An observational study of the structure of the nocturnal urban boundary layer

Itsushi Uno, S. Wakamatsu, H. Ueda, A. Nakamura

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

The formation mechanism of the nocturnal urban boundary layer (UBL), especially in the winter nighttime, was investigated based on the extensive field observations conducted during November 1984 in Sapporo, Japan. A strong, elevated inversion formed over the Sapporo urban area and the inversion base height was approximately twice the average building height. Velocity fluctuations Σu, Σw and Reynolds stress {Mathematical expression} had nearly uniform profiles within the nocturnal UBL and decreased with height above the UBL. On the other hand, temperature fluctuations Σt, and heat fluxes {Mathematical expression} and {Mathematical expression} had peaks at the inversion base and small values within the nocturnal UBL. The turbulent kinetic energy budget showed that the turbulent transport term and shear generation from urban canopy elements are important in the nocturnal UBL development; the role of the buoyancy term is small. The turbulence data analysis and application of a simple advective model showed that the mechanism of UBL formation may be controlled by the downward transport of sensible heat from the elevated inversion caused by mechanically-generated turbulence.

Original languageEnglish
Pages (from-to)59-82
Number of pages24
JournalBoundary-Layer Meteorology
Volume45
Issue number1-2
DOIs
Publication statusPublished - Oct 1 1988
Externally publishedYes

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boundary layer
turbulence
formation mechanism
energy budget
buoyancy
kinetic energy
heat flux
urban area
canopy
inversion
winter
temperature

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

Cite this

An observational study of the structure of the nocturnal urban boundary layer. / Uno, Itsushi; Wakamatsu, S.; Ueda, H.; Nakamura, A.

In: Boundary-Layer Meteorology, Vol. 45, No. 1-2, 01.10.1988, p. 59-82.

Research output: Contribution to journalArticle

Uno, Itsushi ; Wakamatsu, S. ; Ueda, H. ; Nakamura, A. / An observational study of the structure of the nocturnal urban boundary layer. In: Boundary-Layer Meteorology. 1988 ; Vol. 45, No. 1-2. pp. 59-82.
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