Análisis de episodios de viento en un área costera: una herramienta para la estimación de la variabilidad en la turbulencia en estudios con plancton

[EN] Turbulence at different scales, from generation to dissipation, influences planktonic communities. Many experimental studies have recently been done to determine the effects of small-scale turbulence on plankton, but it is difficult to state the relevance of the findings since there is little unbiased information on turbulence variability in the sea. In this study, we use wind velocity data series from several meteorological stations located along the Catalan coast to estimate the spatial and temporal variability of small-scale turbulence in the upper ocean. Using a peaks-over-threshold approach, we develop a statistical model to assess the frequency of wind events as a function of their persistence and intensity. Finally, the wind speed data series are converted into turbulent energy dissipation rate estimates at 1 m depth to determine the general distribution of turbulence on the Catalan coast. Geographical variability is larger than seasonal variability in frequency and persistence of wind events, owing to differences in local relief. These statistical models developed for wind events combined with empirical relationships between wind and turbulence, are tools for estimating the occurrence and persistence of turbulent events at a given location and season. They serve to put into context the past, present and future studies of the effects of turbulence on coastal planktonic organisms and processes[ES] La turbulencia a diferentes escalas, desde su generación a su disipación, afecta a la comunidad planctónica. Recientemente el interés por los efectos de la turbulencia de escala pequeña se ha desarrollado mucho, pero es difícil establecer la importancia de tales estudios, puesto que no hay información completa de la variabilidad de la turbulencia en el mar. En el presente trabajo, usamos series de datos de viento provenientes de diversas estaciones meteorológicas situadas a lo largo del litoral catalán para estudiar la variabilidad espacio-temporal de la turbulencia de escala pequeña. Mediante una aproximación POT ("peaks-over-threshold"), desarrollamos un modelo estadístico para estimar la frecuencia de episodios de viento, en función de su persistencia e intensidad. Los datos de velocidad de viento son utilizados para estimar las tasas de disipación de la energía turbulenta a 1 metro de profundidad, con el fin de determinar la distribución general de la turbulencia en la costa catalana. Debido al relieve local, la variabilidad geográfica es mayor que la estacional en la frecuencia y persistencia de episodios de viento. El modelo estadístico desarrollado, junto con relaciones empíricas entre viento y turbulencia, pueden ser usados para estimar la ocurrencia y frecuencia de episodios en una localidad y estación dadas. Sirven para poner en contexto estudios pasados, presentes y futuros sobre los efectos de la turbulencia en el planctonO.G. had a Spanish CSIC-I3P fellowship sponsored by INNOVA oceanografía litoral, S.L. This study was supported by the EU project NTAP (EVK3-CT-2000-00022) and Spanish projects TURFI (REN2002-01591/MAR) and VARITEC (REN2003-08071-C02-01/MAR). This is ELOISE contribution 519/40Peer reviewe

Analysis of wind events in a coastal area: a tool for assessing turbulence variability for studies on plankton

Turbulence at different scales, from generation to dissipation, influences planktonic communities. Many experimental Studies have recently been clone to determine the effects of small-scale turbulence on plankton. but it is difficult to state the relevance of the findings since there is little unbiased information on turbulence variability in the sea. In this study, we use wind velocity data series from several meteorological stations located along the Catalan coast to estimate the spatial and temporal variability of small-scale turbulence ill the upper ocean. Using a peaks-over-threshold approach, we develop a statistical model to assess the frequency of wind events as a function of their persistence and intensity. Finally, the wind speed data series are converted into turbulent energy dissipation rate estimates at 1 m depth to determine the general distribution of turbulence oil the Catalan coast. Geographical variability is larger than seasonal variability in frequency and persistence of wind events, owing to differences in local relief. These statistical models developed for wind events combined with empirical relationships between wind and turbulence, are tools for estimating the occurrence and persistence of turbulent events at a given location and season. They serve to Put into context the past, present and future Studies of the effects of turbulence on coastal planktonic organisms and processes