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Robert G. Fleagle

Abstract

The local twelve-hour change of temperature lapse rate from 5,000 to 10,000 feet is computed in 50 cases as a function of horizontal velocity divergence and vertical variation of horizontal temperature advection, and the result compared with the observed change of lapse rate. The divergence is measured from charts of horizontal velocity components; the vertical variation of horizontal temperature advection is measured by the rate of flow across the isotherms at two different levels and, as an alternate method, by the hodograph. The standard errors of estimate for these two methods are, respectively, 2.2 and 4.4 C km−1. The reliability of the measurements of divergence is studied by comparing the measured values with values computed from the difference between observed change of lapse rate and vertical variation of advection. The correlation coefficient relating these two methods is + 0.60 when advection is measured on constant level charts and + 0.40 when advection is measured by the hodograph.

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Robert G. Fleagle

Abstract

Theoretical considerations suggest that the temperature distribution within a meter of a cold surface may be partially stratified as a result of radiative and turbulent processes. Even though stratification would be of crucial importance in certain boundary-layer processes, it probably would be undetectable by conventional thermometry. Observations using direct refractive thermometry have been used to determine with great accuracy the temperature distribution above a cold water surface. These observations reveal a persistent temperature anomaly about 10 centimeters above the surface, which is consistent with theory.

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Robert G. Fleagle

Abstract

The contribution to density change made by local compression or expansion, advection, and vertical motion, and by horizontal mass divergence or convergence is determined for 132 cases chosen during a period of anticyclogenesis above a polar anticyclone and during two periods of cyclogenesis. The density change in the layer two or three kilometers in thickness just above the tropopause is shown to contribute most to pressure change at the ground. This density change may be considered to be the result either of advection in the lower stratosphere or of the excess of horizontal mass divergence over vertical mass divergence.

Advection in the lower stratosphere is found to be closely related to local pressure change and to vertical motion in the upper and middle troposphere: downward motion accompanies rising pressure and advection of denser air and upward motion accompanies falling pressure and advection of lighter air.

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Robert G. Fleagle

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Robert G. Fleagle

Abstract

An equation is derived from the linearized equations of planetary aerodynamics which expresses the vertical component of velocity as a function of baroclinity, static stability, geostrophic vorticity, and geostrophic wind speed toward the north. The properties of this equation are compared with those of other equations and it is concluded that the linear equation provides an insight into the mechanism of large-scale vertical motion and that it is simple enough for easy application to real data. Calculations of vertical velocity using the linear theory are compared with calculations using the adiabatic method, with calculations using two nonlinear methods, and with cloudiness and precipitations. The linear theory yields results which are relatively insensitive to errors in observation and analysis, and which compare favorably with results calculated from other methods. On the other hand, it is not notably more accurate than are other methods; all introduce errors which are comparable to the calculated values.

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Robert G. Fleagle

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Robert G. Fleagle

Abstract

The fields of temperature, pressure, and three-dimensional motion are shown on horizontal charts and vertical cross sections for a period of anticyclogenesis above a polar anticyclone and for periods of cyclogenesis in Colorado and on the east coast of the United States. Prominent features of the charts are indicated, and certain outstanding relationships connecting temperature advection, vertical component of velocity, and local pressure change are discussed.

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Robert G. Fleagle

The National Oceanic and Atmospheric Administration (NOAA) is not adequately equipped to meet the needs of the future for research, services, and information relating to the natural environment. A restructuring of NOAA is called for, which would fill gaps in its program, assure strengthened capabilities for global observations, and help the agency to balance its multiple missions, and to order priorities in a manner consistent with the public interest. To implement those changes, a new legislative charter is needed defining new agency objectives and establishing the agency independent of the US Department of Commerce (DOC).

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Robert G. Fleagle

The need for reliable determination of the temperature of the air very near the ground and the difficulties inherent in measurement of this quantity by the ordinary indirect methods are pointed out. It is suggested that the dependence of the speed of light on air density provides a convenient method for the determination of the temperature near the ground by direct measurement of the lapse rate, and evidence is given from other papers to show that this is feasible where the vertical gradient of humidity is not great. The relationship between apparent elevation and lapse rates of temperature and vapor pressure is derived, and the relationship is illustrated by the results of computations.

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Robert G. Fleagle

Abstract

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