Wind variability in a coastal area (Alfacs Bay, Ebro River delta)

Abstract

Abstract. Wind spatial heterogeneity in a coastal area (Alfacs Bay, northwestern Mediterranean Sea) is described using a set of observations and modelling results. Observations in three meteorological stations (during 2012-2013) along the coastline reveal that wind from the N-NW (strongest winds in the region) appears to be affected by the local orography promoting high wind variability on relatively short spatial scales (of the order of few kilometres). On the other hand, sea breezes in late spring and summer also show noticeable differences in both spatial distribution and duration. The importance of wind models' spatial resolution is also assessed, revealing that high resolution ( = 3 km) substantially improves the results in comparison to coarse resolution (9 km). The highest-resolution model tested (400 m) also presents noticeable improvements during some events, showing spatial variability not revealed by coarser models. All these models are used to describe and understand the spatial variability of the typical wind events in the region. The results presented in this contribution should be considered on hydrodynamic, ecological and risk management investigations in coastal areas with complex orography.

Ocean–atmosphere–wave characterisation of a wind jet (Ebro shelf, NW Mediterranean Sea)

“…A channelisation effect associated with the Ebro valley triggers north-westerly winds (called Mestral: Catalan for Mistral wind), resulting in a wind jet. Previous studies based on long-term wind measurements in the proximity of the region showed that winds have a persistent seasonal pattern (Font, 1990;Cerralbo et al, 2015;Grifoll et al, 2015). During winter and autumn, a dominant northwesterly component caused by wind channelisation was observed.…”

“…The westerly wind, greatly affected by the orography, is channelised into a limited band, forming a wind jet (Jansà, 1985;Spanish Ministry of Energy, 2014). The synoptic situation is related to an anticyclone in the Bay of Biscay and a low-pressure area in the Mediterranean Sea (Riosalido et al, 1986;Font, 1990;Martín-Vide, and Olcina, 2001;Cerralbo et al, 2015). Offshore wind is more usual and intense during autumn and winter, when larger atmospheric pressure gradients take place and cause stronger winds with an advection of cold air, but a small atmospheric pressure difference along the Ebro valley is sufficient to initiate wind during any season (Riosalido et al, 1986;Cerralbo et al, 2015).…”

Hydrodynamic response in a microtidal and shallow bay under energetic wind and seiche episodes

“…It is evident that other processes entirely mask the linear response, assuming a linear behavior as an expected direct response of the water current at wind forcing. It means that the hydrodynamic response is conditioned by nonlinear and non-stationary processes due to the intricate bathymetry, the unsteadiness of the wind magnitude and direction and probably the spatial wind heterogeneity in the bay (Cerralbo et al, 2015). Aside Alfacs Bay, this behavior is common in highly-stratified and shallow estuaries where the correlation with wind events is complex and nonlinear (Noble et al 1996, Narváez and.…”

Modeling circulation patterns induced by spatial cross-shore wind variability in a small-size coastal embayment

“…The three-dimensional hydrodynamic model used in this study is the Regional Ocean Modeling The skill assessment of the atmospheric model was presented previously in Cerralbo et al (2015b).…”