Comparison of reanalyzed, analyzed, satellite-retrieved and NWP modelled winds with buoy data along the Iberian Peninsula coast D. Carvalho a, ⁎, A. Rocha a , M. Gómez-Gesteira b , C. Silva Santos c a CESAM, Department of Physics, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal b EPHYSLAB — Environmental Physics Laboratory, Facultad de Ciencias, Universidad de Vigo, 32004 Ourense, Spain c Instituto Superior de Engenharia do Porto, Rua Dr. António Bernardino de Almeida 341, 4200-072 Porto, Portugal abstract article info Article history: Received 14 April 2014 Received in revised form 26 June 2014 Accepted 19 July 2014 Available online 6 August 2014 Keywords: Cross-Calibrated Multi-Platform Ocean Wind (CCMP) QuikSCAT WRF Wind simulation NCEP-R2 ERA-Interim NCEP-CFSR NASA-MERRA GFS NCEP-FNL Reanalysis Analysis Ocean surface wind Offshore wind energy Iberian Peninsula Portugal Spain 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. All rights reserved. 1. Introduction Climatic, atmospheric and oceanic modelling applications require accurate oceanic surface wind data to, realistically, represent the oceanic forcing fields and interactions between air and sea. Moreover, data regarding ocean winds is very valuable in the context of offshore wind energy, which is expected to constitute a significant part of the fu- ture wind-derived energy as a whole (Carvalho, Rocha, Gómez-Gesteira, & Santos, 2012; Carvalho, Rocha, Santos, & Pereira, 2013). However, it is known that ocean areas suffer form a strong lack of measured wind data, mainly due to the high costs and technological challenges involved in the installation of wind measuring masts at such sites. Even when in situ data exists (collected on board ships, vessels, moored buoys, etc.) their availability is highly variable both in space and time and cannot be considered as representative of local wind regimes (Risien & Chelton, 2006). Especially for offshore wind resource assessment appli- cations, accurate wind data is a key factor because energetic production is proportional to the wind speed cubed (Bruun, Koch, Horstmann, Hasager, & Nielsen, 2006), making that apparent small inaccuracies in the wind velocity can originate large discrepancies in the expected wind-derived energy production. Thus, it becomes paramount to search and validate alternative data sources to in situ measured wind data over ocean areas. These alternative sources of offshore wind data consist, basically, in satellite-derived mea- surements, data simulated by numerical weather prediction (NWP) models and products that combine observed and NWP simulated data (mainly reanalysis and analysis datasets). While satellite-derived wind data is available at a near-global scale and in a time-continuous way, they are indirect measurements (that is, they are derived from other measurements and processed using complex geophysical models) and Remote Sensing of Environment 152 (2014) 480–492 ⁎ Corresponding author. Tel.: +351 234 370 356; fax: +351 234 378197. E-mail addresses: david.carvalho@ua.pt (D. Carvalho), alfredo.rocha@ua.pt (A. Rocha), mggesteira@uvigo.es (M. Gómez-Gesteira), cmi@isep.ipp.pt (C. Silva Santos). http://dx.doi.org/10.1016/j.rse.2014.07.017 0034-4257/© 2014 Elsevier Inc. All rights reserved. Contents lists available at ScienceDirect Remote Sensing of Environment journal homepage: www.elsevier.com/locate/rse