edu.ucar.opensky::articles:6513 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-26T15:18:01.242914 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7vh5p1p An observational and numerical study of a regional-scale downslope flow in northern Arizona 2008-07-22T00:00:00Z publication https://n2t.org/ark:/85065/d7vh5p1p https://doi.org/10.1029/2007JD009623 Savage, L. author Zhong, S. author Yao, W. author Brown, William O.J. author Horst, Thomas W. author Whiteman, C. author UCAR/NCAR - Library publisher Boundary layer observations taken during the METCRAX field study in October of 2006 near Winslow in Northern Arizona revealed the frequent presence of a near-surface wind maximum on nights with relatively quiescent synoptic conditions. Data from a sodar, a radar wind profiler, several surface stations, and frequent high-resolution rawinsonde soundings were used to characterize this boundary layer wind phenomenon and its relation to synoptic conditions and the ambient environment. The data analyses are augmented by high-resolution mesoscale numerical modeling. It is found that the observed nocturnal low-level wind maximum is part of a regional-scale downslope flow converging from high terrain of the Colorado Plateau toward the Little Colorado River Valley. The depth of this downslope flow is between 100 and 250 m with a peak speed of 4 - 6 m s⁻¹occurring usually within the lowest 50 m above ground. Opposing ambient winds lead to a longer evening transition period, shallower slope flows, and a smaller horizontal extent as compared to supporting synoptic winds. A simple analytical solution based on local equilibrium appears to agree fairly well with the observed layer mean downslope wind speed, but the classic Prandtl solution for maximum downslope wind speed fails to match the observations. The properties of the flow appear to be insensitive to changes in soil moisture, land cover, and surface roughness length. The contribution to the low-level wind maximum by inertial oscillation at night is found to be insignificant. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication An edited version of this paper was published by AGU. Copyright 2008 American Geophysical Union. None eng geoscientificInformation