Lead Session Chair:
Stephan Barth, Managing Director, ForWind - Center for Wind Energy Research, Germany
(1) DTU, Roskilde, Denmark
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Presenter's biographyBiographies are supplied directly by presenters at OFFSHORE 2015 and are published here unedited
Alfredo is a Senior Scientist at DTU Wind Energy, Denmark. His work has mainly been focused on the study of boundary-layer winds and remote sensing technology. He has been involved in many other aspects of wind power meteorology which include turbulence, wakes and the use of numerical weather prediction models for wind energy. He has a degree in Mechanical Engineering, a Master in Mechanical Engineering, a Master in Renewable Energies and did his PhD at Risø
Understanding the role of baroclinity on the wind in the northern seas' coastal areas
Coastal areas are challenging for flow modeling (perhaps even more than complex terrain "traditional" areas like mountainous terrain and forested areas) as different atmospheric and marine phenomena are taking place at different scales. Abrupt changes in surface roughness, interaction between wind and waves, high horizontal and vertical temperature gradients are just few examples of such phenomena, which in many cases are unique for this type of areas. Coastal areas are however very attractive for wind energy because the wind resource is generally higher than that over land and the cost is much lower compared to that of “more offshore” projects.
Our idea is to look at one particular physical phenomenon, baroclinity, which often occurs in coastal areas. Baroclinity is normally regarded to the change of geostrophic wind with height and so the strength of baroclinity is related to the strength of the horizontal temperature gradients (thermal wind). This phenomenon is commonly neglected in microscale flow modelling as at such scales other effects are generally more important when predicting winds close to the surface. At coastal areas, baroclinity can indeed have a stronger effect on both wind shear and wind veer already at heights where turbines are operating.
Main body of abstract
Based on a 32-year mesoscale model simulation performed over a large area covering North Europe, we show the effect of baroclinity on the wind, particularly at the coastal areas in the Dutch, German and Danish North Sea and Danish, Swedish and German Baltic Sea and at different heights where turbines currently operate. The simulations are performed using the advanced Weather Research and Forecasting (WRF) model with the smallest domain having a 2-km horizontal resolution. The thermal wind is derived from the large-scale gradients of geopotential difference between the model outputs at different levels.
This analysis shows that:
1. The mesoscale model simulations can be used to derive the thermal wind and thus its effect on the boundary-layer wind
2. The thermal wind is an important component especially looking at coastal areas where horizontal temperature gradients can be large
3. Baroclinity needs to be accounted for in microscale models if we want to accurate predict winds at coastal sites where many offshore wind projects are being designed
We would like that the audience:
1. Understands the concept of baroclinity and thermal wind
2. Understands the importance of baroclinity in the context of wind energy particularly in coastal areas
3. Obtains a good impression of the capabilities that mesoscale models have to resolve complex phenomena