Distributions of Radar Echoes Over the United States

Distributions of Radar Echoes Over the United States

Author: D. D. Grantham

Publisher:

Published: 1967

Total Pages: 392

ISBN-13:

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The frequency and probability of radar echoes of convective clouds over the United States are presented. Analysis of three years of observations from a 31-station WSR-57 weather radar network indicates that at all altitudes, radar echo probabilities are greatest over Florida and the Gulf coast, generally decreasing northward over the United States. Also, largest probabilities for most layers and locations occur in summer. Echoes have been reported up to at least 70 kft in May, June, and July, and up to 60 kft in winter. Diurnal variations reveal greatest probabilities between 1600 and 2100 1st in all regions. Largest mean monthly 3-hour values are 85 percent, and the maximum mean daily range is roughly 65 percent in the southeast during the summer months. The probability of an echo-free horizontal view near the earth's surface for a 100-mile range is also presented. Tabulations of echo-free sectors, as percent of the 360-degree radar scope, show that the probability of obstructions to a horizontal view increases generally from northwest to southwest during all seasons. The probability of having no echoes is greater in winter than in summer except along the Pacific coastal region. Diurnal variability is larger in July than in January. (Author)


Distributions of Radar Echoes Over the United States

Distributions of Radar Echoes Over the United States

Author: D. D. Grantham

Publisher:

Published: 1967

Total Pages: 388

ISBN-13:

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The frequency and probability of radar echoes of convective clouds over the United States are presented. Analysis of three years of observations from a 31-station WSR-57 weather radar network indicates that at all altitudes, radar echo probabilities are greatest over Florida and the Gulf coast, generally decreasing northward over the United States. Also, largest probabilities for most layers and locations occur in summer. Echoes have been reported up to at least 70 kft in May, June, and July, and up to 60 kft in winter. Diurnal variations reveal greatest probabilities between 1600 and 2100 LST in all regions. Largest mean monthly 3-hour values are 85 percent, and the maximum mean daily range is roughly 65 percent in the southeast during the summer months. The probability of an echo-free horizontal view near the earth's surface for a 100-mile range is also presented. Tabulations of echo-free sectors, as percent of the 360-degree radar scope, show that the probability of obstructions to a horizontal view increases generally from northwest to southwest during all seasons. The probability of having no echoes is greater in winter than in summer except along the Pacific coastal region. Diurnal variability is larger in July than in January. (Author)


Interpretation and Application of Nimbus High-resolution Infrared Radiometer Data for Southeast Asia

Interpretation and Application of Nimbus High-resolution Infrared Radiometer Data for Southeast Asia

Author: Rupert S. Hawkins

Publisher:

Published: 1969

Total Pages: 92

ISBN-13:

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Comparative studies of Nimbus I and Nimbus II HRIR pictures over Southeast Asia with supporting surface and radar observations disclose that bright areas (cold temperatures) in HRIR pictures correspond to areas of precipitation revealed by radar and substantially agree with a rain index based on 12-hr rainfall reports from six stations. The Nimbus infrared pictures are significantly different from satellite daytime video pictures, however, and consequently require different interpretation.