Variability of Ocean Heat Content and Marine Heatwaves in the Nordic Seas - presentation

Variability of Ocean Heat Content and Marine Heat Waves in the Nordic Seas Sourav Chatterjee National Centre for Polar and Ocean Research, Goa, India Indian Institute of Tropical Meteorology, Pune, India National Conference on Polar Sciences (NCPS)- 2025 18th September, 2025, Goa, India Source: CMEMS Indian Participants NCPOR, Goa NERCI, Kochi Sourav Chatterjee (PI) Ajith Joseph (PI) Babula Jena (Co-PI) Bindu G (Co-PI) Sathish K (JRF) Saradhy S (JRF) Arctic Ocean Amplification Shu et al., 2022, Sci. Adv. Under the SSP585 scenario, the upper-2000 m of the Arctic Ocean warms at 2.3 times the global mean rate Ocean Heat Transport > Atmospheric Heat Loss Shu et al., 2022, Sci. Adv. Heat Content in the Nordic Seas Source: CMEMS Chatterjee et al., 2018, GRL Largest OHC increase within the deep basin gyres in the Nordic Seas Nordic Seas circulation is not only a passive conduit of Atlantic Water Greenland Sea Gyre circulations redistribute the AW heat within the Nordic Seas and downstream into the Arctic Ocean Chatterjee et al., 2021, The Cryosphere Heat Content in the Nordic Seas Chatterjee et al., 2018, GRL Largest OHC increase within the deep basin gyres in the Nordic Seas Major components of The Lofoten Basin: A. The Front current to the west B. The Slope current to the east C. The deep basin gyre circulation Heat Content in the Nordic Seas Chatterjee et al., 2018, GRL Largest OHC increase within the deep basin gyres in the Nordic Seas Chatterjee et al., 2024, J.Clim Major components of The Lofoten Basin: A. The Front current to the west B. The Slope current to the east C. The deep basin gyre circulation Cold and Fresh anomaly in the Atlantic Water in recent years. Heat Content in the Nordic Seas Yet, Lofoten Basin continued to warm!! – Driven by local processes. Upper Ocean heat content and Steric SSH show increasing trend in the Lofoten Basin (LB), particularly in the southwestern part. One known reason is reduced heat loss in winter (Mork & Skagseth, 2019). Given the importance of LB as the largest AW heat storage and circulation variability, It is imperative to understand the role of The ocean dynamics in the observed trend in OHC. Heat Content in the Nordic Seas Heat Storage Rate (700m) Atmospheric Heat Flux RES -> Oceanic Contribution (advection, diffusion, entrainment etc.) Moisan & Niller, 1998 Heat Content in the Nordic Seas Yet, Lofoten Basin continued to warm!! – Driven by local processes. Recent warming in the Lofoten Basin of the Nordic Seas, despite cooler AW intrusion, is partly driven by a Weakening trend in the Lofoten Gyre circulation, particularly during summer. With heat gain from the atmospheric heat fluxes, changes in the Lofoten Gyre circulation can favour MHW events with subsurface extension (e.g 2003) - comparable atmospheric and oceanic contribution However, with weak contribution from atmospheric fluxes, weakening of the gyre circulation alone can promote subsurface MHW events in the Lofoten Basin, even with weaker surface signal (e.g 2016) –dominated by oceanic contribution. Summary Thank you... [email protected]