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Jerome Spar

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Jerome Spar

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The stability characteristics of waves in a thermotropic atmosphere are computed for several velocity profiles. It is shown that the critical wavelength for any wind shear varies considerably with the shape of the velocity profile.

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Jerome Spar

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Jerome Spar

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A quantitative theory is derived showing the relation between temperature and surface pressure oscillations. By extension of methods used by Jeffreys and Bartels, a solution is obtained for the linearized hydro-dynamic equations in terms of spherical surface harmonic functions. The solution gives the surface pressure variation as a function of an integral containing the temperature variation throughout the atmosphere. The theory is applied to the problem of evaluating the amplitude of the annual surface pressure oscillation over the whole sphere. The temperature integral is computed from mean data for January and July and subjected to spherical harmonic analysis. The mean semi-annual surface pressure change is then evaluated from the coefficients of the harmonic series for the temperature integral and compared with observations.

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JEROME SPAR

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The global response of the atmosphere, as simulated by the Mintz-Arakawa, two-level, general circulation model, to a persistent anomalous pool of warm sea-surface temperatures (SST) in the extratropical Pacific Ocean is examined in this descriptive study in terms of the meridional pole-to-pole profile of the zonally averaged 600-mb surface for periods up to 90 days. Following an initial hydrostatic inflation of the isobaric surface in the latitude of the warm pool, effects spread poleward within the hemisphere, then begin to appear after about 2–3 weeks in high latitudes of the opposite hemisphere, but with little or no response in the Tropics. The same sea temperature anomaly field generates a stronger response in winter than in summer and a very different reaction when located in the Southern Hemisphere than when in the Northern Hemisphere. After a month of thermal forcing, the response to an SST anomaly is at least as large in the opposite hemisphere as in the hemisphere of the anomaly. A winter hemisphere responds more rapidly to an SST anomaly in the opposite hemisphere than does a summer hemisphere. Vacillation between low and high meridional wave number patterns is observed in the computed reaction to the warm pool.

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Jerome Spar

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Jerome Spar

The mean diurnal pressure curve was computed separately for days with large and for days with small ranges of temperature. Harmonic analysis of the two curves shows that the amplitude of the semidiurnal, as well as the diurnal, component is larger on days with large range of temperature. The semidiurnal maxima occur earlier on days with small temperature range.

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JEROME SPAR

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The Mintz-Arakawa two-level general circulation model has been used in a series of experiments to compute the response of the atmosphere to certain persistent sea-surface temperature anomalies and to changes in the position of the continental Northern Hemisphere snow line over periods up to 90 days. Results are shown in terms of differences between anomaly and control histories as revealed by global, 30-day mean sea-level pressure maps and time series of three regional indices of synoptic activity. The experiments show significant interhemispheric effects after about 1 mo, phase shifts of 1–2 weeks in major cyclone developments, stronger reactions to sea-temperature anomalies in winter than in summer, and marked influence of the snow line on the winter monsoonal pressure difference between the continents and the North Atlantic Ocean.

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JEROME SPAR

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The theory and computation of integrated water vapor transport vectors are described and it is shown how the synoptic analysis of these vectors may be used for quantitative precipitation forecasting. An example of the vector field and the precipitation forecast is given. Although the prognostic formula does not give correct point values of the precipitation, reasonably good agreement is found between the distributions of forecast and observed precipitation. The technique is probably too laborious for daily forecasting routine but may be useful in the evaluation of rainmaking experiments.

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Jerome Spar

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No Abstract Available

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