K-distribution

About: K-distribution is a research topic. Over the lifetime, 1281 publications have been published within this topic receiving 51774 citations.

Amplitude Statistics of Weather Clutter Observed by L-band Radar

Abstract: We observed weather clutter from rain clouds using an L-band long-range air-route surveillance radar (ARSR) having a frequency 1.3 GHz, a beamwidth 1.2°, and a pulsewidth 3.0 μs. To determine the weather clutter amplitude, we introduce the Akaike Information Criterion (AIC), which is more rigorous fit of the distribution to the data than the least squares method. It is discovered that the weather clutter amplitudes obey almost the Rayleigh distribution for entire data and the Weibull, log-Weibull, and K-distributions with the shape parameters of 1.73 to 2.43, 10.60, and 5.13 to 50.93, respectively, for data within the beam width of an antenna.

SCS-CN Method Revisited Using Entropy Theory

Abstract: . The SCS-CN method is one of the most popular methods for computing runoff from small watersheds (agricultural, forest, rural, and urban) for individual rainfall events. This study revisits the method using the entropy theory, which provides insights into the structure of the method and permits derivation of the probability distributions of the variables (CN = curve number, S = maximum soil moisture retention, P = precipitation, J = cumulative infiltration, I a = initial abstraction, and Q = surface runoff) inherent in the method if they are assumed random. If the variables are continuous, then the derivation of the distributions is based on the maximization of the Shannon entropy, subject to given constraints, and the derived distributions are non-parametric. If the variables are discrete, then the derivation is based on the maximization of cross entropy, subject to fractile constraints, wherein prior probability distributions are derived by Shannon entropy maximizing. The derived distributions are tested using field data. It is found that the SCS-CN method requires no information for the probability distribution of runoff associated with it, other than obeying the total probability law. Employing four statistical measures, including Akaike information criterion (AIC), Bayesian information criterion (BIC), bias (BIAS), and root mean square error (RMSE), to determine the goodness-of-fit of probability distributions to 100-CN, Q, P, S, Q/(P-I a ), and J/S, it is found that the gamma distribution, on the whole, is the preferred distribution.

Texture and statistical distribution in high resolution polarimetric SAR images

Abstract: The validity of the product model and the corresponding K distribution for high resolution images is studied. Of particular interest are the order parameter for several types of clutter and its relation to the polarization. In experimental tests, low order parameters are measured for most clutter, indicating the high resolution enhances the texture effect. Also an extension of the product model considering backscattering from multiple layers is presented, in order to explain polarimetric variation in the measured order parameters for the forest areas at L-band.