Marine heatwaves (MHWs) are persistent warming events in the ocean that lasts at least five days to several months. These sea surface temperature anomalies are calculated as exceedance from the 90th percentile based on a 30-year climatological baseline. In the North Sea, the frequency and intensity of MHWs have shown a clear increasing trend over the past 43 years. As illustrated in the animation below, MHW occupancy—defined as the proportion of pixels experiencing MHW conditions—has become significantly more widespread and intense in 2024 compared to 1982.

Abstract: The study was motivated primarily by drowning incidents, which could not be explained because of the lack of physical knowledge of the area. The same problem was deemed consequential to fisheries, navigation, tourism, and other activities in the coastal community. Water trajectories and vectors were obtained from improvised methods and used to explain the water dynamics off the coast of Miagao, Iloilo, Philippines. Direct Lagrangian and Eulerian methods were employed to simulate the two- and three-dimensional water circulations of the study area supplemented by measurements of the wind, tides, and other field variables. The prevalent northeast monsoon (68º) was found as the primary driver of the surface currents (0.33 ± 0.19 ms-1), mainly flowed southwest (208º). A surge in surface flows of up to 200% was observed during the ebb and low tide when the winds and tides were in consonance. These flows turned more laminar in character as evidenced by the robust clustering of the drifters. On the other hand, the subsurface (6 m) currents had a marked clockwise rotation mainly in response to the tides. The tidal current was slower than surface speeds by about 62%. The bathymetric survey revealed that the bottom topography had no significant modifications to the general current patterns. However, the survey revealed deep zones that are potentially hazardous for swimmers, and thus may serve purpose in coastal regulations. The distributions of physico-chemical variables largely reflected the dynamics of the coastal flow and the influence of a river. The findings are deemed valuable to the community and the local government in terms of coastal management.

Three-dimensional circulation off Miagao coast during the northeast monsoon.