geostrophic wind


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geostrophic wind

[¦jē·ō¦sträf·ik ′wind]
(meteorology)
That horizontal wind velocity for which the Coriolis acceleration exactly balances the horizontal pressure force.

Geostrophic Wind

 

a horizontal, even, and straight movement of air with no force of friction and with balance in the gradient of pressure and the deflecting force of the earth’s rotation; the simplest theoretical scheme of air movement of the rotating earth. The actual wind in atmospheric layers higher than 1 km above the earth’s surface is close to the geostrophic wind. The geostrophic wind is directed along the isobar, with an area of low pressure remaining to the left of the stream in the northern hemisphere and to the right in the southern. The velocity of the geostrophic wind is proportional to the magnitude of the horizontal gradient of pressure. With equal gradients it is inversely proportional to the density of the air and the sine of geographic latitude and therefore increases with elevation and with increasing nearness to the equator.

geostrophic wind

geostrophic wind
Pressure-gradient force causes air parcel to accelerate. Coriolis begins deflecting air to the right. Coriolis increases as speed increases. Coriolis eventually balances pressure gradient forces.
That horizontal wind velocity for which the Coriolis acceleration exactly balances the horizontal pressure or gradient force.
References in periodicals archive ?
In particular, the abrupt change in the air flow, evaluated from geostrophic wind fields (Soomere and Raamet, 2014), signals a major change in the air pressure and upper-level wind system over the southern Baltic Sea in 1988.
The wave model was forced with wind data corresponding to an elevation of 10 m above the sea surface, constructed from the Swedish Meteorological and Hydrological Institute (SMHI) geostrophic wind database.
This is a consequence offriction entering into the geostrophic wind equation; since Coriolis is velocity dependent it reduces its effect in the balance between Coriolis and pressure gradient, which acts toward the right, so instead of blowing south to north, it becomes increasingly southwest to northeast and so on.
Figure 6 shows the 500/1000 thickness advection by geostrophic wind of 1000 hpa level in the selected case studies to represent.
The most popular way consists in the use of geostrophic wind fields that are adjusted to the 10 m level by means of a simplified procedure in which the geostrophic wind speed (usually retrieved from the Swedish Meteorological and Hydrological Institute database) was multiplied by 0.
g = [delta]], where the velocity is equal to the geostrophic wind velocity G.
Assuming flat and homogeneous terrain, and constant geostrophic wind, the diurnal wind variability is reduced along the vertical direction.
With regard to vertical shear, the vertical derivative of the geostrophic wind is directly related to the horizontal temperature gradient, which is why it is called the thermal wind shear.
The wind forcing at a 10 m level was derived from geostrophic winds as recommended by Bumke and Hasse (1989): the geostrophic wind speed was multiplied by 0.
2009) which thus can be considered as the best compromise between robustness and low spatial resolution of the geostrophic wind data, and the potential distortions of the local wind field in higher-resolution local atmospheric models (Ansper & Fortelius 2003; Keevallik et al.
The direction of the geostrophic wind relative to the slope was incremented by 45[degrees] in each successive run.
20CR, on the other hand, seems to underestimate the wind speeds at 800 hPa: a rough calculation of the geostrophic wind speed in the region of the two stations with the strongest winds in Fig.