Integração de Modelagem Numérica (SWAN) e dados de campo na determinação do clima de ondas no litoral setentrional do Rio Grande do Norte

Abstract

This article presents results from the application of the numeric model Simulating WAves Nearshore (SWAN) with comparative analysis among measures from modeling and measurements obtained at a fi eld campaign, done between 2010 and 2012, at the northern coast of Rio Grande do Norte (Northeast of Brazil). The main purpose of the study was to apply and validate the numeric model (SWAN) in wave climate determination, evaluate strong and weak points at the limits for the region of interest. The fi eld data were obtain in two points close to the coast, at 3 m (PT_1) and 6 m (PT_2) under water with two adcp: AWAC and AQUADOPP. The acquired data with these two equipment were process and enable the realization of signifi cant high spectral analysis, HS (m), average period, Tmed (s), and average direction, DIR (º). For the SWAN model implementation, the stirring data from third generation model of the ocean scale Wavewatch III were apply as boundary conditions. Wind and local tide data, after been corrected with the Coastal Engineering Manual (CEM), were introduced resulting in better modeling results adjustment and also model refi nement and applicability. The calculus dominance was referred to nautical chart 720, with three regular mesh with diff erent dimensions and resolution: extern, intermediary and intern, the last one used to give wave propagation parameters through the coast. The confi guration used to SWAN were the steady mode standards, with KOMEN formulations, dissipation from the seabed induced fl ushing from seabed friction using the JONSWAP formulation, with a friction coeffi cient C = 0.015m2s -3 in wind sea conditions and whitecapping or excess slope formulation, triad waves interactions and quadruple wave-wave interactions. The described statistics were analyzed by all data groups, absolute percent error, average squared error, concordance indication, along with the dispersion of the measured and numerical values data as a form of precision and evaluation. Finally, the SWAN model could reproduce and determinate the northern coast wave climate from RN, the results presented a similar trend with the in situ time variation signifi cant high measures (HS, m), however, statistics parametric results were under the waves average period estimative (Tmed, s) in almost every analyzed period, comparing the data from measured points PT_1 and PT_2, and the wave signifi cant high alternation were overestimated with the occasional superposition of peeks episodes