Search

The "indeterminate" quality of Oates' writing is an asset to the oral interpreter. It demands reader participation and allows the text to become real. The imagery of violence, however, presents special problems. Upon encountering violence in the writing, the reader may experience what Leon Festinger terms "cognitive dissonance." Festinger describes this situation as the result of a person's encounter with information that contradicts his experience or that he wants to avoid, creating a psychological imbalance. According to C. William Colburn, a persuasive message should offer some recommendation which, if accepted, will restore cognitive equilibrium. In much of her literature, Oates offers such recommendations or at least a moral resolution of the material. The indeterminate quality of this resolution, however, demands sensitivity and imagination on the part of the reader. (LL)

A Lagrangean-type numerical forecasting method is developed in which the computational (grid) points are advected by the wind and the necessary space derivatives (in the pressure gradient terms, for example) are computed using the values of the variables at all the computation points that at the particular moment are within a prescribed distance of the point for which the computation is done. In this way, the forecasting problem reduces to solving the ordinary differential equations of motion and thermodynamics for each computation point, instead of solving the partial differential equations in the Eulerian or classical Lagrangean way. The method has some advantages over the conventional Eulerian scheme: simplicity (there are no advection terms), lack of computational dispersion in the advection terms and therefore better simulation of atmospheric advection and deformation effects, very little inconvenience due to the spherical shape of the earth, and the possibility for a variable space resoluti...

Experimental study of the problem of the forced adjustment of the wind field to the height field with the Mintz-Arakawa two-level atmospheric general circulation model. In all but one of the experiments, the height field was assumed to be perfectly observed at 6-hr intervals, over a time period of one day or less, and from these height data the vector wind field was computed by forced dynamical adjustment. In one experiment, the temperature alone was prescribed. The winds computed in these experiments were compared with the 'control' winds of the general circulation simulation. The best agreement between the computed and the control winds was obtained when the time-differencing scheme in the governing finite-difference equations of motion had a large rate of damping of high-frequency motions. This damping rate also determined the optimum fraction and frequency of restoration of the height (or temperature) fields. With strong damping, total restoration at every time step gave the most rapid rate of wind error reduction and the smallest asymptotic limit of the wind error.

A numerical experiment is performed with the purpose of investigating the behavior of the trajectories of a very large number of constant-volume particles. Practical significance is given to this problem by the possibility of using superpressured, constant-volume balloons for routine upper air observations. The computational scheme of the experiment is described with emphasis on some aspects of trajectory computations. Thirty-day diagnostic trajectories are computed for two levels using the total velocity components, and for one level using only the nondivergent ones, and the resulting spacing of the trajectory points is discussed. Theory of the distances to the nearest among a large number of points is developed and applied for the statistical description of the results. Histograms of distances from the constant-volume particles as well as from random points in space to the nearest neighboring constant-volume particle are computed, and compared with the frequency function of those distances for ...

A method has been developed to inherently prevent the false two-grid-interval wave in height field, which is, to the author's knowledge, at present permitted as a stationary solution to the gravity-wave part of all space-centered schemes used to solve the primitive equations in numerical forecasting and simulation experiments. The proposed method preserves space- and time-centered differencing and second-order accuracy. It involves introduction of auxiliary velocity points midway between the neighboring height grid points. Velocity components at these auxiliary points are assumed to have space-averaged values at the beginning of a considered time step; acceleration contributions are evaluated and added to these initial values to obtain components at the middle or at the end of the time step. Resulting velocity components are then used for a more accurate calculation of the divergence term in the continuity equation. The procedure leads to schemes which propagate single-grid-point height perturbations to all the existing height grid points, and thus do not permit formation of a false high wave number noise in the forecast fields. For the Heun, leapfrog, and implicit time differencing schemes an analysis is performed of the effect that this procedure has on the properties of the scheme. For the Heun scheme, the procedure results in a reduction of the instability of the scheme, and in a reduction of the truncation error. For the leapfrog scheme slight instability is produced; however, values of the amplification factors, and a numerical example, indicate that this modified leapfrog scheme can still successfully be used for integration of the primitive equations. For the implicit scheme, the procedure preserves the unconditional stability of the scheme, and also reduces the truncation error. Finally, a numerical example is shown, giving a dramatic illustration of the advantages of the proposed method. DOI: 10.1111/j.2153-3490.1973.tb00629.x