Ian S. F. Jones

Wave Dependence of Sea-Surface Wind Stress

Abstract Distribution of the wind stress over the oceans is usually estimated by using a bulk formula. It contains the squared 10-m wind speed multiplied by the drag coefficient, which has been assumed in many cases to be a weak function of the 10-m wind speed. Over land the important role of thermal stratification has been clearly recognized, but over the sea the influence of wind waves is less well documented. This paper presents evidence showing the likelihood that the influence of the wind waves can also be large. Charnock proposed an expression for the marine atmospheric boundary layer roughness parameter, z0, which depended only on the wind friction velocity, u☆ and the acceleration of gravity, g. Toba and Koga have recently proposed an alternative expression for flow over growing wind waves, which are in local equilibrium with the wind, given by a form including the wind-wave spectral peak frequency explicity. The criterion for local equilibrium of the wave field with the wind is its consistency wi...

The Steepness and Shape of Wind Waves.

Variations are found in the shape and the steepness of wind-generated surface gravity waves between very young waves, such as seen in a laboratory tank, and larger waves of various wave ages encountered at sea as the result of wind stress over larger fetches. These differences in the characteristic shape of wind waves are presented as a function of the wave age. The wave steepness is also expressed as a function of wave age, the measurement of which is consistent with the 3/2-power law connecting wave height and characteristic period, normalized by the air friction velocity.

Richardson Number Statistics in the Seasonal Thermocline

Abstract Statistics of Richardson number in the seasonal thermocline are determined for a simple model and from experiments over the continental shelf. The model consists of normally distributed and uncorrelated density gradient and shear (such as may be caused by an internal wave field) plus a mean shear. It is shown that the most probable Richardson number may be much lower than the Richardson number based on the mean density gradient and shear. The distributions of Richardson number for two experiments in the seasonal thermocline in Bass Strait, between mainland Australia and Tasmania, are determined from a probe that samples velocity and temperature differences at 1 Hz, over vertical separations of 1 m. Away from surface wave frequencies the data are shown to be adequately described by the above model In both interfaces significant shear energy occurs above the maximum Brunt-Vaisala frequency of about 0.01 Hz. Judged by the temperature inversions of scales greater than one meter that were observed wit...

The costing of carbon credits from ocean nourishment plants.

Ocean nourishment is a process for stimulating the sequestration of atmospheric carbon dioxide in the deep ocean by providing the nutrients needed to enhance the production of phytoplankton. The carbon dioxide sink thus created, can be used to generate tradeable carbon credits. The costs of sequestering carbon by the process of ocean nourishment have been estimated using as a basis, the previous experience in nitrogen fixing of Toyo Engineering Corporation. While there are uncertainties about the biological uptake efficiency, these introduce only a moderate uncertainty in our overall estimates of costs. The major determinants of the costs are the interest that must be paid on capital and the cost of the feedstock, natural gas. We have used for discussion purposes, an interest rate of 4-8% per annum and natural gas costs of US

Engineering a large sustainable world fishery

0.5-

Photosynthetic greenhouse gas mitigation by ocean nourishment

2 per GJ. The costs of carbon credits lie in the range US

Enhanced carbon dioxide uptake by the world's oceans

6.70-

Turbulence Below Wind Waves

12.40 per tonne of carbon dioxide emissions sequestered. It should be noted that we have adopted the measure of carbon avoided by non-emission, because of the complex partitioning of anthropogenic carbon between the atmosphere, land and ocean.

The Response of Wind-Wave Spectra to Changing Winds. Part I: Increasing Winds

Mankind is faced with three interconnected problems, those of rising population, the provision of adequate food and the increasing level of waste carbon dioxide in the atmosphere. The ocean plays an important role at present by annually providing c . 90 Mt of high protein food and absorbing about 1000 Mt of carbon dioxide (CO 2 ) from the atmosphere. By the year 2100 it is predicted by the United Nations (1992) that the world population will have more than doubled its 1990 level of 5.2 thousand million people and will approach 11.5 thousand million. Most of this population increase will occur in the developing countries.

Primary production in the Sulu Sea

The phytoplankton of the upper ocean remove carbon dioxide from the atmosphere by photosynthesis. Their detritus or that of their grazers falls into the deeper ocean taking carbon with it. The ocean uptake of carbon dioxide is limited by the availability of nitrogen in the upper waters over much of the global ocean. This paper examines the cost of providing nitrogen to the upper ocean from a pilot plant with a capacity to sequester 2,000,000 tonnes of carbon dioxide per year. The plant would provide reactive nitrogen at the edge of the continental shelf and monitor the enhanced phytoplankton growth by satellite. The costs compare very favourably with other strategies of carbon dioxide capture and direct placement in carbon sinks. This comes about because the capture mechanism exploits solar energy and the large surface area of the ocean. The sequestration is shown to be permanent and not dependent on the overturning time of the ocean.