摘要:

Investigations are made of turbulence in a stably stratified fluid induced by a source of energy at the bottom. The problem is relevant to mixed layers in the upper oceans and lower atmosphere. When the source of turbulence begins, a growing mixed layer of thicknessDappears in the lower portion of the fluid separated from the non-turbulent fluid above by an interfacial layer of thicknessh. The lower mixed layer has a very weak buoyancy and the large buoyancy difference across the interface is Δb. The theoretical results depend on a Richardson. number [Rcirc]i = DΔb/u21orDΔb/w2*where the turbulent velocities in the mixed layer are of orderu1orw*in the cases of mechanical and thermal agitation, respectively.

ISSN:0309-1929    

DOI:10.1080/03091927808242647

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

In a laboratory model ocean, fluid in a rotating tank of varying depth is subjected to “wind-stress”, For a certain range of the parameters, Ekman numberEand Rossby numberR, a homogeneous fluid displays steady, westward intensified flow. For the same range ofEandR, a two-layer fluid can have baroclinic instabilities. The parameter range for the various kinds of instabilities is mapped in a regime diagram. The northward transport in the western boundary current is measured as it varies with Rossby number for both homogeneous and two-layer fluid.

ISSN:0309-1929    

DOI:10.1080/03091927808242648

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Severa1 types of fronts have been observed in the surface waters of Norwegian fjords: shear fronts along river jets, tidal/wind induced river fronts, river-river fronts and wind-driven foam fronts.

ISSN:0309-1929    

DOI:10.1080/03091927808242649

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

It is shown that an irregular bottom topography acts as a catalyst for transferring vorticity from the oscillating tidal velocity field to the mean (residual) field. A small scale vorticity field is produced by the Coriolis and frictional torques over an irregular bottom topography and subsequently transferred to the mean field by (nonlinear) advection. The transfer is such as to make the energy density of the mean field largest if the length scale of the bottom topography is of the order of the amplitude of tidal displacement.

ISSN:0309-1929    

DOI:10.1080/03091927808242650

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Barotropic and baroclinic Rossby waves in a two-layer fluid on a β-plane can interact with each other, and are unstable for all values ofM=UK2/β, whereUis the velocity amplitude of the particular wave, andKis its wavenumber modulus. The direction of energy transfer depends upon the pseudo-wavenumber, here defined as the square root of the sum of the square of the wavenumber and the inverse square of the radius of deformation of the mode; if a wave loses energy, some goes to smaller pseudo-wavenumbers as well as larger pseudo-wavenumbers. This contrasts with Fjortoft's conclusion that the direction of energy transfer in a homogeneous two-dimensional fluid is to larger and smaller wavenumbers.

ISSN:0309-1929    

DOI:10.1080/03091927808242651

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

A variational principle is presented which characterises steady motions of inviscid, rotating, stratified fluids. This is used to construct nonlinear solutions corresponding to stationary cold-core and warm-core eddies above topography in a uniform stream. Numerical results are presented for the specific case of a right circular cylinder. The results show that below a critical free-stream velocity a circular, cold, anticyclonic eddy is present above the cylinder and a warm, cyclonic eddy with the same cross-sectional area is present to the right (looking downstream) of the cylinder.

ISSN:0309-1929    

DOI:10.1080/03091927808242652

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Laboratory experiments are described in which a cylindrical obstacle is moved azimuthally through a rotating cylindrical tank of fluid in which a basic azimuthal flow inversely dependent upon the tank radius is generated by means of a source-sink arrangement. A technique is described whereby the flow can be adjusted until, relative to the obstacle, it is forward near the centre of the tank and reversed near the rim, with a monotonic variation between these extremes. The sense of this shear, relative to the obstacle, can be altered so that it either opposes or coincides with the sense of the basic rotation. Both cases are investigated in the experiments. The results of both qualitative and quantitative measurements are presented, and some comparison with related theoretical work is attempted.

ISSN:0309-1929    

DOI:10.1080/03091927808242653

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

An approximation of the annual frequencies of the “European Grosswetterlagen” (GWL) by fourth degree polynomials shows that the GWL HM and S(GT) are characterized by an inverse trend during the period 1881–1973. The periodic frequency variations of the GWL are determined by a “Maximum Entropy Spectrum Analysis”. Apart from 20–30 year periods, it is found that 13–17, 12–10 and approximately 5 year periods (in addition to a 2–3 year period) are significant.

ISSN:0309-1929    

DOI:10.1080/03091927808242654

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

From previous analysis of the daily minimum, mean and maximum temperatures in Modena, Italy over more than 100 years, it has already been demonstrated that each time series may be well represented by the sum of a seasonal deterministic function and a stationary gaussian stochastic signal. The latter was found to be autocorrelated and well represented by an autoregressive, moving-average process of order 2 and 1 respectively; AR(2)-MA(l).

ISSN:0309-1929    

DOI:10.1080/03091927808242655

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

This paper, which is partly drawn from the thesis work of one of the authors, presents experimental results of remote-sensing of plumes by optical radar.

ISSN:0309-1929    

DOI:10.1080/03091927808242656

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor