO₂sea. Overall, the study demonstrates that ocean circulation and salinity changes can strongly influence sea surface carbon dioxide levels, sometimes overriding the normal effect of temperature during IOD events in the Bay of Bengal.

bio

Prof. Tilak Priyadarshana is a senior professor in Limnology and Water Technology, Co-director of the China-Sri Lanka Joint Center for Education and Research, Director, Quality Assurance Council of the University Grants Commission, Former Dean, Faculty of Fisheries and Marine Science & Technology. Project Director of the University of Ruhuna Township Development Project, Former President of Sri Lanka University Sports Association, Former Director, International Affairs, University of Ruhuna, Former Director, Internal Quality Assurance Unit, University of Ruhuna

Editor-in-Chief of the UoR Highlights, the official newsletter of the University.

He is also a distinguished academic and researcher in ecological engineering and environmental conservation. He obtained his PhD in Ecological Engineering from Saitama University, Japan, and further pursued a Postgraduate Diploma in International Environmental Law from UNITAR, Switzerland, reflecting his deep commitment to environmental sustainability. He is a recipient of the prestigious Japan Society for the Promotion of Science (JSPS) Fellowship at Saitama University. Recognizing his contributions to international collaboration, he was honored with the Guangdong International Cooperation Award by the Guangdong Government, China, in 2019.

Research & Contributions

Professor Gamage has secured numerous competitive research grants, including a National Research Council (NRC) Grant for his groundbreaking work on the Restoration of the Ancient Ruhunu Rata Tank System as a Climate Adaptation Strategy to Meet Future Water Demand and Livelihood Development. His research has led to innovative technologies in ecological engineering and sustainable water management.

Academic & Administrative Leadership

From 2008 to 2014, he served as the Dean of the Faculty of Fisheries and Marine Sciences & Technology at the University of Ruhuna. From 2015 to 2019, he was the Director of Internal Quality Assurance, where he was instrumental in establishing an academic accountability model and the Quality Assurance Management Information System (QAMIS). He later served as the Director of International Affairs at the university.

Leadership & National Contributions

Professor Gamage has held multiple leadership positions, including:

· President, Sri Lanka University Sports Association (SLUSA)

· Co-Director, China-Sri Lanka Joint Center for Education and Research

· Project Director, University of Ruhuna Township Development Project

· Editor-in-Chief, UoR Highlights (the official university newsletter)

Additionally, he has served as:

· Director, Quality Assurance Council, University Grants Commission (UGC)

· Board Member, National Institute of Fisheries and Nautical Engineering (NIFNE)

· Committee Member, Sri Lanka Association for the Advancement of Science (SLAAS)

· Committee Member, National Development Plan for the Fisheries Sector (2005), focused on tsunami-affected communities

· Member, UGC Standing Committees on Science & Quality Assurance

· Expert Panel Member, Five-Year Development Plan for Agriculture, Fisheries, and Environmental Activities in the Southern Province

Professor Gamage has also served as an environmental expert for over twenty Technical Evaluation Committees appointed by the Central Environmental Authority of Sri Lanka, contributing to various national development projects.

联系人： 张晓琳， zhangxiaolin@dlmu.edu.cn (19104337597)