The northerly summer wind off the west coast of the iberian peninsula

Abstract

Winds are a natural hazard for mariners and for offshore infrastructures. In spite ofhaving been used as a propulsion system throughout times, nowadays it can be a source of danger in extreme situations. High wind speeds can also represent an economic driver, since, on the one hand, wind energy can be harvested from off-shore wind farms, but on the other hand fishing activity or, for example, off-shore fish farms are affected. The predominant winds in the North Atlantic (the Westerlies) have a basin-wide scale, and are highest during winter. During summer, when the large scale forcing is weaker, mesoscale and local wind features prevail. That is the case of coastaljets. During summer the Iberian Peninsula is under the effect of the semi-permanent Azores High and of a thermal low pressure system in-land. This synoptic pattern drives a seasonal northerly wind along the west coast of the Iberian Peninsula. This regional wind is an example of a coastaljet. An insight on the climatology of the Iberian Peninsula coastal jet (IPCJ) is presented, based on a regional reanalysis produced with the WRF mesoscale model for the period 1989-2007. It is shown that although the IPCJ are more frequent in the south area of the west coast of Iberia, in the north area coastaljets are stronger (with higher wind speeds). The dynamic structure of the IPCJ is studied through the analysis of a strong summer IPCJ event along west coasts of Galicia and north of Portugal (at 3 km horizontal resolution). This case study was identified in vicinity ofAveiro on 14th July 2002 at 1900 local time.