Chapter 14
Remote Sensing of Soil Moisture
Simonetta Paloscia
Consiglio Nazionale delle Ricerche
Istituto di Ricerca sulle Onde Elettromagnetiche
via Panciatichi 64, 50127 Firenze
Italy
Abstract
Remote sensing methods are of fundamental importance for soil moisture monitoring both on a
global and on a regional scale. Experimental research has demonstrated that, while observations
in the visible and thermal infrared regions of the electromagnetic spectrum are able to detect
the surface moisture of bare soils, microwave sensors are the most promising tools for obtaining
quantitative estimates of this parameter. Valuable research on this subject has been performed
worldwide, mainly in USA and Europe, and the results are reviewed in this paper on the basis
of the most advanced international research.
14.1 Introduction
Water is one of the most widely spread substances on our planet and it is present basically
in all substances, including rocks. The chemical characteristics of water, which exists in all
three states (liquid, solid and gaseous), make this element very peculiar and of fundamental
importance for life on Earth. Abundance or shortage of water has always affected the existence
of plants and animals and consequently of mankind.
14.1.1 Hydrological cycle
These preliminary remarks are necessary for explaining the importance of the study of the hydrological cycle and of the laws which regulate the Soil-Plant-Atmosphere-Continuum (SPAC),
especially on a global scale, in that the understanding of the mechanisms which regulate the
distribution of water is essential for protecting water resources and promoting a rational use of
them.
The physics of water transport in SPAC is described by the general flux equation which regulates water transport in soils (F): F=K*(~1/J/~ t), where the gradient of soil water potential
~1/J is related to the hydraulic conductivity (K, in em/sec) which is not constant with soil
NATO AS! Series. Vol. ! 45
Radiation and Water in the Climate System:
Remote Measurements
Edited by Ehrhard Raschke
If;) Springer· Verlag Berlin Heidelberg 1996
Remote Sensing of Soil Moisture
Simonetta Paloscia
Consiglio Nazionale delle Ricerche
Istituto di Ricerca sulle Onde Elettromagnetiche
via Panciatichi 64, 50127 Firenze
Italy
Abstract
Remote sensing methods are of fundamental importance for soil moisture monitoring both on a
global and on a regional scale. Experimental research has demonstrated that, while observations
in the visible and thermal infrared regions of the electromagnetic spectrum are able to detect
the surface moisture of bare soils, microwave sensors are the most promising tools for obtaining
quantitative estimates of this parameter. Valuable research on this subject has been performed
worldwide, mainly in USA and Europe, and the results are reviewed in this paper on the basis
of the most advanced international research.
14.1 Introduction
Water is one of the most widely spread substances on our planet and it is present basically
in all substances, including rocks. The chemical characteristics of water, which exists in all
three states (liquid, solid and gaseous), make this element very peculiar and of fundamental
importance for life on Earth. Abundance or shortage of water has always affected the existence
of plants and animals and consequently of mankind.
14.1.1 Hydrological cycle
These preliminary remarks are necessary for explaining the importance of the study of the hydrological cycle and of the laws which regulate the Soil-Plant-Atmosphere-Continuum (SPAC),
especially on a global scale, in that the understanding of the mechanisms which regulate the
distribution of water is essential for protecting water resources and promoting a rational use of
them.
The physics of water transport in SPAC is described by the general flux equation which regulates water transport in soils (F): F=K*(~1/J/~ t), where the gradient of soil water potential
~1/J is related to the hydraulic conductivity (K, in em/sec) which is not constant with soil
NATO AS! Series. Vol. ! 45
Radiation and Water in the Climate System:
Remote Measurements
Edited by Ehrhard Raschke
If;) Springer· Verlag Berlin Heidelberg 1996