Challenges of building an operational ocean forecasting system for small island regions: regional to local

Abstract

An ocean circulation forecasting model for the Madeira Archipelago is operational since May 2010. Developing a forecasting system for a small island oceanic region, deprived from in-situ observations, is a challenging task since there are limited ways to validate predictions. Furthermore, model resolution concurrent with insufficient computational power, locally available, are other limiting factors to consider. Regional models combined with the possibility to downscale solutions onto a higher resolution island-scale model is a way to overcome some of such limitations. Nevertheless, generalised regional models must be able to accurately represent the far-field and transport important features such as meddies onto the local systems; while island-scale models must have sufficient grid resolution as well as adequate physics and accurate atmospheric forcing to resolve the near-field phenomena. An island-induced cyclonic eddy event was successfully observed and forecasted with the current approach (regional-local). Generalised single (regional) model initiatives will prove to be insufficient to deal with mesoscale dynamic systems, islands and seamounts are important generators of mesoscale features in the NE Atlantic, with basin scale implications. The forecasting systems of the future should also consider upscaling valid local (island-scale) solutions onto Regional and/or Global models.

Modeling the air‐sea feedback system of Madeira Island

“…Accurate forecasting of coastal oceanic and atmospheric circulation is particularly challenging in island regions due to a number of factors [ Caldeira et al ., ]. From a geographical perspective, many islands possess steep terrain and heterogeneous microclimates.…”

Coupled ocean-atmosphere forecasting at short and medium time scales

“…Caldeira and Tomé (2013) speculated that lee-side ocean warming results from the enhanced solar heating of cloud-free atmospheric wakes. Caldeira et al (2002) and Caldeira (pers. comm.…”

“…Islands represent a challenging and important setting for coupled modeling systems (Caldeira et al 2016). Ocean features initiated by islands (such as mesoscale eddies, filaments, and warm wakes) generate distinct sea surface temperature (SST) signatures (Sangrà et al 2007).…”

“…Of particular interest in this regard are local impacts generated by submesoscale and mesoscale SST variations that can alter heat fluxes and winds. Warm SSTs are commonly found in the lee of islands (Caldeira et al 2002). Caldeira and Tomé (2013) speculated that lee-side ocean warming results from the enhanced solar heating of cloud-free atmospheric wakes.…”

Skill assessment of global, regional and coastal circulation forecast models: evaluating the benefits of dynamical downscaling in IBI surface waters

“…Despite the recent advances in the development of CMEMS global and regional core products, many downstream services for user uptake require information on even smaller spatial scale, such as ocean forecasting for small island chains (Caldeira et al, 2016), intricate bights (Stanev et al, 2016) or port approach areas where sharp topo-bathymetric gradients pose special difficulties for accurate local predictions (Sotillo et al 2018, under review;Hlevca et al, 2018;Federico et al, 2017;Sánchez-Arcilla et al, 2016;Sammartino et al, 2014;Grifoll et al, 2012). A variety of operational products for harbours have been recently developed, although most of these coastal applications are wave and water-level forecasting systems (Lin et al, 2008;Pérez et al, 2013).…”