Keywords : Emissivity


Passive Microwave Technique for Estimating The Brightness Temperature of Mediterranean Sea Surface

Falih A. Aziz

Iraqi National Journal of Earth Sciences, 2014, Volume 14, Issue 1, Pages 59-77

The current study is conducted to investigate the insolation parameter in measuring sea surface temperature of Libyan city of Lipda. The process was accomplished at different bands (from 0.7 to 31.4 GHz), by using a laboratory system for microwave remote sensing in which the insolation parameter was studied with regard to temperature as well as frequencies.
In the present study, the dielectric constant of several water samples from Mediterranean sea were measured at (0.7 to 31.4 GHz) bands. The amount of reflectivity was hence calculated by Fresnel's law and then the amount of emissivity was found. The "Radiation transfer model" mathematical model was adopted in the current study to calculate the brightness temperature of the seawater as a function of angles with atmospheric effect and non-atmospheric ones. The study has come out with the conclusion that the non-atmospheric effects are less than the atmospheric ones. Sea surface temperature can be used operationally to assess eddies, fronts and upwelling for marine navigation and to track biological productivity.

Effect of Water Content on Brightness Temperature and Emissivity of Soil for Passive Remote Sensing Applications

Falih A. Aziz

Iraqi National Journal of Earth Sciences, 2014, Volume 14, Issue 1, Pages 1-18

The relative complex dielectric constant (Ɛr= Ɛ1- jƐ2) of a number of sandy soil samples from the Markib seashore, in Libya has been measured
as a function of moisture content at microwave frequency in the X-band
(f=10.7 GHz, λ=2.8 cm) and L-band (f=1.4 GHz, λ=21 cm). A knowledge of the complex dielectric constant of soils is essential in the interpretation of microwave airborne radiometer data of the Earth's surface. The reflectivity and emissivity of smooth surface have been calculated in both polarizations at various nadir angles using the measured laboratory data. It has been found that the emissivity decreases at larger angles of incidence for horizontal polarization, whereas it increases at vertical polarization with increasing incidence angle
to a maximum at the Brewster angle. It has also been observed that the incidence angle, at which the Brewster angle occurs, shifts toward grazing for higher percent moisture content. The brightness temperature of dry and wet soil has been computed in both horizontal and vertical polarization mode as a function of physical temperature and dielectric constant of each soil with varying moisture content. The brightness temperature of dry and wet soil depend on dielectric constant, physical properties, polarization and the angle of incidence of microwaves. These facts are especially important and can be used as diagnostic tool for water prospecting in deserts.