Maritime Front Research Articles

The Maritime Front of the Rı́o de la Plata as an instrument for binational fisheries management

The purpose of this paper is to outline the wealth of experience obtained by Argentine and Uruguay through the reciprocal cooperation framework provided by the Treaty of the Rı́o de la Plata and its Maritime Front. This agreement, signed by both countries in November 1973, provided for the establishment of a Common Fishing Zone and an international governmental agency, the Comisión Técnica Mixta (Binational Technical Commission), whose main functions include achieving the rational exploitation of the marine resources in those waters. 2 2 República Argentina – República Oriental del Uruguay. 1973. “Tratado del Rı́o de la Plata y su Frente Marı́timo”. Signed on the 19th November. The Treaty entered into force the 12th February 1974. On the Binational Technical Commission see Ref [1]: Also see Ref [2]: It is important to keep in mind that the Treaty actually deals with two distinct geographical spaces: the Maritime Front and the Rı́o de la Plata, providing a specific legal framework for each of them. This includes the establishment of two intergovernmental organizations: the Comisión Técnica Mixta del Frente Marı́timo (Maritime Front Binational Technical Commission) and the Comisión Administradora del Rı́o de la Plata (Rı́o de la Plata Managing Commission). This latter body has basically the same tasks and functions than the Binational Technical Commission. Both Commissions were established in 1976. It has been considered advisable to retain in the text the name Rı́o de la Plata in Spanish.

Surface Dynamics of Observed Maritime Fronts

The problem of establishing the important mechanisms and processes in surface fronts is examined. It is shown that boundary layer processes may modify the details of frontal dynamics near the surface and that at the same time fronts may alter boundary layer solutions. A similarity model that assumes a horizontally homogeneous steady-state planetary boundary layer is used to test the effects of baroclinity and stratification on the ageostrophic vorticity. Model response to baroclinity and stratification is tested. A boundary layer positive feedback mechanism that stems from the variation in stratification and thermal advection across a front and favors the creation of stronger temperature gradients in cold fronts is proposed. A compatible model that includes the effects of horizontal inhomogeneity is derived and used in conjunction with scatterometer data to observe the behavior of five surface fronts. Observations are compared to results of numerical models by several authors and it is concluded that a few scenarios for the evolution of surface fronts exist. Surface friction is important in frontal processes through its role in determining the dissipation and the ageostrophic terms in the vorticity and divergence equations. The former normally acts to weaken a front while the latter normally acts to strengthen it. The magnitude and importance of these terms vary considerably at different stages and with stratification, thermal advection, and the deformation and shear forcing. Except for one case of an explosive storm where wave activity is suspected, the convergence coincides with the cyclonic vorticity in frontal zones. The inclusion of the inertial terms representing the deformation in the Ekman solution tends to concentrate gradients by increasing frontogenesis in vorticity at or slightly ahead of the front while diminishing it elsewhere. The nonlinear terms in the divergence equation are frontogenetic for all fronts. Their relative importance varies considerably for different fronts, however.

FRONTAL PERTURBATION OF A TROPOSPHERIG SCATTER PATH

A 2-year study of 500 Mc/s radio transmissions over an 85-mile path near Ottawa has shown that the signal fading rate rises well above the diurnal maximum when the transmission path is perturbed by a weather front. The fading rate reaches a maximum when the upper boundary of the frontal zone is 3000 feet above the center of the radio path, and the fading rate remains high as long as any part of the frontal zone is between the surface and 3000 feet. A similar relationship between frontal position and signal fading rate is found for Arctic, Maritime, or Polar fronts in the Ottawa area, but the Arctic fronts provide the clearest definition. There is some indication that high fading rate also may be associated with horizontal layers of contrasting humidity at low levels in the troposphere.

An operational frontal contour‐analysis model

AbstractA three‐front model is proposed as a practical solution to analysis problems associated with both surface fronts and the baroclinic currents of the upper westerlies. They are called the ‘polar front,’ the ‘maritime front,’ and the ‘arctic front.’A front is defined as a three‐dimensional baroclinic zone, having a first‐order discontinuity in the temperature and wind fields, and being reasonably continuous in space and time. Frontal contour analysis is found to be operationally practicable and desirable.