Climate drivers of directional wave power on the Mexican coast

Abstract

Ocean waves are the main driver of sediment transport on open sandy coastlines, and inter-annual to multi-decadal variability in the wave climate significantly impacts year-on-year coastal risk. As such, the integration of large-scale climatic variability into local-scale coastal management studies is pertinent but seldom implemented in practice, mainly due to the lack of knowledge in this subject as is the case of Mexico. This knowledge gap is addressed here by quantifying the seasonal to long-term variability of the wave climate along the coasts of Mexico. The influence of large-scale climate drivers on this variability is also characterized. To do this, we identify monthly-averaged directional wave power signatures of the Mexican coast at a 0.5° resolution pertaining to a range of climate indices, using a newly available climate reanalysis product (ERA5) and a statistical-based global wave climate classification method. The wave climate of the Mexican Pacific coast is strongly bi-directional with considerable seasonal variability and high sensitivity to pan-hemispheric climate variability in the Pacific. Conversely, the wave climate of the Mexican Caribbean coast is more homogenous year-round, having its origins in the tropical Atlantic. Results show that El Nino effects break down the bi-directionality of the Mexican Pacific wave climate, leading to a more uni-directional, shore-normal, and more energetic nearshore wave power climate, compared with ENSO-neutral periods. Additionally, the wave power response to individual ENSO events can be either amplified or dampened depending on the underlying phase of the multi-decadal PDO.