Coriolis effects on wind jets and cloudiness along coasts

Orr, Andrew; Hunt, J. C. R.; Capon, R.; Sommeria, Joël; Cresswell, Doug; Owinoh, Antony

doi:10.1256/wea.219.04

Cited by 28 publications

(33 citation statements)

References 26 publications

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“…Another problem of simulating the interaction between the Coriolis force and a wind farm wake in LES is that one might need to simulate a very long time in order to obtain a statistically independent average of a small quantify such as the wind direction deflection in neutral atmospheric conditions. Mitraszewski (2012) argued that a wind farm can be seen as a roughness change, and therefore the Coriolis force should turn the wind farm wake anticlockwise, following Orr et al (2005). In contradiction to Mitraszewski (2012), it was shown in previous work (van der Laan et al, 2015a) that the Coriolis force turns a wind farm wake clockwise (in neutral atmospheric conditions), and this is explained as a result of a stream-wise decreasing Coriolis force in the wake recovery region.…”

Section: Introductionmentioning

confidence: 92%

Why the Coriolis force turns a wind farm wake clockwise in the Northern Hemisphere

Laan

Sørensen²

2017

Wind Energ. Sci.

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Abstract.The interaction between the Coriolis force and a wind farm wake is investigated by Reynoldsaveraged Navier-Stokes simulations, using two different wind farm representations: a high roughness and 5 × 5 actuator disks. Surprisingly, the calculated wind farm wake deflection is the opposite in the two simulations. A momentum balance in the cross flow direction shows that the interaction between the Coriolis force and the 5 × 5 actuator disks is complex due to turbulent mixing of veered momentum from above into the wind farm, which is not observed for the interaction between the Coriolis force and a roughness change. When the wind farm simulations are performed with a horizontally constant Coriolis force in order to isolate the effect of the wind veer, the wind farm wake deflection of the 5 × 5 actuator disks simulation remains unchanged. This proves that the present wind veer deflects the wind farm wake and not the local changes in the Coriolis force in the wake deficit region. An additional simulation of a single actuator disk, operating in a shallow atmospheric boundary layer, confirms that the Coriolis force indirectly turns a wind turbine wake clockwise, as observed from above, due to the presence of a strong wind veer.

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Section: Introductionmentioning

confidence: 92%

Why the Coriolis force turns a wind farm wake clockwise in the Northern Hemisphere

Laan

Sørensen²

2017

Wind Energ. Sci.

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“…The peak winds at this time are indeed around the northern end of the South Island, but the most striking large-scale feature is the broad jet downstream of the Cook Strait, which has a peak speed of around 30 m s −1 . Orr et al (2005) have suggested that such a downstream jet may be the result of the channelling effect created when a low Froude number flow impinges on the abrupt changes in surface roughness and orography typically associated with a strait. Indeed, the ability of the UM to capture this type of channelling effect has already been demonstrated for the Straits of Dover by Capon (2003).…”

Section: -M Windsmentioning

confidence: 99%

A high‐resolution modelling case study of a severe weather event over New Zealand

Webster

Uddstrom

Oliver

et al. 2008

Atmospheric Science Letters

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In this article, the ability of the Met Office Unified Model to simulate the severe weather over the South Island of New Zealand, on 8 January 2004 is investigated. Simulations were run at horizontal resolutions of between 60 and 1 km. The modelled broad-scale rainfall and wind features, most notably the area-averaged accumulated rainfall, were found to converge with resolution. At the highest resolutions, all the observed rainfall and wind features of this event were captured well by the model. Even the 12-km-resolution model is able to resolve the broad elongated ridge-like structure of the Southern Alps and qualitatively capture the main features of the rainfall and wind fields.

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“…These synoptic winds are often blocked by the elevated coastal terrain which typifies East Antarctica, resulting in the formation of strong coast‐parallel winds known as barrier jets [ Steinhoff et al , ; Nigro et al , ]. The interaction between winds and abrupt variations in topography, surface roughness, and temperature (e.g., at the interface between sea and land) can also create localized variations in the wind field such as coastal and detached jets, which can only be represented by high‐resolution models [ Hunt et al , ; Owinoh et al , ; Orr et al , ; Turner et al , ].…”

Section: Introductionmentioning

confidence: 99%

Observations and fine‐scale model simulations of gravity waves over Davis, East Antarctica (69°S, 78°E)

et al. 2017

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Large vertical velocities were observed throughout the troposphere at Davis, East Antarctica, on 18 February 2014 by a VHF wind‐profiling radar. Simulations using the Met Office Unified Model at 2.2, 0.5, and 0.1 km horizontal grid spacing were able to broadly capture the location, timing, and magnitude of the observed velocities, as well as reveal that they are due to small‐scale orographic gravity waves resulting from the interaction between the coastal topography and strong easterly winds associated with a synoptic‐scale cyclone situated to the north. The simulations indicated that the gravity waves are responsible for (i) temperature fluctuations which coincided with satellite‐observed cloud variations in the vicinity of Davis, suggesting that they have a crucial role in the formation of cirrus clouds, and (ii) large vertical momentum fluxes in the troposphere. The waves are prevented from propagating into the stratosphere by the background winds turning from near‐surface easterlies to lower stratospheric northerlies. As well as illuminating and quantifying the role that weather systems have in producing orographic gravity waves along the East Antarctic coastline, studies such as this should be exploited to improve the representation of key localized atmospheric processes in global climate models.

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Coriolis effects on wind jets and cloudiness along coasts

Cited by 28 publications

References 26 publications

Why the Coriolis force turns a wind farm wake clockwise in the Northern Hemisphere

Why the Coriolis force turns a wind farm wake clockwise in the Northern Hemisphere

A high‐resolution modelling case study of a severe weather event over New Zealand

Observations and fine‐scale model simulations of gravity waves over Davis, East Antarctica (69°S, 78°E)

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