Since 1974, there has been a significant increasing trend in land and sea surface temperatures of 0.5 and 0.24°C decade–1, respectively, in the NW Iberian Peninsula. Over the same period, annual precipitation does not show any trend, although some tendencies have been detected at seasonal scales. A significant positive trend, on average of 2 cm decade–1, was also observed in sea level rise from 1943 onwards. Ekman transport perpendicular to the coast (upwelling index) showed a decrease from 1975 to 2008 at both annual and seasonal scales. In addition, the flow of the Miño River (the main river in the area) has also decreased at a mean rate of 18 m3 s–1 decade–1 since 1970. At a synoptic scale, winter cyclone frequency and winter and spring blocking activity have decreased since the 1950s, which may partially explain the winter precipitation decline and the winter and spring temperature increases. These changes in synoptic systems are also in agreement with reported trends in the dominant variability modes of atmospheric circulation affecting NW Iberia, particularly a pronounced positive trend in the North Atlantic Oscillation from the 1970s to the 1990s.

A 3D hydrodynamical model is applied to the ria of A Coruna to analyze the evolution of the circulation pattern in the ria after the building of a breakwater (Barrie de la Maza dock) in the sixties. This circulation pattern has changed greatly. On the one hand, the circulation, which was almost parallel to the shore line under the original conditions, now shows a gyre near the end of the dock. On the other hand, a considerable increase (about 30%) in the velocities near the end of the breakwater and in the main channel of the estuary has been observed after the building of the dock. A stronger bottom shear stress has been generated in the estuary areas where the velocity increased. The bottom shear stress increase was particularly great (over 100%) near the end of the dock. This increase in the shear stress produced bottom erosion and matter resuspension, and consequently major changes in the bathymetry. In addition, in situ sedimentary measurements carried out by Lopez-Jamar (1996) corroborate the bottom erosion in the main chanel of the estuary and at the end of the dock produced by the velocity increase generated by the building of the breakwater.

The performance of the Weather Research and Forecast (WRF) mesoscale model in the ocean surface wind simulation was assessed and evaluated under different initial and boundary forcing conditions. Due to the continuous evolution and progress in the development of reanalyses datasets, this work aims to compare different WRF forcings through reanalyses datasets that are currently kept up to date in near real-time. These datasets consists of the first generation reanalysis NCEP-R2 and two recently released reanalysis datasets that represent the new generation of this type of data (ERA-Interim and NCEP-CFSR). These three reanalyses datasets were used as initial and boundary conditions for the WRF model to simulate surface oceanic wind simulations offshore of the Iberian Peninsula region (more specifically, on the Galician coast and the Gulf of Cádiz). The results are compared with observed wind data from five buoys that measure the wind in the selected region, with the objective of determining which of the three reanalyses produces more accurate wind simulations. The results show that simulations driven with ERA-Interim reanalysis present lower errors when compared to measured winds. This approach provides the most realistic initial and boundary data that can generate ocean wind simulations closest to real winds, although the NCEP-CFSR simulation results are very similar to those obtained with ERA-Interim. The NCEP-R2 reanalysis showed higher errors when compared to the new generation reanalyses. Based on the analysis and results presented in this work, it can be concluded that, for the area under study, the new generation reanalyses are considerably better for ocean wind simulations than the older reanalyses. This is in agreement with the improvement of the models, measurements and data assimilation that are used in the building of the reanalysis datasets. The higher spatial resolutions, the larger amount of assimilated measured data and the improvements of the data assimilation and correction techniques of ERA-Interim and NCEP-CFSR reanalyses data allow for a more accurate and realistic representation of the local wind climate.

