Two-dimensional numerical analysis of a thermally generated mesoscale wind system observed in the Mackenzie Basin, New Zealand

In the past four decades, the importance of local air circulations for air pollution transport, weather forecasting, and land-use management has been realised. Thermally driven circulations, such as sea-breezes and diurnal orographically induced winds, result from interplay between topographic and thermal forcings. Over simple flat terrain, these wind systems can be forecast with a high degree of skill since the underlying physical mechanisms that drive them are well understood, and adequately formulated in atmospheric models. An extensive set of earlier literature reviews is provided by Defant (1951) and Flohn (1969), while books by Oke (1992), Atkinson (1981), Barry (1992) and Whiteman (2000) provide suitable in-depth description of these wind systems. In New Zealand, observational studies of thermally driven circulations have been reported by McGowan et al. (1995), McGowan and Sturman (1996) and Kossmann et al. (2002). Kossmann et al. (2002) provided a comprehensive analysis of the thermodynamics of local wind systems in the Lake Tekapo region situated in the Mackenzie Basin of the South Island. Numerical analysis of these circulations, using the Regional Atmospheric Modelling System (RAMS; Pielke et al. 1992), has also been described by Zawar-Reza (2000) and Zawar-Reza et al. (2004). Aust. Met. Mag. 55 (2006) 19-34