OLR (1985) 32 (9) A. Physical Oceanography 731

difference model by means of the Lanczos method. Mitt. Inst. Meeresk. Univ. Hamb., 27:1- 78.

The Lanczos method is applied to the finite differ- ence, discretized, barotropic, frictionless hydrody- namical operator to determine the resonance modes of the World Ocean resolved on a 4 ° grid. Calcu- lations show a very dense spectrum in the period interval from 65 to 8 hr. Only modes slower than 11 hr are listed and depicted. Modes with periods 12-13 hr show, in some ocean domains, strong resem- blances to the excited M2-tide. Free modes of an isolated Atlantic Ocean on the same 4 ° grid and of a North Sea on a 37 km grid are also determined.

85:4971 Tuah, Hang and R.T. Hudspeth, 1985. Finite water

depth effects on nonlinear waves. J. Wat Way Port coast. Ocean Engng, Am. Soc. civ. Engrs, 111(2): 401-416.

Obtained from a perturbation expansion method, the first-order wave solution is assumed to be a zero- mean, Gaussian process. The skewness measure and skewness kernel for the nonlinear second-order waves are always positive and increase as the water depth decreases. Effects of the angle of intersection between interacting wave trains are examined. Bandung Inst. of Tech., Bandung, Indonesia.

85:4972 Varghese, K.K., 1984. A simple digitizer for wave

analysis. Indian J. mar. Sci., 13(4):205-206.

Potentiometric technique is used for measuring the wave height at equally spaced intervals. The device enables conversion of the analog data from a paper chart into electrical signals at equal intervals. The digitized output compares well with the manually digitized data. Center for Earth Sci. Stud., Regional Centre, Cochin 682018, India.

85:4973 Yamazaki, Hidekatsu and J.B. Herbich, 1985. De-

termination of wave height spectrum by means of a joint probabmty density function. J. geophys. Res., 90(C2):3381-3390.

Spectral analysis describes the wave energy distri- bution as a function of frequency for a given wave data set. An alternative spectrum estimation by means of the joint probability density function of wave heights and periods is presented. The wave height joint probability spectra are defined as the second moment of wave height of joint probability in terms of the frequency domain. Good agreement

with fast Fourier transform and autoregressive spectra was obtained. Ocean Engrg. Prog., Texas A&M Univ., College Station, TX, USA.

A170. Wind-wave interactions

85:4974 Mitsuyasu, H., 1985. A note on the momentum

transfer from wind to waves. J. geophys. Res., 90(C2):3343-3345.

Momentum transferred from wind to water surface goes largely into water waves when wave steepness is large. For wind-generated waves, however, much of the momentum transferred from wind to waves is lost by wave breaking, and only a small amount is advected by the waves. Res. Inst. for Appl. Mech., Kyushu Univ., Kasuga, Japan.

85:4975 Papadimitrakis, Y.A., E.Y. Hsu and R.L. Street,

1984. On the structure of the velocity field over progressive mechanically-generated water waves. Y. phys. Oceanogr., 14(12):193%1948.

The mean velocity profiles have a log-linear form with a wake free-stream characteristic. The constant which characterizes these profiles decreases with increasing wind speed, due to the variation of surface roughness condition between the transition region and the fully rough regime. Wave-associated stresses with their main component at twice the fundamental wave frequency were significant; non- linear terms in the wave-induced Navier-Stokes equations associated with these stresses cannot be neglected, and linearization is not permissible. The wave-induced velocity field and the wave-perturbed turbulence depended significantly on the ratio of the wave speed to the mean free-stream wind velocity. Coll. of Mar. Stud., Univ. of Delaware, Lewes, DE 19958, USA.

85:4976 Young, I.R. and R.J. Sobey, 1985. Measurements of

the wind-wave energy flux in an opposing wind. Y. Fluid Mech., 151:427-442.

Measurements of the wave-induced pressure closely follow the predictions of potential flow theory, with the pressure in antiphase with the water surface, hence there is no appreciable air-water energy flux due to normal stresses. Vertical and horizontal wave-induced velocities deviate slightly in magni- tude from the potential flow result. The predicted rate of decay of waves in opposing winds has a