Identification

Title

Intermittent turbulence associated with a density current passage in the stable boundary layer

Abstract

Using the unprecedented observational capabilities deployed during the Cooperative Atmosphere-Surface Exchange Study-99 (CASES-99), we found three distinct turbulence events on the night of 18 October 1999, each of which was associated with different phenomena: a density current, solitary waves, and downward propagating waves from a low-level jet. In this study, we focus on the first event, the density current and its associated intermittent turbulence. As the cold density current propagated through the CASES-99 site, eddy motions in the upper part of the density current led to periodic overturning of the stratified flow, local thermal instability and a downward diffusion of turbulent mixing. Propagation of the density current induced a secondary circulation. The descending motion following the head of the density current resulted in strong stratification, a sharp reduction in the turbulence, and a sudden increase in the wind speed. As the wind surge propagated toward the surface, shear instability generated upward diffusion of turbulent mixing. We demonstrate in detail that the height and sequence of the local thermal and shear instabilities associated with the dynamics of the density current are responsible for the apparent intermittent turbulence.

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.org/ark:/85065/d7rb7521

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

Keyword set

keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

West bounding longitude

East bounding longitude

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South bounding latitude

Temporal reference

Temporal extent

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End position

Dataset reference date

date type

publication

effective date

2002-11-01T00:00:00Z

Frequency of update

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Conformity

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version of format

Constraints related to access and use

Constraint set

Use constraints

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact