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

Larry Mahrt, Christoph Thomas, Scott Richardson, Nelson Seaman, David Stauffer, Matthias Zeeman

Research output: Contribution to journalArticle

46 Scopus citations

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.

Original languageEnglish (US)
Pages (from-to)179-199
Number of pages21
JournalBoundary-Layer Meteorology
Volume147
Issue number2
DOIs
StatePublished - May 2013

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

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