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Open AccessJournal ArticleDOI

Analysis of surface moisture variations within large‐field sites

K. R. Bell, +3 more
- 01 Aug 1980 - 
- Vol. 16, Iss: 4, pp 796-810
TLDR
In this paper, a statistical analysis was made on ground soils to define the general relationship and ranges of values of the field moisture relative to both the variance and coefficient of variation for a given test site and depth increment.
Abstract
A statistical analysis was made on ground soils to define the general relationship and ranges of values of the field moisture relative to both the variance and coefficient of variation for a given test site and depth increment. The results of the variability study show that: (1) moisture variations within any given large field area are inherent and can either be controlled nor reduced; (2) neither a single value of the standard deviation nor coefficient of variation uniquely define the variability over the complete range of mean field moisture contents examined; and (3) using an upper bound standard deviation parameter clearly defines the maximum range of anticipated moisture variability. 87 percent of all large field moisture content standard deviations were less than 3 percent while about 96 percent of all the computed values had an upper bound of sigma=4 percent for these intensively sampled fields. The limit of accuracy curves of mean soil moisture measurements for large field sites relative to the required number of samples were determined.

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Technical Memorandum 80264
(NASA-TM-80264) ANALYSIS OF SURFACE
N79-23479
MOISTURE VARIATIONS WITHIN LARGE FIEID SITES
(NASA) 39 p HC A03/NF A01
CSCL 08H
Unclas
G3/43 25917
Analysis of Surface Moisture Variations
Within Large Field Sites
K. R. Bell, B. J. Blanchard, T. J. Schmugge and
M. W. Witczak
MARCH 1979
National Aeronautics and
Space Administration
Gi Oddwd Spne F119M Cwder
Greenbelt, Maryland 20171
by
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GODDARD SPACE FLIGHT CENTER
Greenbelt, Maryland 20771
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TABLE OF CONTENTS
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LIST OF TABLES
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Table
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Summary of Test Sites
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Summary of Large Field Moisture Data: Individual Layers . . . . . . .
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Summary of Regression Equations . . . . . . . . . . . . . . . . .
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Variation of CV and Standard Deviation for Phoenix, Arizona . . . . . . 21
iv

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Effect of surface roughness on the microwave emission from soils

TL;DR: In this article, the effect of surface roughness on the brightness temperature of a moist terrain was studied through the modification of Fresnel reflection coefficient and using the radiative transfer equation.
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TL;DR: In this article, a review of the literature relevant to a variety of scaling techniques applicable to soil moisture is presented, focusing on spatial scaling with brief reference to results on temporal scaling.
References
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Spatial variability of field-measured soil-water properties

TL;DR: In this article, hydraulic conductivity was measured as a function of soil-water content at 30.5 cm depth intervals to a depth of 182.9 cm in twenty 6.5 meters square plots randomly established over a 150-hectare field.
Journal ArticleDOI

A Comparative Study of the Effects of Albedo Change on Drought in Semi-Arid Regions.

TL;DR: In this paper, the effects of changes in albedo on rainfall in semi-arid areas were studied and the mechanism by which an increase of albedos reduces the rainfall during conditions of high evaporation was considered.
Journal ArticleDOI

Remote sensing of soil moisture with microwave radiometers

TL;DR: In this article, the authors used microwave radiometry for remote sensing of soil moisture in a series of aircraft flights over an agricultural test area in the vicinity of Phoenix, Arizona, the radiometers covered the wavelength range 0.8-21 cm.
Journal ArticleDOI

Remote Sensing of Surface Soil Moisture

TL;DR: In this article, the microwave brightness temperature (emissivity) and radar backscatter of the soil have shown correlations of up to 0.9 with the moisture in the surface layer (about 5 cm thick).
Journal ArticleDOI

Comparison of 2.8‐ and 21‐cm microwave radiometer observations over soils with emission model calculations

TL;DR: An airborne experiment was conducted under NASA auspices to test the feasibility of detecting soil moisture by microwave remote sensing techniques over agricultural fields near Phoenix, Arizona at midday of April 5, 1974 and at dawn of the following day as discussed by the authors.
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