Climatology of wind patterns in the northeast of the Iberian Peninsula

A classification of daily surface wind fields over the Comunidad Foral de Navarra (CFN) region (northeastern Iberian Peninsula (IP)) into wind pattern (WP) types is performed. Daily wind data measured at 41 meteorological stations are employed to represent the surface wind field. Two methodologies are used to develop the classification, one based oil the spatial and the other oil the temporal similarity. Both methodologies produce comparable results yielding six robust wind patterns. The detected wind field types are season dependent, thereby revealing an annual Cycle evolution. The patterns with northwestern Circulations are dominant (60.9%) followed by the southeastern ones (30.5%), showing the strong influence of the orography over surface circulations, since valleys in the region are directed mainly along the NW-SE direction. A sea level pressure (SLP) map pattern classification is also performed to evaluate the connections between the synoptic circulations and the surface flows. Eight pressure patterns (PPs) were identified and related to the surface WPs already formed. The associations found were clear enough to understand the forcing mechanism of the different WPs. The ageostrophic balance and the pressure gradient along the valleys seem to successfully describe the general characteristics of the surface circulations over the study region. The behaviour of some atmospheric parameters such as temperature, relative humidity, global radiation and precipitation, which help to describe the atmospheric state associated with each surface circulation type, is also described. They show different advective regimes, and in particular the cold and dry northwestern strong wind locally known as Cierzo and the warm and moist southeastern wind known as Bochorno are recognized. A WP responsible for precipitation episodes of high intensity in the northern region of the CFN is also recognized. Copyright (C) 2008 Royal Meteorological Society