Report on balloon shelter tests

CER68-69EJP44.For National Center of Atmospheric Research.Includes bibliographical references (page 11).March 1969

Drag on a smooth flat plate with a fence

CER63EJP66.December 1963.Includes bibliographical references.Submitted to the Society of Mechanical Engineers for presentation at the Symposium on fully separated flow, Philadelphia, Pennsylvania, April 1964.A method is presented which permits the determination of the drag on a smooth flat plate when the boundary layer along it is disturbed by a two dimensional, sharp edged fence. This method depends on the knowledge of the drag coefficient of a fence immersed in a boundary layer, and on the friction along the smooth plate in the disturbed boundary layer. The drag coefficient for the fence is calculated using arguments of free streamline theory. The friction along the smooth plate is determined approximately from experimental data. The results are applied to experimental findings of Wieghardt and satisfactory agreement was found

Evaporation from small wind waves

CER68-69JRL35.June 1969.Prepared for the National Science Foundation.Includes bibliographical references.The evaporation rates from small wind-waves by forced convection in a range where the spray of water by strong wind action is not important has been studied in the laboratory. The effects of free stream velocity, wave conditions, and temperature difference between air and water (either inversion conditions or lapse conditions) on evaporation were investigated, and the results were compared with previous work. The experimental data were correlated in terms of dimensionless groups, which were based on well-known theories for exchange processes in forced convection over solid surface. The transitional phenomenon was analyzed for evaporation as the wind blew over the solid surface onto the water surface. For the lapse condition, the temperature difference was found to cause larger growth rates of the waves as well as increased evaporation rates. The stratification of air velocity above the water surface was calculated, based on the Richardson criterion. No significant change was detected based on this criterion in this study.Under NSF grant no. GK

Experimental study of turbulent boundary layer structure, An

CER64EJP-VAS37.December 1964.Includes bibliographical references.Final Report on U.S. Army Research Grant with Meteorology Department U.S. Army Electronic Research and Development Activity, Fort Huachuca, Arizona.Under U.S. Army Research Grant DA-SIG-36-039-62-G24

Micrometeorological wind tunnel facility: description and characteristics

CER63EJP-JEC9.Includes bibliographical references (pages 39).February 1963

Backwater effects of piers and abutments

Prepared by the Civil Engineering Section, Colorado State University, Fort Collins, Colo. in cooperation with the U.S. Dept. of Commerce, Bureau of Public Roads.October 1957.CER57HKL10.Bibliography: pages 299-302

Uncertainty analysis of multi-model flood forecasts

This paper demonstrates, by means of a systematic uncertainty analysis, that the use of outputs from more than one model can significantly improve conditional forecasts of discharges or water stages, provided the models are structurally different. Discharge forecasts from two models and the actual forecasted discharge are assumed to form a three-dimensional joint probability density distribution (jpdf), calibrated on long time series of data. The jpdf is decomposed into conditional probability density distributions (cpdf) by means of Bayes formula, as suggested and explored by Krzysztofowicz in a series of papers. In this paper his approach is simplified to optimize conditional forecasts for any set of two forecast models. Its application is demonstrated by means of models developed in a study of flood forecasting for station Stung Treng on the middle reach of the Mekong River in South-East Asia. Four different forecast models were used and pairwise combined: forecast with no model, with persistence model, with a regression model, and with a rainfall-runoff model. Working with cpdfs requires determination of dependency among variables, for which linear regressions are required, as was done by Krzysztofowicz. His Bayesian approach based on transforming observed probability distributions of discharges and forecasts into normal distributions is also explored. Results obtained with his method for normal prior and likelihood distributions are identical to results from direct multiple regressions. Furthermore, it is shown that in the present case forecast accuracy is only marginally improved, if Weibull distributed basic data were converted into normally distributed variables

Investigations to develop wind tunnel techniques for measuring atmospheric gaseous diffusion in model vegetative surfaces: second annual report

CER62EJP75.December 1962.Includes bibliographical references.Prepared for the U.S. Dept. of Agriculture, Agricultural Research Service, Fort Collins, Colorado.Under contract 12-14-100-4546(41)

Wind calibration of microwave cavities

CER63EJP-JEC39.September 1963.Prepared for National Bureau of Standards.Under contract no. CST-7450