1. Institute of Energy Systems, School of Engineering and Electronics, University of Edinburgh, EH9 3JL, UK
2. Atmospheric Science Program, Department of Geography, Indiana University, Bloomington, IN 47405, USA
3. Wind Energy Department, Risø National Laboratory, 4000 Roskilde, Denmark
4. Technical University of Denmark, Department of Mechanical Engineering Fluid Mechanics Section, Building 403, DK-2800 Lyngby, Denmark