Cluster-Analysis Classification of Wintertime Wind Patterns in the Grand Canyon Region

Twelve typical wintertime wind patterns for the Grand Canyon region were derived from a two-stage cluster analysis wind-field classification scheme. The wind measurements were collected by a surface network of 15 stations deployed for a period of approximately three months. The wind patterns are strongly influenced by the complex terrain of the region. The analyses relate the wind patterns to meteorological conditions, providing insight into the physical processes generating the wind fields. Most patterns have a distinct diurnal cycle, caused by thermally induced winds near the ground. They provide evidence that thermally forced flows are important in winter and are not easily overridden by ambient flows. Some patterns differ primarily in the ratio of highand low-elevation site wind speeds, indicating the importance of decoupling of the low-elevation winds in this basin area from the stronger ambient winds.