Spatial and temporal variability of the Iberian Peninsula coastal low-level jet

Rijo N, Lima DCA, Semedo A, Miranda PMA, Cardoso RM, Soares PMM
IJC, Volume 38, Issue 4,

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The spatial variability and the climatic characteristics of the coastal low-level jet along the west coast of the Iberian Peninsula are presented in this study, based on a 9-km resolution downscaling data set, produced using the weather research and forecasting model, forced by the ERA-Interim reanalysis. The west coast of Iberia is divided into two (north and south) subareas, where the Iberian Peninsula coastal jet (IPCJ) characteristics are studied separately, and compared to the whole western Iberia. It is shown that while IPCJ occurrences are more frequent in the southern area, during summer (June-August), the jet mean wind speed maxima is highest in the northernmost area. The along- and cross -coast sea surface temperature (SST) structure is studied and linked to the coastal wind speed. It is also shown that the local cross-coast marine atmospheric boundary layer gradient at the coast is considerably higher than the synoptic one, and that this difference is responsible for the local intensification of the wind speed. The flow interaction with the three major capes along the west coast of Iberia (Finisterre, Roca, and Saint Vincent) is responsible for local higher occurrence of the IPCJ, as well as the downwind intensification of the wind speed. The along-coast west Iberia wind speed structure due to IPCJ occurrences is shown. The diurnal cycle of the IPCJ is studied in the extended boreal summer (May-September), with higher mean IPCJ occurrences and jet wind speeds in late the afternoon.