Modeling and observation of polarimetric SAR response to dry snow
Snow water equivalence (SWE) is one of the most important parameters for hydrological investigations. In this study, the authors show (1) a method of using stereological technique to determine snow parameters for microwave modeling, (2) comparison of NASA/JPL AIRSAR measurements with the model predictions and the numerical simulations of the relationships between the backscattering signals and snow physical parameters. The results indicate that the relationship between the co-polarization signals and snow water equivalence can be either positive or negative depending on the snow physical parameters, ground surface parameters and incidence angle. At C-band, the major scattering source is the interface between the snow and ground. X-band or higher frequency SAR sensor is needed for snow depth measurement. >
A new estimator for a four-element plane array is introduced in order to get acoustic-passive direction estimation of targets.We concern much about the performance of the estimator under a two-target situation.In this paper,the two targets concerned are of the same type of acoustic source.Under different signal to interfere ratios,we propose the change of the precision of the direction estimation as the angle between the two targets changes.Our study was done under the real time Warfield situation,and may help the design of small acoustic-passive direction estimation arrays.