Monin–Obukhov length: Difference between revisions
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The [http://amsglossary.allenpress.com/glossary/search?id=obukhov-length1 Obukhov length] is used to describe the effects of buoyancy on turbulent flows, particularly in the lower tenth of the [[atmospheric boundary layer]]. It was first defined by [[Alexander Obukhov]]<ref>{{cite book|last=Jacobson|first=Mark Z.|title=Fundamentals of Atmospheric Modeling|url=http://books.google.co.in/books?id=WPwEf-1f73wC&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false|edition=2|year=2005|publisher=[[Cambridge University Press]]}}</ref> in 1946,<ref>{{cite journal |last1=Obukhov |first1=A.M.|year=1946|title=Turbulence in an atmosphere with a non- uniform temperature.|journal= Tr. Inst. Teor. Geofiz. Akad. Nauk. SSSR|volume=1|pages=95–115}}</ref> <ref>{{cite journal |last1=Obukhov |first1=A.M.|year=1971|title=Turbulence in an atmosphere with a non-uniform temperature (English Translation)| journal=Boundary-Layer Meteorology|volume=2| pages=7-29}}</ref>. It is also known as the Monin-Obukhov length because of its important role in the similarity theory developed by Monin and Obukhov <ref>{{cite journal |last1=Monin|first1=A.S.|last2=Obukhov |first2=A.M.|year=1954|title=Basic laws of turbulent mixing in the surface layer of the atmosphere.|journal= Tr. Akad. Nauk SSSR Geofiz. Inst|volume=24|pages=163-187}}</ref>. |
The [http://amsglossary.allenpress.com/glossary/search?id=obukhov-length1 Obukhov length] is used to describe the effects of buoyancy on turbulent flows, particularly in the lower tenth of the [[atmospheric boundary layer]]. It was first defined by [[Alexander Obukhov]]<ref>{{cite book|last=Jacobson|first=Mark Z.|title=Fundamentals of Atmospheric Modeling|url=http://books.google.co.in/books?id=WPwEf-1f73wC&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false|edition=2|year=2005|publisher=[[Cambridge University Press]]}}</ref> in 1946,<ref>{{cite journal |last1=Obukhov |first1=A.M.|year=1946|title=Turbulence in an atmosphere with a non- uniform temperature.|journal= Tr. Inst. Teor. Geofiz. Akad. Nauk. SSSR|volume=1|pages=95–115}}</ref> <ref>{{cite journal |last1=Obukhov |first1=A.M.|year=1971|title=Turbulence in an atmosphere with a non-uniform temperature (English Translation)| journal=Boundary-Layer Meteorology|volume=2| pages=7-29|bibcode = 1971BoLMe...2....7O |doi = 10.1007/BF00718085 }}</ref>. It is also known as the Monin-Obukhov length because of its important role in the similarity theory developed by Monin and Obukhov <ref>{{cite journal |last1=Monin|first1=A.S.|last2=Obukhov |first2=A.M.|year=1954|title=Basic laws of turbulent mixing in the surface layer of the atmosphere.|journal= Tr. Akad. Nauk SSSR Geofiz. Inst|volume=24|pages=163-187}}</ref>. |
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The '''Obukhov Length''' is defined by |
The '''Obukhov Length''' is defined by |
Revision as of 03:45, 16 August 2011
This article needs additional citations for verification. (December 2009) |
The Obukhov length is used to describe the effects of buoyancy on turbulent flows, particularly in the lower tenth of the atmospheric boundary layer. It was first defined by Alexander Obukhov[1] in 1946,[2] [3]. It is also known as the Monin-Obukhov length because of its important role in the similarity theory developed by Monin and Obukhov [4].
The Obukhov Length is defined by
where is the frictional velocity, is the mean virtual potential temperature, is the surface virtual potential temperature flux, k is the von Kármán constant. The virtual potential temperature flux is given by
where is potential temperature, is absolute temperature and is specific humidity.
By this definition, is usually negative in the daytime since is typically positive during the daytime over land, positive at night when is typically negative, and becomes infinite at dawn and dusk when passes through zero.
A physical interpretation of is given by the Monin-Obukhov similarity theory. During the day it is the height at which the buoyant production of turbulence kinetic energy (TKE) is equal to that produced by the shearing action of the wind (shear production of TKE).
References
- ^ Jacobson, Mark Z. (2005). Fundamentals of Atmospheric Modeling (2 ed.). Cambridge University Press.
- ^ Obukhov, A.M. (1946). "Turbulence in an atmosphere with a non- uniform temperature". Tr. Inst. Teor. Geofiz. Akad. Nauk. SSSR. 1: 95–115.
- ^ Obukhov, A.M. (1971). "Turbulence in an atmosphere with a non-uniform temperature (English Translation)". Boundary-Layer Meteorology. 2: 7–29. Bibcode:1971BoLMe...2....7O. doi:10.1007/BF00718085.
- ^ Monin, A.S.; Obukhov, A.M. (1954). "Basic laws of turbulent mixing in the surface layer of the atmosphere". Tr. Akad. Nauk SSSR Geofiz. Inst. 24: 163–187.