### Abstract

Coherent structures in the atmospheric boundary layer are fundamental to the transport of momentum and heat as well as to the production of turbulence. The present work attempts to investigate the behavior of the inclination angle of the vortex packet structures ((Formula presented.)) under different stability conditions. The data were collected from the Marine Ecosystem Research Centre (EKOMAR) site at the east coast of Peninsular Malaysia. The main measurements were conducted by placing two hotwires 3 and 12 m above ground. The two-point correlation method was used to calculate the vortex packet structure inclination angle, while the one-point correlation method was employed to calculate its length-scale. The inclination angle was found to increase under both stable and unstable conditions. As the Obukhov stability parameter ((Formula presented.)) approaches 0, the inclination angle ranged between (Formula presented.) to (Formula presented.) for the stable and unstable conditions, respectively, which agrees with the findings of previous research. The vertical gradient of velocity is the dominant parameter affecting the inclination angle under different stability conditions.

Original language | English |
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Pages (from-to) | 1-23 |

Number of pages | 23 |

Journal | Environmental Fluid Mechanics |

DOIs | |

Publication status | Accepted/In press - 11 Nov 2017 |

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### Keywords

- Atmospheric boundary layer
- Coherent structure
- Inclination angle
- Turbulence

### ASJC Scopus subject areas

- Environmental Chemistry
- Water Science and Technology

### Cite this

**Effect of atmospheric boundary layer stability on the inclination angle of turbulence coherent structures.** / Lotfy, Eslam Reda; Harun, Zambri.

Research output: Contribution to journal › Article

}

TY - JOUR

T1 - Effect of atmospheric boundary layer stability on the inclination angle of turbulence coherent structures

AU - Lotfy, Eslam Reda

AU - Harun, Zambri

PY - 2017/11/11

Y1 - 2017/11/11

N2 - Coherent structures in the atmospheric boundary layer are fundamental to the transport of momentum and heat as well as to the production of turbulence. The present work attempts to investigate the behavior of the inclination angle of the vortex packet structures ((Formula presented.)) under different stability conditions. The data were collected from the Marine Ecosystem Research Centre (EKOMAR) site at the east coast of Peninsular Malaysia. The main measurements were conducted by placing two hotwires 3 and 12 m above ground. The two-point correlation method was used to calculate the vortex packet structure inclination angle, while the one-point correlation method was employed to calculate its length-scale. The inclination angle was found to increase under both stable and unstable conditions. As the Obukhov stability parameter ((Formula presented.)) approaches 0, the inclination angle ranged between (Formula presented.) to (Formula presented.) for the stable and unstable conditions, respectively, which agrees with the findings of previous research. The vertical gradient of velocity is the dominant parameter affecting the inclination angle under different stability conditions.

AB - Coherent structures in the atmospheric boundary layer are fundamental to the transport of momentum and heat as well as to the production of turbulence. The present work attempts to investigate the behavior of the inclination angle of the vortex packet structures ((Formula presented.)) under different stability conditions. The data were collected from the Marine Ecosystem Research Centre (EKOMAR) site at the east coast of Peninsular Malaysia. The main measurements were conducted by placing two hotwires 3 and 12 m above ground. The two-point correlation method was used to calculate the vortex packet structure inclination angle, while the one-point correlation method was employed to calculate its length-scale. The inclination angle was found to increase under both stable and unstable conditions. As the Obukhov stability parameter ((Formula presented.)) approaches 0, the inclination angle ranged between (Formula presented.) to (Formula presented.) for the stable and unstable conditions, respectively, which agrees with the findings of previous research. The vertical gradient of velocity is the dominant parameter affecting the inclination angle under different stability conditions.

KW - Atmospheric boundary layer

KW - Coherent structure

KW - Inclination angle

KW - Turbulence

UR - http://www.scopus.com/inward/record.url?scp=85033432702&partnerID=8YFLogxK

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U2 - 10.1007/s10652-017-9558-4

DO - 10.1007/s10652-017-9558-4

M3 - Article

SP - 1

EP - 23

JO - Environmental Fluid Mechanics

JF - Environmental Fluid Mechanics

SN - 1567-7419

ER -