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D. Lee Harris

Abstract

By photographing the movement of smoke plumes and recording the air movement at fixed points above the water in an indoor wave tank, it is shown that progressive waves in water may produce an airflow more than half a wavelength, or 14 wave amplitudes, above the water.

The significance of this finding is that it indicates that the mean wind speed should not vanish at the mean water surface as is commonly assumed, and that the vertical gradient of the horizontal wind near the surface of water covered by progressive waves should be less than the gradient near a land surface with other conditions nearly identical.

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D. LEE HARRIS

Abstract

The upward trend in reported tornadoes during the past few years has led many people to suspect that atomic explosions are responsible for the increase. Because there is no known physical reason for believing that atomic explosions should affect the tornado frequency, the records of tornadoes and atomic explosions are examined in considerable detail to find evidence which will support or contradict this popular hypothesis.

It is found that tornado reports have always been incomplete and that much of the recent upward trend in tornado frequency can be accounted for by improvements in the tornado reporting system. A comparison of the distribution of tornadoes and of debris from an atomic explosion in time and space does not support the hypothesis that atomic explosions tend to increase the tornado frequency.

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D. LEE HARRIS

Abstract

The linearized hydrodynamic equations for storm surges are solved in analytic form for a very simple model basin and an arbitrary field of wind and pressure to show that a solution can be obtained as an integral of the product of the atmospheric forcing function and an influence function whose value tends to zero with increasing time lags. In practical cases this solution can be computed as a weighted sum of the meteorological observations during a short period before the storm surge observation.

A finite difference scheme for a slightly more general basin is then developed and the solution given formally in terms of a polynomial involving both vectors and matrices. It is shown that this solution is equivalent to the analytic solution and that both are equivalent to a linear function of the meteorological measurements of wind and pressure which must be used to obtain a description of any actual forcing function for storm surges. The technique can be generalized to provide the solution for basins of almost any shape.

The difficulties and uncertainties involved in the hydrodynamic solution are discussed, and the advantages of using a statistical method to determine the solution of the problem when sufficient data are available are shown.

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D. LEE HARRIS and ALDO ANGELO

Abstract

The practical difficulties arising in the solution of the hydrodynamic equations for storm surges by numerical methods are reviewed. It is concluded that some of these can be avoided by means of a statistical approach if sufficient records of past surges are available. A statistical approach, based on dynamic principles, is presented and the recent literature of similar studies is reviewed.

A test is made of this statistical method by applying it to recorded storm surges on Lake Erie. The agreement between the surge values computed by the statistical method and the observed values is considered good. The test verified the statistical approach but did not lead to an operational prediction system, because of recent changes in the observational practices at some of the weather stations bordering Lake Erie.

One somewhat unexpected result was a finding that a prediction scheme based on the assumption of wind stress proportional to wind speed is not significantly inferior to one-based on the assumption of a quadratic wind stress law.

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D. LEE HARRIS and CHESTER P. JELESNIANSKI

Abstract

The linearized two-dimensional hydrodynamic equations are presented in a manner which displays the principal assumptions involved. Several approximations are developed for the partial derivatives, and boundary conditions in finite difference form and the associated errors are discussed. The procedure for establishing a finite difference analog of the equations of motion and boundary conditions is illustrated, and computational stability for the solution of some simple problems is illustrated by means of examples.

The physical and computational problems associated with the introduction of friction in the computational model are discussed. It is concluded that friction should be neglected in many problems but that it must be considered in others.

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D. LEE HARRIS and CHESTER P. JELESNIANSKI

Abstract

No Abstract Available.

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W. C. CONNER, R. H. KRAFT, and D. LEE HARRIS

Abstract

No Abstract Available.

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N. R. P. Harris, L. J. Carpenter, J. D. Lee, G. Vaughan, M. T. Filus, R. L. Jones, B. OuYang, J. A. Pyle, A. D. Robinson, S. J. Andrews, A. C. Lewis, J. Minaeian, A. Vaughan, J. R. Dorsey, M. W. Gallagher, M. Le Breton, R. Newton, C. J. Percival, H. M. A. Ricketts, S. J.-B. Bauguitte, G. J. Nott, A. Wellpott, M. J. Ashfold, J. Flemming, R. Butler, P. I. Palmer, P. H. Kaye, C. Stopford, C. Chemel, H. Boesch, N. Humpage, A. Vick, A. R. MacKenzie, R. Hyde, P. Angelov, E. Meneguz, and A. J. Manning

Abstract

The main field activities of the Coordinated Airborne Studies in the Tropics (CAST) campaign took place in the west Pacific during January–February 2014. The field campaign was based in Guam (13.5°N, 144.8°E), using the U.K. Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 atmospheric research aircraft, and was coordinated with the Airborne Tropical Tropopause Experiment (ATTREX) project with an unmanned Global Hawk and the Convective Transport of Active Species in the Tropics (CONTRAST) campaign with a Gulfstream V aircraft. Together, the three aircraft were able to make detailed measurements of atmospheric structure and composition from the ocean surface to 20 km. These measurements are providing new information about the processes influencing halogen and ozone levels in the tropical west Pacific, as well as the importance of trace-gas transport in convection for the upper troposphere and stratosphere. The FAAM aircraft made a total of 25 flights in the region between 1°S and 14°N and 130° and 155°E. It was used to sample at altitudes below 8 km, with much of the time spent in the marine boundary layer. It measured a range of chemical species and sampled extensively within the region of main inflow into the strong west Pacific convection. The CAST team also made ground-based measurements of a number of species (including daily ozonesondes) at the Atmospheric Radiation Measurement Program site on Manus Island, Papua New Guinea (2.1°S, 147.4°E). This article presents an overview of the CAST project, focusing on the design and operation of the west Pacific experiment. It additionally discusses some new developments in CAST, including flights of new instruments on board the Global Hawk in February–March 2015.

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