Showing papers on "Weather radar published in 1971"

Characterization of ceramics

Abstract: This book reviews the principles of Doppler radar and emphasizes the quantitative measurement of meteorological parameters. It illustrates the relation of Doppler radar data and images to atmospheric phenomena such as tornadoes, microbursts, waves, turbulence, density currents, hurricanes, and lightning. Geared toward upper-level undergraduates and graduate students, this text was written by two scientists at the National Severe Storms Laboratory in Norman, Oklahoma, a division of the National Oceanic and Atmospheric Administration. Topics include electromagnetic waves and propagation, weather signals and their Doppler spectra, weather signal processing, measurements of precipitation and turbulence, and observations of winds and storms as well as fair weather. Radar images and photographs of weather phenomena highlight the text.

The effect of variable target reflectivity on weather radar measurements

Abstract: Weather radar signals fluctuate because of relative motions among the scatterers; these fluctuations must be accounted for in quantitative reflectivity measurements. The standard theory of weather signal fluctuations assumes targets of fixed reflectivity. In actual measurements, signals from a volume in space and over a short period of time are combined to yield an overall reflectivity measurement. Within this measurement region the reflectivity may not be constant, in which case the standard-fluctuation theory will not strictly apply. It is shown that the theory can readily be extended to include reflectivity variations. Models of the reflectivity structure are introduced to assess the effects of these variations on reflectivity measurements. If the measurement is made by averaging the signal and applying the standard theory, it will tend to underestimate the actual target reflectivity whenever variations are present except for the special case of a radar with a quadratic receiver response. If reflectivity is measured by selecting the maximum intensity level from a sample of size N and applying standard theory, it will tend to overestimate the actual target reflectivity when variations are present. The variance of the measurement is increased by reflectivity variations, whether averaging or peak-detecting is employed. These effects are expected to introduce only small errors (less than 5 dB) in all but extreme cases of reflectivity variations, but such errors can be significant in applications of radar to problems in hydrology or communications, where high accuracy of measurements is required.

A technique for assessing probable distributions of tropical precipitation echo lengths for X-band radar from Nimbus 3 HRIR data

Abstract: Statistical model for simulating radar echoes from tropical precipitation for ocean surface region using Nimbus 3 satellite infrared data

High-power radar for meteorological stuides in clear air

Abstract: A very high-sensitivity S band radar capable of detecting targets with radar cross-section of 5 × 10−10 m2 of reflectivities of 2 × 10−15 m−1 at a range of 10km has recently been brought into operation for meteorological studies of the clear atmosphere. The paper outlines the constraints set by the meterological requirements, and describes the radar which has been assembled to meet them. Examples are presented of clear-air echoes obtained both from extensive horizontal layers at hieghts up to 3 km, and also from high-altitude clear-air turbulence.

Simultaneous multiple wavelength laser radar measurements of the lower atmosphere

Abstract: Lower atmospheric multiple wavelength laser radar data compared to clear atmosphere model and radiosonde measurements, discussing mixing layer location

Three dimensional model of precipitation echoes for X-band radar data collected during BOMEX

Abstract: Three dimensional statistical model for deriving precipitation estimate from X band radar echoes

Radar, aircraft, and meteorological observations of shear induced clear air turbulence

Abstract: High power 10 cm radar as CAT detector, comparing with radar and aircraft data coincident in space and time

The upwind/downwind dependence of the doppler spectra of radar sea echo

Abstract: A detailed investigation of the differences between the upwind and downwind Doppler spectra of the radar sea echo has been made, utilizing P- , L- , and C -band data obtained with the Naval Research Laboratory's Four-Frequency Radar System. The results indicate that while the Doppler bandwidth is nearly independent of wind direction, the differential Doppler looking upwind is nearly twice that for the downwind case.