Abstract
Wave-like motions within a low-level inversion capping a morning mixed layer are studied with two instrumented aircraft, one of which is equipped with a fast-response air sensing probe. Kelvin-Helmholtz waves and their different stages of development (growth, overturning and decay) are identified by means of spectral analyses of temperature and wind component records. By analysing energy conversion rate cospectra, it is found that mechanical production terms and buoyancy production terms, respectively positive and negative during growth stage, reverse signs when overturning occurs. These results and inspection of the temporal evolution of the vertical profiles of temperature suggest that the instability recurs until the initial surplus of shear is drained. Additionally, spectra computed at the top of the mixed layer are compared with those obtained within the underlying mixed layer. The results qualitatively show that the wind shear has a non-negligible effect on the entrainment of warm air through the mixed-layer top.
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Atlas, D., Metcalf, J. I., Richter, J. H., and Gossard, E. E.: 1970, ‘The Birth of “CAT” and Microscale Turbulence’, J. Atmos. Sci. 27, 903–913.
Axford, D. N.: 1971, ‘Spectral Analysis of an Aircraft Observation of Gravity Waves’, Quart. J. Roy. Meteorol. Soc. 97, 313–321.
Ball, F. K.: 1960, ‘Control of Inversion Height by Surface Heating’, Quart. J. Roy. Meteorol. Soc. 86, 983–994.
Browning, K. A., Bryant, G. W., Starr, J. R., and Axford, D. N.: 1973a, ‘Air Motion Within Kelvin-Helmholtz Billows Determined from Simultaneous Doppler Radar and Aircraft Measurements’, Quart. J. Roy. Meteorol. Soc. 99, 608–618.
Browning, K. A., Starr, J. R., and Whyman, A. J.: 1973b, ‘The Structure of an Inversion Above a Convective Boundary Layer as Observed Using a High-power Pulsed Doppler Radar’, Boundary-Layer Meteorol. 4, 91–111.
Carson, D. J.: 1973, ‘The Development of a Dry Inversion Capped Convectively Unstable Boundary Layer’, Quart. J. Roy. Meteorol. Soc. 99, 450–467.
Caughey, S. J. and Readings, C. J.: 1975, ‘An Observation of Waves and Turbulence in the Earth's Boundary Layer’, Boundary-Layer Meteorol. 9, 279–296.
Deardorff, J. W.: 1969, ‘Numerical Study of Heat Transport by Internal Gravity Waves Above Growing Unstable Interface’, Phys. Fluids Suppl. II, 184–194.
Deardorff, J. W.: 1970, ‘Preliminary Results from Numerical Integrations of the Unstable Planetary Boundary Layer’, J. Atmos. Sci. 27, 1209–1211.
Deardorff, J. W.: 1974, ‘Three Dimensional Numerical Study of Turbulence in an Entraining Mixed Layer’, Boundary-Layer Meteorol. 7, 199–226.
Delisi, D. P. and Corcos, G.: 1973, ‘A Study of Internal Waves in a Wind Tunnel’, Boundary-Layer Meteorol. 5, 121–137.
Dutton, J. A.: 1969, ‘An Energy Budget for a Layer of Stratospheric CAT’, Radio Sci. 4, 1137–1142.
Emmanuel, C. B., Bean, B. R., McAllister, L. G., and Pollard, J. R.: 1972, ‘Observations of Helmholtz Waves in the Lower Atmosphere with an Acoustic Sounder’, J. Atmos. Sci. 29, 886–892.
Gossard, E. E., Jensen, D. R., and Richter, J. H.: 1971, ‘An Analytical Study of Tropospheric Structure as Seen by High Resolution Radar’, J. Atmos. Sci. 28, 794–807.
Guillemet, B., Mascart, P., Ravaut, M., and Isaka, H.: 1977, ‘Calibrage autonome et correction d'un système aéroporté pour la mesure du vent horizontal’, submitted to J. Rech. Atmos.
