2008 NOV 3 - (VerticalNews.com) -- According to a study from the United States, "The quality of polarimetric radar rainfall estimation is investigated for a broad range of distances from the polarimetric prototype of the Weather Surveillance Radar-1988 Doppler (WSR-88D). The results of polarimetric echo classification have been integrated into the study to investigate the performance of radar rainfall estimation contingent on hydrometeor type. ...read more

  2008 NOV 3 - (VerticalNews.com) -- "Markov chains are widely used tools for modeling daily precipitation occurrence. Given the assumption that the Markov chain model is the right model for daily precipitation occurrence, the choice of Markov model order was examined on a monthly basis for 831 stations in the contiguous United States using long-term data," researchers in the United States report.

  "The model order was first identified using the Bayesian information criteria (BIC). The maximum-likelihood estimates of the Markov transition probabilities were computed from 100 boot-strapped samples and were then used to generate 50-yr precipitation occurrence series. The distributions of dry-and wet-spell lengths in the resulting series were then compared with observations using a two-sample Kolmogorov-Smirnov (K-S) test. The results suggest that the most parsimonious model, as identified by the BIC, usually (in approximately 68% of the cases) reproduced the wet-and dry-spell length distributions. However, the K-S test often indicated a second-order model when the BIC indicated a first-order model. In a smaller number of cases, the BIC indicated a higher-order model than the K-S test. In both cases, the differences were found to be due to the distribution of wet spells rather than dry spells," wrote J.T. Schoof and colleagues, Southern Illinois University ...read more

  2008 NOV 3 - (VerticalNews.com) -- "A slightly simplified form of Thomson's Lagrangian stochastic model (LSM) is presented for dispersion applications in three-dimensional (3D) flow fields. It is found that the Lagrangian velocity of a particle in 3D inhomogeneous Gaussian turbulence can be decomposed into the local Eulerian mean velocity U-Ei at the particle position and a velocity perturbation u(i)'," investigators in the United States report ...read more