This work aims to assess the Weather and Research Forecasting (WRF) model wind simulation and wind energy production estimates sensitivity to different planetary boundary layer parameterization schemes. Five WRF simulations considering different sets of planetary boundary layer (PBL) and surface layer (SL) parameterization schemes were performed, and their results compared to measured wind data collected at five offshore buoys and thirteen onshore wind measuring stations located in the Iberian Peninsula. The objective is to determine which of these model configurations produces wind simulations and wind energy productions estimates closest to measured wind data and wind energy production estimates derived from measurements, aiming to provide guidelines for onshore and offshore wind energy assessment studies focused on areas where measured wind data is not available and numerical modelling is necessary. This work focuses on the Iberian Peninsula, an area with intensive wind energy penetration due to its favourable wind conditions, which combined with its large coastline makes this area a promising one for the future installation of offshore wind farms.The results presented in this work show that, although no major differences are seen among the simulations in terms of wind speed and direction simulation accuracy, in terms of wind energy production estimates the differences are not negligible due to the high sensitivity of the wind energy production to the wind simulation accuracy. The PBL-SL parameterization set composed by the schemes ACM2-PX is the one with the lowest errors when compared to observed wind data, when considering all onshore and offshore sites together. The ACM2 PBL scheme combines features of local and non-local closure schemes and the PX LSM scheme provides a better parameterization of the surface meteorology, which proved to be important in the model performance. However, for offshore sites the PBL-SL parameterizations QNSE-QNSE produced the best wind energy production estimates.Due to the close dependence of each PBL and SL scheme performance on the surrounding synoptic conditions and atmospheric stability, it is expected that for different geographical areas and/or temporal periods these schemes may show different results. However, the fact that this study includes one complete year of simulation for a considerably wide geographical area, including the different synoptic conditions that typically occur in a annual cycle, provides a solid base of confidence that the conclusions drawn from this work may be applied to other periods and/or geographical areas.

Due to the increasing interest in the prospection of potential sites for the installation of offshore wind farms, it becomes important to extend the tests presented on Carvalho et al. (2014) to offshore areas. For that, the WRF model was used to conduct ocean surface wind simulations forced by different initial and boundary conditions (NCEP-R2, ERA-Interim, NCEP-CFSR, NASA-MERRA, NCEP-FNL and NCEP-GFS) aiming to assess which one of these datasets provides the most accurate ocean surface wind simulation and offshore wind energy estimates. Six near surface wind simulations were performed, each one of them forced by a different initial and boundary dataset. Results were evaluated using data collected at five buoys that measure the wind in the Iberian Peninsula region (Galician coast and Gulf of Cádiz).The results show that the simulation driven with ERA-Interim reanalysis provided the lowest errors in terms of offshore wind temporal variability. NCEP-R2 driven simulation showed the lowest offshore wind speed bias, mean wind speed and offshore wind energy production estimates. However, it was the one with the highest errors related to the wind temporal variability. The simulations driven with the NCEP-FNL and NCEP-GFS analyses products also showed interesting results, better than the NCEP-CFSR and NASA-MERRA reanalyses.Based on the results presented in this work and in Carvalho et al. (2014), ERA-Interim reanalysis likely provide the most accurate initial and boundary data to force near-surface wind simulations for the offshore and onshore areas. However, for offshore sites the NCEP-R2 reanalysis seem to provide the most accurate estimation of the potential wind energy production, fact that is of great importance for the wind energy industry. Furthermore, the NCEP-GFS and NCEP-FNL analyses can be considered as valid alternatives to ERA-Interim and NCEP-R2, in particular for cases where reliable forcing data is needed for real-time applications due to their fast availability.

Offshore wind data derived from satellite measurements (CCMP, QuikSCAT, NCDC Blended Sea Winds and IFREMER Blended Wind Fields), reanalyses (NCEP-CFSR, ERA-Interim, NASA-MERRA and NCEP-RII), analyses (NCEP-FNL and NCEP-GFS) and WRF modelled offshore winds were compared to in situ measurements, in order to assess which one of these products is the best alternative to in situ offshore measured wind data. Wind speed and direction from these products were compared to measurements collected at five buoys moored along the Iberian Peninsula Atlantic coast.Results show that WRF modelled offshore winds are the best alternative to in situ measured offshore wind data, showing the highest temporal accuracy (the ability in representing the wind speed and direction at a given time instant) and lowest errors in terms of offshore wind power flux estimations. However, offshore wind data taken from CCMP shows the lowest errors in terms of the mean wind speeds and, together with IFREMER-BWF, the best wind temporal accuracy after WRF simulation. Therefore, in general CCMP and IFREMER-BWF can be considered as the best alternatives to WRF high resolution modelled offshore winds, if the latter is not available. Specifically for offshore wind energy resource assessment, NCEP-CFSR reanalysis or NCEP-GFS analysis data can also be used with confidence as an alternative to WRF modelled data, showing better wind power flux estimates than CCMP and IFREMER-BWF.Despite the best performances of WRF high resolution offshore winds, such modelling tasks require considerable computational resources and time to obtain quality results. Therefore, the value of satellite-derived wind data should not be disregarded. These remotely sensed offshore wind measurements should be seriously considered when searching for alternative sources of wind information for ocean areas, in particular for open ocean areas where they have their strength. © 2014 Elsevier Inc.

