Coco, GiovanniMussi de Albuquerque, Joao2021-03-092021-03-092020https://hdl.handle.net/2292/54610Wave climate statistics are fundamental for navigation, designing near/offshore structures and assessment of coastal hazards. Together with satellite altimeters and buoys, wave hindcasts are the typical source of wave climate data due to their temporal and spatial availability. However, most hindcasts provide wave data as an unimodal set of integrated parameters, even when the sea state is composed of two or more wave systems – which is often the case in New Zealand waters. Furthermore, in the context of climate change, statistics based on current wave data might not represent the future wave climate. This PhD project consisted of generating and studying state-of-the-art multimodal wave climate databases of New Zealand. In order to achieve this, we also developed novel techniques of multimodal wave height correction and wave climate analysis among others. The calibration technique here developed outperformed the standard methods of wave height correction and provided insightful information on the systematic errors present in the wave simulations around New Zealand. This technique is of great use for the wave modelling community as it allows wave height correction along areas where buoy measurements are unavailable. The databases produced are a wave hindcast and past/projected wave data from global circulation models (GCM) ensembles. The hindcast consists of downscaled partitioned WAVEWATCH-III results from a 20-year (1993–2012) global wave model. The boundary forcings extracted from the global simulation were calibrated using the aforementioned wave height correction method. The multimodal wave spectra of each boundary were reconstructed from the partitions and used as wave forcings of a SWAN grid encompassing New Zealand. Waves were downscaled in non-stationary mode and had both partitioned and integrated parameters stored. The partitioned hindcast of New Zealand allowed for the development of a wave climate analysis framework that exploits and displays characteristics of wind-sea and swell waves unseen in previous studies. Such insightful information provided a better understanding of the wave climate of this complex area, and also allowed to identify how atmospheric anomalies modulate the wind-sea and swell waves around New Zealand. The GCM simulated wave climate consists of one 13-year (1993–2006) and two 20-year (2026–2047, 2080–2101) downscales of past and projected wave climate from three GCMs under two representative concentration pathways (RCP4.5, RCP8.5). The boundaries of each downscale grid were also reconstructed from bimodal wave data, which required the development of a data-driven technique based on the “k-nearest neighbour” algorithm to generate directional spread data. The assessment of the anomalies between the past and future simulations of GCMs ensembles produced thoughtful information about the potential changes in the future wave climate, its main drivers and how it may affect New Zealand’s coasts. Such projection databases, together with the hindcast, are crucial for coastal management, risk assessments and climate-change adaptation.Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated.Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated.https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htmhttps://creativecommons.org/licenses/by-nc-sa/3.0/nz/Thesis2021-03-01Copyright: The authorhttp://purl.org/eprint/accessRights/OpenAccessQ112953182