Sea-surface temperature variability and climate drivers in Cuba's Jardines de la Reina National Park (2003–2022)

Abstract. Coral reef systems on the southeastern Cuban shelf are exposed to rapid warming and increasingly frequent marine heatwaves (MHWs). However, the physical drivers of local sea-surface temperature (SST) variability remain poorly quantified. The present study examines seasonal-to-decadal SST variability in and around the Jardines de la Reina National Park (JRNP) and investigates the extent to which atmospheric–ocean processes and large-scale climate modes influence that variability. The study analyses daily 1-km Multi-Scale Ultra High Resolution (MUR) SST from 2003–2022, in conjunction with ERA5 surface heat fluxes and GLORYS12 mixed-layer fields. A mixed-layer heat budget, compiled from daily values and averaged to monthly values, is used to attribute the seasonal cycle; long-term trends, MHWs and modes of variability (Orthogonal Functions) can be used to explain interannual to decadal changes and their links to El Niño Southern Oscillation (ENSO), the Western Hemisphere Warm Pool (WHWP), the Tropical North Atlantic (TNA) and the North Atlantic Oscillation (NAO).

Net air–sea heat exchange sets the seasonal evolution of SST, whereby horizontal advection provides a smaller modulation near the shelf break; a characteristic ~2-month lead of heat flux over temperature is consistent with mixed-layer heat storage. This thermodynamic control explains a marked autumn–winter shelf–offshore contrast between the shallow gulfs (Gulfs of Ana María and Guacanayabo) and the adjacent Caribbean Sea. Superimposed over this area is a warming trend of ~0.28°C decade⁻¹ (strongest in winter/transition months, peaking around April at ~0.48°C and November at ~0.35°C decade⁻¹) and a step-like shift in 2011–2013 towards a persistently warmer state. MHWs intensified during the second decade; the mean event-wise maximum intensity was higher inside GAM, while upper categories occurred more frequently offshore. EOF1 (87.5 %) is a basin-wide mode linked on an interannual basis to ENSO/WHWP and latent-heat flux and at low frequency to the NAO, while EOF2 (6.2 %) captures a shelf–offshore dipole related to TNA.

The aforementioned results provide a physical basis for which to issue early warnings from forecasts of net heat flux and mixed-layer depth, thus encouraging the use of regional high-resolution modeling and targeted observations. Key limitations to the present study include a 20-year MHW baseline and an under-resolution of currents in highly shallow and complex bathymetry.