Kerman, B. R.: 1974, ‘An Energy Budget for Waves and Turbulence Within an Inversion’, Boundary- Layer Meteorol. 6, 443–458.
Lenschow, D. H.: 1970, ‘Airplane Measurements of Planetary Boundary Layer Structure’, J. Appl. Meteorol. 9, 874–884.
Lester, P. F.: 1972, ‘An Energy Budget for Intermittent Turbulence in Free Atmosphere’, J. Appl. Meteorol. 11, 90–98.
Mascart, P., Guillemet, B., and Isaka, H.: 1978, ‘Ondes de gravité interfaciales marginalement instables dans la couche limite planétaire’, submitted to Boundary-Layer Meteorol.
Metcalf, J. I. and Atlas, D.: 1973, ‘Microscale Ordered Motions and Atmospheric Structure Associated with Thin Echo Layers in Stably Stratified Zones’, Boundary-Layer Meteorol. 4, 7–35.
Metcalf, J. I.: 1975, ‘Gravity Waves in a Low-Level Inversion’, J. Atmos. Sci. 32, 351–361.
Miles, J. W. and Howard, L. N.: 1964, ‘Note on Heterogeneous Shear Flow’, J. Fluid Mech. 20, 331–336.
Otnes, R. K. and Enochson, L.: 1972, Digital Time Series Analysis, John Wiley, Interscience 463 p.
Pennell, W. T. and Le Mone, M. A.: 1974, ‘An Experimental Study of Turbulence Structure in the Fair-weather Trade Wind Boundary Layer’, J. Atmos. Sci. 31, 1308–1323.
Readings, C. J., Golton, E., and Browning, K. A.: 1973, ‘Finescale Structure and Mixing within an Inversion’, Boundary-Layer Meteorol. 4, 275–287.
Stewart, R. W.: 1969, ‘Turbulence and Waves in a Stratified Atmosphere’, Radio Sci. 4, 1269–1278.
Stull, R. B.: 1976a, ‘The Energetics of Entrainment Across a Density Interface’, J. Atmos. Sci. 33, 1260–1267.
Stull, R. B.: 1976b, ‘Internal Gravity Waves Generated by Penetrative Convection’, J. Atmos. Sci. 33, 1279–1286.
Stull, R. B.: 1976c, ‘Mixed Layer Depth Model Based on Turbulent Energetics’, J. Atmos. Sci. 33, 1268–1278.
Thorpe, S. A.: 1973, ‘Turbulence in Stably Stratified Fluids: A Review of Laboratory Experiments’, Boundary-Layer Meteorol, 5, 95–119.
Townsend, A. A.: 1966, ‘Internal Waves Produced by a Convective Layer’, J. Fluid Mech. 24, 307–319.
Townsend, A. A.: 1968, ‘Excitation of Internal Waves in a Stably-stratified Atmosphere with Considerable Wind-shear’, J. Fluid Mech. 32, 145–172.
Willis, G. E. and Deardorff, J. W.: 1974, ‘A Laboratory Model of the Unstable Planetary Boundary Layer’, J. Atmos. Sci. 31, 1297–1307.
Woods, J. D.: 1968, ‘Wave-induced Shear Instability in the Summer Thermocline’, J. Fluid Mech. 32, 791–800.
Woods, J. D. and Wiley, R. L.: 1972, ‘Billow Turbulence and Ocean Microturbulence’, Deep-Sea Res. 19, 98–121.
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IOPG, 12, avenue des Landais-63001, Clermont-Ferrand Cedex.
Complexe Scientifique des Cézeaux, BP 45-63170 Aubière.
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Mascart, P., Isaka, H. & Guillemet, B. Kelvin-Helmholtz waves observed by aircraft at different stages of their life-cycle in a low-level inversion. Boundary-Layer Meteorol 15, 31–55 (1978). https://doi.org/10.1007/BF00165504
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DOI: https://doi.org/10.1007/BF00165504