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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

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

TIROS-N data for 21 October 1979 indicate a stronger jet and cyclone vortex at 250 mb in the eastern Pacific than is suggested by forecast continuity and aircraft winds. NOAA-6 data for 29 January 1980 illustrates the problem of microwave temperature retrievals that are too low when precipitation is present. A preliminary test for the latter is outlined and recommended for users of the GWE Level lib satellite data.

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Norman A. Phillips

Abstract

A study is made of the hydrostatic and quasi-geostrophic motion of two superimposed layers of homogeneous and incompressible fluids of different densities, these fluids being contained between two rigid, horizontal plates. It is found that the local time derivatives of the pressure heights in the two layers and the height of their interface can be determined from partial differential equations similar to those developed by Charney for the equivalent-barotropic model.

The possibility of using this two-layer model to represent motions of a continuously stratified, baroclinic troposphere is explored by comparing the behavior of small perturbations superimposed on a zonal current in the two-layer model with the results of the continuous baroclinic perturbation theories of Eady and Fjørtoft. The remarkable similarity of behavior of the two-layer and the continuous perturbation models, which appears from this comparison, suggests that if the initial flow patterns of the two-layer model are determined from the initial flow patterns of the troposphere in a specified manner the later flow patterns in the troposphere can be inferred from the forecast flow patterns of the two-layer model.

This hypothesis is subjected to a preliminary test by computing the instantaneous sea-level pressure tendencies and vertical motions (in the middle troposphere) at the beginning of the severe storm of 24–25 November 1950 over eastern North America. The order of magnitude of the predicted quantities and their general distribution agree in many respects with the observed pressure changes and hydrometeors, but some disagreement exists. It is suggested that a part of this disagreement may be due to the effect of large normal accelerations on the validity of the quasi-geostrophic assumption.

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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

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

Abstract

No abstract available.

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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

No abstract available.

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