208 A. Physical Oceanography OLR (1986) 33 (3)

during the storm surge was calculated. It is con- cluded that water exchange between the North and Baltic seas should be included in storm surge studies. Inst. of Meteorol. and Water Mgmt., Gdynia, Poland.

86:1433 Chilicka, Zofia and Zygmunt Kowalik, 1984. Influ-

ence of water exchange between the Baltic Sea and the North Sea on storm surges in the Baltic. Oceanologia, Warsz., 19:5-23.

The principal result of the paper is the conclusion that the omission of the influence of water exchange in the central Baltic, the Gulf of Riga, the Gulf of Finland and the Gulf of Bothnia, in a time interval longer than 24 hours leads to considerable errors. In the Belt Straits and in the southern Baltic the influence of water exchange is considerable even during the first 12 hours of a storm. Inst. of Meteorol. and Water Mgmt., Gdynia, Poland.

86:1434 Choi, B.H., 1985. Computation of the typhoon surges

of Jnly-Angust 1978 in the East China Sea. J. oceanoL Soc. Korea, 20(1):1-11. (In Korean, English abstract.) Dept. of Civil Engrg., Sungkyunkwan Univ., Suwon 170, Korea.

86:1435 Dobson, Fred (comment), S. Tang and O.H.

Shemdin (reply), 1985. Comment on 'Measure- ment of high-frequency waves using a wave follower.' J. geophys. Res, 90(C5):9203-9204. Bedford Inst. of Oceanogr., Dartmouth, NS, Canada.

86:1436 Hameed, T.S.S. and M. Baba, 1985. Wave height

distribution in shallow water. Ocean Engng, 12(4):309-319.

The probability distribution of shallow water wave heights is examined and tested with the theoretical distributions of (a) Rayleigh, (b) Weibull, (c) Gluhovski, (d) Ibrageemov and (e) Goda. The best fit is shown by the Gluhovski probability density function with a correlation coefficient greater than 0.8. The functions of Weibull, Ibrageemov and Goda fit only half the tested cases. The role of wave steepness in the wave height distribution is found to be negligible. Centre for Earth Sci. Studies, Regional Centre, Cochin-18, India.

86:1437 Huang, N.E., C.-C. Tung and R.J. Lai, 1985. A note

on the statistics of threshold crossing for a

nonlinear wave field. Ocean Engng, 12(4):363- 368.

Based on the non-Gaussian joint elevation and slope density function developed by Huang et al. (1984), the expected number of threshold crossing at an arbitrary level for a nonlinear wave field is derived. Distribution of the expected threshold crossing per unit time as a function of the crossing level is skewed with respect to the mean water level, causing the mean zero crossing per unit time to deviate from the expected frequency of the wave field. Lab. for Oceans, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.

86:1438 Hunter, J.K., 1985. A ray method for slowly modu-

lated nonlinear waves. SlAM J. appL Math, 45(5):735-749.

An asymptotic theory for weakly nonlinear high- frequency waves is extended to include weak dispersion and dissipation, and used to obtain slowly modulated solutions of the KdV equation. A KdV equation for shallow water waves and a Burgers' equation for sound waves in a relaxing gas, in several space dimensions, are derived. Dept. of Math., Colorado State Univ., Fort Collins, CO 80523, USA.

86:1439 Liu, P.L.-F. and T.-K. Tsay, 1985. Numerical

prediction of wave transformation. J. WatWay Port coast. Ocean Die., Am. Soe. cir. Engrs, 111 (5): 843-855.

A numerical model based on the parabolic ap- proximation method is developed for monochro- matic linear waves and considers refraction, dif- fraction, and energy dissipation caused by the bottom turbulent boundary layer. A numerical algorithm treats digitized bathymetry data. Sch. of Cir. and Environ. Engrg., Cornell Univ., Ithaca, NY, USA.

86:1440 Miles, John and Rick Salmon, 1985. Weakly disper-

sive nonlinear gravity waves. J. Fluid Mech, 157:519-531.

The equations for gravity waves on the free surface of a laterally unbounded inviscid fluid of uniform density and variable depth under the action of an external pressure are derived through Hamilton's principle on the assumption that the fluid moves in vertical columns. Potential vorticity vanishes in any flow that originates from rest; this leads to a canonical formulation in which the evolution equa- tions are equivalent, for uniform depth, to Whitham's (1967) generalization of the Boussinesq