AbstractsGeography &GIS

Multi-scale atmospheric and climate phenomena in the context of the wind resource assessment: a case study in complex, coastal terrain

by Peter Bernard Gibson

Institution: University of Otago
Year: 0
Keywords: wind resource; atmospheric circulation; Kidson types; TAPM; synoptic; mesoscale; microscale; complex terrain
Record ID: 1316133
Full text PDF: http://hdl.handle.net/10523/4919


This thesis examines aspects of the wind resource potential (the potential for energy conversion by wind turbines) in a complex, coastal terrain setting. The main objective of this study is to use a combined modelling and field based measurement approach to assess how atmospheric and climate phenomena, over a range of spatial-temporal scales, can contribute to the quantity and quality of the wind resource in a complex, coastal terrain setting. A major theme of this study is the adoption of a holistic approach, to include the examination of atmospheric and climate phenomena that are characterized over a range of spatial-temporal scales, including those at the synoptic, mesoscale and microscale. Studies aimed at establishing linkages between aspects of the wind resource and atmospheric and climate phenomena remain sparse, in both the international and New Zealand focused published literature. However, establishing and quantifying these linkages carry important practical and economic implications including: forecasting the energy extractable by wind turbines over short time periods; allowing better informed decisions regarding turbine placement to be made; and understanding how the wind resource will be affected by 21st century climate change. These implications are particularly important given the recent and forecasted growth rate of wind energy developments both globally and within New Zealand. The methods adopted in this research involved a field based measurement campaign combined with mesoscale numerical modelling. This research was conducted on the ridge top of Porteous Hill (approximately 400m a.s.l) (45.6895° S; 170.5829° E) situated near to the township of Waitati, north of Dunedin. The choice of field site, within a complex and coastal terrain setting, permitted examination of a number of atmospheric processes and phenomena, operating over a range of spatial-temporal scales, potentially important to the wind resource in such a geographical setting. Data from four ridge top temporary automatic weather stations were used in this research, including a sonic anemometer to analyse properties of the near surface ridge top turbulence. Measurements from these stations were made at several different heights above the surface which ranged from 2m to 30m, and across different time periods between 1 September 2011 and 31 August 2013. The Air Pollution Model (TAPM) was also used in this study; TAPM was employed to test model skill in calculating metrics for wind resource quantity and to untangle linkages between processes and phenomena that operate over different scales. Substantial variability in the monthly mean power density (a commonly used metric for wind resource quantity) was found between months over the two year examination period. Changes in the mean power density between months were linked to anomalous Southern Hemispheric monthly mean sea level pressure fields derived from reanalysis data. In particular, the wind resource quantity in a given month examined was enhanced when high pressure centres were…