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Norman A. Phillips

Abstract

Variational analysis with a geostrophic constraint is used to estimate a critical accuracy for a satellite lidar wind measuring system. This accuracy is such that the combination of satellite winds with satellite temperatures can produce analyses with an accuracy equal to that obtained from a rawinsonde network. An important assumption allowing this estimate to be made is that the satellite wind and temperature measurements are made with a spatial density equal to that of the rawinsonde network.

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NORMAN A. PHILLIPS

Abstract

A 48-hr. forecast for the entire Northern Hemisphere of a barotropic hydrostatic atmosphere is made with the “primitive equations.” Overlapping Mercator and stereographic grids are used, together with the finite-difference scheme proposed by Eliassen. Initial data corresponded to a Haurwitz-type pattern of wave number 4. The initial wind field was nondivergent and the initial geopotential field satisfied the balance equation. The computations seem to be stable and well behaved, except for two small temporary irregularities. The amplitude of the gravity-inertia waves present in the forecast geopotential field is about 1/30 that of the large-scale field. It can be shown that this is due to the neglect, in the initial data, of the quasi-geostrophically conditioned divergence field. The computational technique itself therefore does not give any unreal prominence to the “meteorological noise.” The computational characteristics and stability criterion of the Eliassen finite-difference system are investigated for a linearized version of the equations.

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Norman A. Phillips

A linear dynamical prediction model is combined with a linear analysis scheme to give a formula for the expected squared forecast error, as a function of space and time, given a knowledge of observational error covariance and spectrum of the true field. The formula is applied with a two-layer geostrophic model to estimate the maximum impact of tropospheric temperatures derived from satellite radiances over oceanic areas on the accuracy of 500 mb forecasts over North America. The results show a positive impact if the observations are analyzed by an unrealistically efficient optimum interpolation method, but they show a negative impact at all but the smallest satellite error values if the observations are analyzed by a method that ignores observational errors. Eight conclusions are reached concerning routine numerical forecasts and the First GARP Global Experiment.

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Norman A. Phillips

Abstract

The Baer-Tribbia nonlinear modal initialization method implies that large-scale meteorological analyses should focus on analysis of slow mode fields. An idealized multi-variate optimum interpolation analysis is shown to produce grid point results that contain only slow modes. Variational analysis with a slow mode constraint is therefore unnecessary.

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Norman A. Phillips

Abstract

The flux of energy due to the pressure force acting across the boundary of a subsiding mass of cold air is investigated. It is shown that for mean values of the subsiding motion of the order of −1 cm sec−1 or larger, energy is transferred from the cold air to the surrounding atmosphere. A method is developed whereby this flux across a portion of a frontal surface can be calculated from a three-dimensional frontal analysis, and this technique is then applied to a specific example. The importance of the addition of this energy to the current flowing around the cold air is discussed, and it is suggested that at least a portion of the energy for the indirect circulations which are often observed downstream is supplied by the direct circulation involving the subsiding cold air mass.

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Norman A. Phillips

Abstract

No abstract available.

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Norman A. Phillips

Abstract

An experimental colocation and statistical regression scheme is used to verify the hypothesis that large consistent mean errors in the cloudy oceanic satellite temperature retrievals north of 30°N from TIROS-N are due to a continental bias in the statistical colocation base. Sea surface water temperature is a useful predictor for these conditions. Significant improvement in these retrievals is possible. However, much of this improvement requires the presence in the colocation base of the, mid-ocean radiosondes from the ocean weather ships.

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Norman A. Phillips

Inertia circle motion is a familiar concept demonstrating the behavior of a horizontally moving particle on the rotating earth in response to the Coriolis force. Three dynamical principles valid in nonrotating space are used to explain the principal properties of this motion without the need for solving differential equations. The motion is an oscillation about a central latitude selected by the particle's angular momentum, in which the restoring force is set by the relative magnitudes of the poleward attraction of gravity and the equatorward attraction of the centrifugal force as the particle oscillates about the central latitude.

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Norman A. Phillips

The many activities of Carl-Gustaf Rossby are described, beginning with his early adventures at sea, and presented in the context of the meteorological world of his time. His scientific ideas and papers are not discussed except for an important aspect of his typical approach to analysis of atmospheric and oceanic motion. His success in fostering interaction between different people and institutions is emphasized.

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Norman A. Phillips

Abstract

No abstract available.

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