The performance of the WRF mesoscale model in the wind simulation and wind energy estimates was assessed and evaluated under different initial and boundary forcing conditions. Due to the continuous evolution and progress in the development of reanalyses datasets, this work aims to compare an older, yet widely used, reanalysis (the NCEP-R2) with three recently released reanalyses datasets that represent the new generation of this type of data (ERA-Interim, NASA-MERRA and NCEP-CFSR). Due to its intensive use in wind energy assessment studies, the NCEP-GFS and NCEP-FNL analysis were also used to drive WRF and its results compared to those of the simulations driven by reanalyses.Six different WRF simulations were conducted and their results compared to measured wind data collected at thirteen wind measuring stations located in Portugal in areas of high wind energy potential. Based on the analysis and results presented in this work, it can be concluded that the new generation reanalyses are able to provide a considerable improvement in wind simulation when compared to the older reanalyses. Among all the initial and boundary conditions datasets tested here, ERA-Interim reanalysis is the one that likely provides the most realistic initial and boundary data, providing the best estimates of the local wind regimes and potential wind energy production. The NCEP-GFS and NCEP-FNL analyses seem to be the best alternatives to ERA-Interim, showing better results than all the other reanalyses datasets here tested, and can therefore be considered as valid alternatives to ERA-Interim, in particular for cases where reliable forcing data is needed for real-time applications due to its fast availability.

Sea surface temperature (SST) variability was analyzed for the Bay of Biscay over the period 1982–2014 using data from NOAA 1/4 degree daily OI database. Trends were analyzed on a monthly scale since previous studies suggest that the rate of change was not homogeneous at annual and seasonal scales. The warming calculated for the whole area at the annual scale was 0.26 ± 0.03°C dec−1, although the intensity was observed to depend on themonth. Higher warming trends were detected from September to November and from April to June with values higher than 0.3°C dec−1, whilst lower SST trends were detected from January to March and from July to August with values below0.2°C dec−1.Warming ismainly due to the increase in the duration of thewarmseason (between 6 and 14 days dec−1)more than the milder winters or warmer summers. This fact ismainly responsible for the increase in the frequency of extreme hot SST days measured in spring (1.16 ± 0.23 days dec−1) and autumn (1.81±0.42 days dec−1). In contrast, trends observed during the warmestmonth (August), are characterized by an increase (~1.0 days dec−1) near shore and a decrease (~−1.0 days dec−1) in the oceanic part of the bay.

Coastal and oceanic sea surface temperature (SST) trends were analyzed in the Benguela upwelling ecosystem from the seventies on. Monthly SST data were obtained from the UK Meteorological Office, Hadley Center at two transects in front of the Namibia coast and the western coast of South Africa. A positive SST trend (0.06 °C dec−1) is observed at open sea locations and a negative one (−0.13 °C dec−1) near shore. The observed negative ΔSST (SSTcoast−SSTocean) trend (−0.18 °C dec−1) is linked to the strengthening of upwelling (87 m3 s−1 km−1 dec−1) during the same period. For this purpose, Ekman transport was directly obtained from the Pacific Fisheries Environmental Laboratory in the area under study and calculated from reanalysis wind data from NCEP/NCAR at six locations in front of the Namibia coast and the western coast of South Africa. This coastal upwelling enhancement is in good agreement with changes in the intensity and location of the South Atlantic High, which are also reflected in the Southern Annular Mode (SAM) index.

The coastal area north of Yucatan has experienced a cooling SST trend from 1982 to 2015 during the upwelling season (May–September) that contrasts with the warming observed at the adjacent ocean area. Different drivers were analyzed to identify the possible causes of that unusual coastal cooling. Changes in coastal upwelling and in sea-atmosphere heat fluxes are not consistent with the observed coastal cooling. The eastward shift of the Yucatan Current observed over the last decades is hypothesized as the most probable cause of coastal cooling. This shift enhances the vertical transport of cold deeper water to the continental shelf from where it is pumped to the surface by upwelling favorable westerly winds.