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Passive scalars in stratified turbulence
Author(s) -
Brethouwer G.,
Lindborg E.
Publication year - 2008
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2007gl032906
Subject(s) - intermittency , turbulence , scalar (mathematics) , physics , stratified flows , scalar field , turbulence kinetic energy , isotropy , dissipation , mesoscale meteorology , stratified flow , stratification (seeds) , mechanics , classical mechanics , meteorology , geometry , mathematics , optics , thermodynamics , seed dormancy , botany , dormancy , biology , germination
Statistics of a passive scalar (or tracer) with a horizontal mean gradient in randomly forced and strongly stratified turbulence are investigated by numerical simulations. We observe that horizontal isotropy of the passive scalar spectrum is satisfied in the inertial range. The spectrum has the form E θ ( k h ) = C θ ɛ θ ɛ K −1/3 k h −5/3 , where ɛ θ , ɛ K are the dissipation of scalar variance and kinetic energy respectively, and C θ ≃ 0.5 is a constant. This spectrum is consistent with atmospheric measurements in the mesoscale range with wavelengths 1–500 km. We also calculate the fourth‐order passive scalar structure function and show that intermittency effects are present in stratified turbulence.