Storm-tide and wave interaction at Puerto Rico during Hurricanes Irma and Maria

In this study, the storm-tide and waves associated with Hurricanes Irma and Maria that struck Puerto Rico (PR) successively in 2017 were simulated using a coupled circulation and spectral wave model (TELEMAC2D + TOMAWAC), and validated against water level and wave measurements from gauges deployed around the island. Particular emphasis was placed on the storm-tide and wave interaction in the coastal area of San Juan, the capital of PR. At the San Juan coast, Irma caused a maximum of $\sim$0.2 m surge and 0.2–0.3 m wave setup, while Maria induced a larger maximum surge of nearly 1.0 m but a smaller wave setup at 0.1 - 0.2 m. Meanwhile, Irma-induced waves caused a strong westward longshore current ($\sim$2 m/s), which interacted with the storm-tide associated eastward current ($\sim$0.5 m/s) and led to small-scale gyres (several hundred meters in diameter) and rip currents formed near the coast, that in turn affected the significant wave height (SWH) locally. In contrast, during the passage of Maria, the wave- and storm-tide-induced longshore currents were in the same westward direction (maximum at $\sim$1 m/s and $\sim$3 m/s respectively); the strong current first refracted the waves towards the following current status (wave and current propagating in the same direction) and then decreased the significant wave height by nearly 2 m in a relatively large area ($\sim$2 km wide band along the coastline) off the coastal shelf.