Wind forcing of the coastal circulation off north and northwest Iberia: Comparison of atmospheric models

Abstract

Comparisons between observed winds and winds from reanalysis (National Centers for Environmental Prediction (NCEP) Reanalysis 1 and 2) and forecast meteorological models (High‐Resolution Limited Area Model (HIRLAM)‐Agencia Estatal de Meteorologia 0.2° and Atmospheric Research Mesoscale Model version 5‐MeteoGalicia with 30 km and 10 km resolution) have been performed for the coastal region around northwest and north Iberia during a typical autumn downwelling period (September–December 2002). Observations at buoys and coastal stations and QuikSCAT‐derived winds were employed. The analyzed period was dominated by southerly and southwesterly winds associated to the passage of low‐pressure systems. Our results show that the westward component is higher on the north coast than on the west coast and that winds are intensified at the western north coast. In this situation, the performance is similar in all model products in general terms, but only HIRLAM represents the reduction of winds in the Cantabrian Sea and NCEP and MM5 overestimate the magnitude of south‐southwest winds. Spatial differences in winds are also obtained for upwelling favorable events, associated either with a high‐pressure system north from Iberia at the beginning of the autumn transition (northeasterly winds) or with conditions after the passage of a low‐pressure system (northwesterly winds). The existence of sea surface temperature (SST) gradients in the coastal region implies that higher‐resolution boundary SST products for meteorological models are necessary. Finally, the effect of these wind products on the coastal circulation was assessed with a 3‐D numerical simulation. Differences in the expansion/confinement of river plumes and the surface speed of the slope current are induced by differences in wind patterns over the shelf and slope area among atmospheric models.