TY - JOUR

T1 - Climatological mean and interannual variance of United States surface wind speed, direction and velocity

AU - Klink, Katherine

N1 - Copyright:
Copyright 2004 Elsevier Science B.V., Amsterdam. All rights reserved.

PY - 1999

Y1 - 1999

N2 - Means and variances of monthly mean wind speed, direction and velocity (the mean resultant vector) are derived for the period 1961-1990 at 216 stations in the coterminous United States. Direction and velocity means and variances are calculated using a complex-arithmetic extension of the equations for scalar mean and variance. Variance is derived from the 30-year time series of monthly means. While analyses of monthly mean wind fields are common, accompanying analyses of speed, direction, and velocity variance do not generally accompany them. Mean monthly wind direction and velocity fields show a typical seasonal progression from westerly and northwesterly winds in winter, to southerly winds in summer. Scalar and vector wind speeds are highest in winter and spring, and lowest in the summer. Seasonal variation in the mean fields is related to seasonal changes in mean sea level pressure, particularly east of the Rocky Mountains. In the western United States, mean winds often reflect channeling by local topography. The interannual variance of mean monthly wind speed, direction and velocity are related to seasonal variability in synoptic-scale features, such as the frequency of cyclones and anticyclones. Low variance occurs at a number of stations in the west, where topography restricts the range of wind variability. High velocity variance appears when both speed and direction variability are high, but it can occur also when speed variance is high and direction variance is low (or vice versa). Low velocity variance can result from low speed and direction variance, or from low mean wind velocities. The mean and variance characteristics of surface winds provide additional information on the surface climatology of the coterminous United States, and serve as a useful adjunct to other extant land-surface climatologies.

AB - Means and variances of monthly mean wind speed, direction and velocity (the mean resultant vector) are derived for the period 1961-1990 at 216 stations in the coterminous United States. Direction and velocity means and variances are calculated using a complex-arithmetic extension of the equations for scalar mean and variance. Variance is derived from the 30-year time series of monthly means. While analyses of monthly mean wind fields are common, accompanying analyses of speed, direction, and velocity variance do not generally accompany them. Mean monthly wind direction and velocity fields show a typical seasonal progression from westerly and northwesterly winds in winter, to southerly winds in summer. Scalar and vector wind speeds are highest in winter and spring, and lowest in the summer. Seasonal variation in the mean fields is related to seasonal changes in mean sea level pressure, particularly east of the Rocky Mountains. In the western United States, mean winds often reflect channeling by local topography. The interannual variance of mean monthly wind speed, direction and velocity are related to seasonal variability in synoptic-scale features, such as the frequency of cyclones and anticyclones. Low variance occurs at a number of stations in the west, where topography restricts the range of wind variability. High velocity variance appears when both speed and direction variability are high, but it can occur also when speed variance is high and direction variance is low (or vice versa). Low velocity variance can result from low speed and direction variance, or from low mean wind velocities. The mean and variance characteristics of surface winds provide additional information on the surface climatology of the coterminous United States, and serve as a useful adjunct to other extant land-surface climatologies.

KW - Directional and vector statistics

KW - USA

KW - Wind direction

KW - Wind speed

KW - Wind velocity

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U2 - 10.1002/(SICI)1097-0088(199904)19:5<471::AID-JOC367>3.0.CO;2-X

DO - 10.1002/(SICI)1097-0088(199904)19:5<471::AID-JOC367>3.0.CO;2-X

M3 - Article

AN - SCOPUS:0033020310

VL - 19

SP - 471

EP - 488

JO - International Journal of Climatology

JF - International Journal of Climatology

SN - 0899-8418

IS - 5

ER -