Boundary-Layer Meteorology

, Volume 147, Issue 2, pp 179–199

Non-stationary Generation of Weak Turbulence for Very Stable and Weak-Wind Conditions

Authors

    • CEOASOregon State University
  • Christoph Thomas
    • CEOASOregon State University
  • Scott Richardson
    • Department of MeteorologyPennsylvania State University
  • Nelson Seaman
    • Department of MeteorologyPennsylvania State University
  • David Stauffer
    • Department of MeteorologyPennsylvania State University
  • Matthias Zeeman
    • Institute of Meteorology and Climate Research (IMK-IFU)Karlsruhe Institute of Technology (KIT)
Open AccessArticle

DOI: 10.1007/s10546-012-9782-x

Cite this article as:
Mahrt, L., Thomas, C., Richardson, S. et al. Boundary-Layer Meteorol (2013) 147: 179. doi:10.1007/s10546-012-9782-x

Abstract

Turbulence measurements for very stable conditions near the surface are contrasted among three sites: a high altitude basin during winter with grass or snow-covered grass, a broad valley with complex agricultural land use, and a more narrow valley that is influenced by a valley cold pool and cold air drainage. In contrast to previous studies, this investigation emphasizes the very weak turbulence with large bulk Richardson number occurring during extensive periods between brief mixing events. The relationship of the turbulence to the non-stationary wind and stratification is examined along with the impact of short-term flow accelerations, directional shear and downward diffusion of turbulence from higher levels. The failure of the turbulence for strong stratification to decrease with further increase of stratification is explored. Additional analyses are applied to weak-wind cases for the entire range of stratification, including weak stratification associated with cloudy conditions.

Keywords

Intermittent turbulenceNocturnal boundary layerStable boundary layerSubmesoWeak winds
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© The Author(s) 2012

Open AccessThis article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.