Identification

Title

A Modelling study of flux imbalance and the influence of entrainment in the convective boundary layer

Abstract

It is frequently observed in field experiments that the eddy covariance heat fluxes are systematically underestimated as compared to the available energy. The flux imbalance problem is investigated using the NCARâ€™s large-eddy simulation (LES) model imbedded with an online scheme to calculate Reynolds-averaged fluxes. A top-down and a bottom-up tracer are implemented into the LES model to quantify the influence of entrainment and bottom-up diffusion processes on flux imbalance. The results show that the flux imbalance follows a set of universal functions that capture the exponential decreasing dependence on u */w *, where u * and w * are friction velocity and the convective velocity scale, respectively, and an elliptic relationship to z/z i , where z i is the mixing-layer height. The source location in the boundary layer is an important factor controlling the imbalance magnitude and its horizontal and vertical distributions. The flux imbalance of heat and the bottom-up tracer is tightly related to turbulent coherent structures, whereas for the top-down diffusion, such relations are weak to nonexistent. Our results are broadly consistent with previous studies on the flux imbalance problem, suggesting that the published results are robust and are not artefacts of numerical schemes.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7j104ht

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

North bounding latitude

South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2008-05-01T00:00:00Z

Frequency of update

Quality and validity

Lineage

Conformity

Data format

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Constraints related to access and use

Constraint set

Use constraints

An edited version of this paper was published by Springer. Copyright Springer Science+Business Media B.V. 2008.

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