On momentum flux and velocity spectra over waves

Data from a research tower in Lake Ontario are used to study the validity of Monin--Obukhov scaling in the marine atmospheric boundary layer under various wave conditions. It is found that over pure wind seas, the velocity spectra and cospectra follow established universal scaling laws. However, in the presence of swells outrunning weak winds, velocity spectra and cospectra no longer satisfy universal spectral shapes. Here, Monin–Obukhov similarity theory, and the classical logarithmic boundary layers, are no longer valid. It is further shown that, in the presence of such swells, the momentum flux can be significantly modified in comparison to pure wind sea values. The implications of these findings for bulk flux estimations and on the inertial dissipation method for calculating fluxes are discussed.

[1]  J. Capon.  High-resolution frequency-wavenumber spectrum analysis , 1969 .

[2]  L. Hasse,et al.  Sea surface wind stress and drag coefficients: The hexos results , 1992 .

[3]  R. W. Stewart,et al.  Spectra and cospectra of turbulence over water , 1970 .

[4]  W. Large,et al.  Open Ocean Momentum Flux Measurements in Moderate to Strong Winds , 1981 .

[5]  U. Högström.  Review of some basic characteristics of the atmospheric surface layer , 1996 .

[6]  Paul B. MacCready,et al.  Response Characteristics and Meteorological Utilization of Propeller and Vane Wind Sensors , 1964 .

[7]  Stuart D. Smith.  Wind Stress and Heat Flux over the Ocean in Gale Force Winds , 1980 .

[8]  R. W. Stewart.  The wave drag of wind over water , 1961, Journal of Fluid Mechanics.

[9]  G. Geernaert,et al.  Directional attributes of the ocean surface wind stress vector , 1993 .

[10]  Christopher W. Fairall,et al.  Similarity Relationships in the Marine Atmospheric Surface Layer for Terms in the TKE and Scalar Variance Budgets , 1998 .

[11]  M. Donelan,et al.  Directional spectra of wind-generated ocean waves , 1985, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[12]  A. Obukhov,et al.  Turbulence in an atmosphere with a non-uniform temperature , 1971 .

[13]  Jerome A. Smith,et al.  Removing wave effects from the wind stress vector , 1998 .

[14]  H. Charnock.  Wind stress on a water surface , 1955 .

[15]  A. S. Monin,et al.  BASIC LAWS OF TURBULENT MIXING IN THE GROUND LAYER OF THE ATMOSPHERE (OSNOVNE ZAKONOMERNOSTI TURBULENTNOGO PEREMESHIVANIYA V PRIZEMNOM SLOE ATMOSFERY) , 1959 .

[16]  Stuart D. Smith,et al.  Spectra of humidity, temperature, and wind over the sea at Sable Island, Nova Scotia , 1984 .

[17]  M. Donelan,et al.  Miniature drag sphere velocity probe. , 1978, The Review of scientific instruments.

[18]  B. Hicks,et al.  Flux‐gradient relationships in the constant flux layer , 1970 .

[19]  B. Hicks.  Propeller anemometers as sensors of atmospheric turbulence , 1972 .

[20]  Karl F. Rieder.  ANALYSIS OF SEA-SURFACE DRAG PARAMETERIZATIONS IN OPEN OCEAN CONDITIONS , 1997 .

[21]  Hans Bergström,et al.  A case study of air‐sea interaction during swell conditions , 1999 .

[22]  M. Donelan,et al.  On the Dependence of Sea Surface Roughness on Wave Development , 1993 .

[23]  E. F. Bradley,et al.  Flux-Profile Relationships in the Atmospheric Surface Layer , 1971 .

[24]  A. Yaglom,et al.  Comments on wind and temperature flux-profile relationships , 1977 .

[25]  Albert J. Williams,et al.  Estimates of Kinetic Energy Dissipation under Breaking Waves , 1996 .

[26]  C. Mastenbroek,et al.  Impact of waves on air-sea exchange of sensible heat and momentum , 1996 .

[27]  G. Geernaert,et al.  Air-sea fluxes: 25 years of progress , 1996 .

[28]  P. K. Taylor,et al.  Wind stress measurements from the open ocean , 1996 .

[29]  Peter A. E. M. Janssen,et al.  Wave-induced stress and the drag of air flow over sea waves , 1989 .

[30]  R. Weller,et al.  Observed directional characteristics of the wind, wind stress, and surface waves on the open ocean , 1994 .

[31]  Michael Tjernström,et al.  The Near-Neutral Marine Atmospheric Boundary Layer with No Surface Shearing Stress: A Case Study , 1994 .

[32]  J. Kaimal,et al.  Spectral Characteristics of Surface-Layer Turbulence , 1972 .

[33]  M. Donelan,et al.  Apparatus for Atmospheric Surface Layer Measurements over Waves , 1999 .

[34]  M. Donelan.  Air-sea interactions , 1990 .

[35]  Robert J. Anderson,et al.  Measuring the relationship between wind stress and sea state in the open ocean in the presence of swell , 1994 .

[36]  G. Geernaert,et al.  Variation of the drag coefficient and its dependence on sea state , 1986 .

[37]  M. Donelan,et al.  Evidence for the Effects of Swell and Unsteady Winds on Marine Wind Stress , 1999 .

[38]  Christopher W. Fairall,et al.  A study of the inertial‐dissipation method for computing air‐sea fluxes , 1991 .

[39]  Mark A. Donelan,et al.  The Air–Sea Momentum Flux in Conditions of Wind Sea and Swell , 1997 .

[40]  W. J. Moore,et al.  Measuring the relationship between income and NHEs , 1992, Health care financing review.