A statistical model of the seasonal-diurnal wind climate at Adelaide

Abstract

The seasonal-diurnal variation of surface winds observed at Adelaide Airport (South Australia) over 40 years is modelled in terms of the zonal-meridional wind vectors. Calms are assessed separately from the wind vectors. The joint probability density function of the wind vectors is modelled as the sum of a number of disjoint bivariate normal distributions in the zonal-meridional plane. An overview of the data suggests three diurnal mechanisms: sea-to-land breezes, land-to-sea breezes and downslope drainage flows off the Adelaide Hills, together with two non-diurnal large-scale weather mechanisms that are modulated by the annual migration of the sub-tropical ridge. It is shown that, typically, two of the three diurnal components contribute to the joint probability density function for any given hour of day and month, together with the two large-scale weather components. Optimisation is used to quantify the model parameters directly from the joint probability density function. The robustness of the methodology is verified using standard "Bootstrapping" methods. The model elucidates the principal climate mechanisms at Adelaide in terms of the seasonaldiurnal variation of the joint statistics of wind speed and direction using just the mean, annual, semi-annual, diurnal and semi-diurnal harmonics.

Parameterizing the seasonal–diurnal wind climate of Rome: Fiumicino and Ciampino

“…Apart from the earlier OEN analysis for Adelaide (Cook, ), no other published studies dissect the seasonal–diurnal wind vectors in such fine detail. A major difficulty in reporting this study has been in presenting multidimensional data on the two‐dimensional page without losing too much information.…”

“…Elevation contours labelled at 50 m intervals 2002) show clockwise, anticlockwise or no rotation. The consensus (Cook, 2015b) is that rotation is controlled by a "delicate balance" of Coriolis forces, pressure gradients, orography and advection effects. Figure 3 enlarges and annotates the p(θ) plots for the strong sea/land breeze cycle in July.…”

“…In contrast with the earlier OEN analysis for Adelaide (Cook, 2015b), which is subject to the strong depressions of the Southern Ocean, cyclonic activity in the Mediterranean is much weaker. A few mature Atlantic depressions pass over Spain and are steered by the Alps into the Ligurian and Tyrrhenian seas to affect northern Italy.…”

“…Brittain (1966) reports that a sea breeze circulation will not form in winds > 15 kn (7.5 mÁs -1 ), but a light offshore wind assists, whilst an onshore wind inhibits, its formation. Cook (2015b) applied the OEN model to the seasonaldiurnal wind climate at Adelaide, South Australia, where it correctly identified the known physical components of the climate: local and continental sea breezes, land breezes, katabatic winds (Physick and Byron-Scott, 1977;Masouleh et al, 2016) and two geostrophic wind components.…”

A novel probability density function applied to wind characterization in order to evaluate the wind power potential in Tungurahua, Ecuador’s Andean region

“…From Figure 4(a), it can be seen that the daily wind pattern is characterized by the existence of a night calm, and a halfsine like velocity profile during light hours. This behavior is found in other locations (Buflasa et al, 2008;Cook, 2015). Thus, instead of a timeless PDF, the information provided by the daily wind velocity profile may be used as the base for the construction a daily-based PDF.…”