scholarly journals Observations and Analysis of Uncorrelated Rain

2005 ◽  
Vol 62 (11) ◽  
pp. 4071-4083 ◽  
Author(s):  
Michael L. Larsen ◽  
Alexander B. Kostinski ◽  
Ali Tokay
Keyword(s):  
Correlation Function ◽  
Pair Correlation ◽  
Two Dimensional ◽  
Statistical Tool ◽  
Arrival Times ◽  
Temporal Precision ◽  
Spatially Correlated ◽  
Radar Meteorology ◽  
Rain Events ◽  
Using Data

Abstract Most microphysical models in precipitation physics and radar meteorology assume (at least implicitly) that raindrops are completely uncorrelated in space and time. Yet, several recent studies have indicated that raindrop arrivals are often temporally and spatially correlated. Resolution of this conflict must begin with observations of perfectly uncorrelated rainfall, should such “perfectly steady rain” exist at all. Indeed, it does. Using data with high temporal precision from a two-dimensional video disdrometer and the pair-correlation function, a scale-localized statistical tool, several ∼10–20-min rain episodes have been uncovered where no clustering among droplet arrival times is found. This implies that (i) rain events exist where current microphysical models can be tested in an optimal manner and (ii) not all rain can be properly described using fractals.

Molecular Dynamics Study of the Effect of Magnetic Field on the Static and Dynamical Properties of Two-Dimensional Coulomb Systems

1997 ◽  
Vol 492 ◽  
Author(s):  
Godfrey Gumbs ◽  
Girija S. Dubey
Keyword(s):  
Magnetic Field ◽  
Molecular Dynamics ◽  
Correlation Function ◽  
External Magnetic Field ◽  
Pair Correlation ◽  
Mean Square Displacement ◽  
Coulomb Systems ◽  
First Principles Calculation ◽  
Two Dimensional ◽  
The Magnetic Field

ABSTRACTMolecular dynamics simulations are used to examine the effect of a uniform perpendicular magnetic field on a two-dimensional (2D) interacting electron system and we analyze how the magnetic field affects the single-particle properties of the system. In this simulation, we include the effect of the magnetic field classically through the Lorentz force. Both the Coulomb interaction and the magnetic field are included directly in the electron dynamics to study their combined effect on the transport properties of the 2D system. Results are presented for the pair correlation function, the mean square displacement and the density correlation function, in the presence and absence of an external magnetic field. Our simulation results, obtained from a first-principles calculation, clearly show that the external magnetic field has no effect on the static properties, but it affects the dynamics.

scholarly journals Comparative Evaluation of the OTT PARSIVEL2 Using a Collocated Two-Dimensional Video Disdrometer

2017 ◽  
Vol 34 (9) ◽  
pp. 2059-2082 ◽  
Author(s):  
S.-G. Park ◽  
Hae-Lim Kim ◽  
Young-Woong Ham ◽  
Sung-Hwa Jung
Keyword(s):  
Heavy Rainfall ◽  
Drop Diameter ◽  
Two Dimensional ◽  
Radar Rainfall ◽  
Rain Gauges ◽  
Empirical Relations ◽  
Raindrop Size ◽  
Rain Events ◽  
Using Data ◽  
Differential Reflectivity

AbstractThe performance of the OTT second-generation Particle Size Velocity (PARSIVEL2) laser weather sensor is evaluated by comparing it with a collocated two-dimensional video disdrometer (2DVD) and rain gauges using data collected over a total of 36 rain events. A comparison of raindrop size distributions (DSDs) between the 2DVD and two PARSIVEL2 reveals good agreement for weak rainfall rates below approximately 10 mm h−1 and for midsize drops with diameters between 0.6 and 4.0 mm irrespective of rainfall rates, whereas the PARSIVEL2 produces overestimations of large drops with diameters above 4 mm during heavy rainfall above approximately 20 mm h−1. The resultant DSD parameters of the PARSIVEL2 present overestimations of the mean diameter Dm in the normalized gamma function and the maximum drop diameter Dmax, and underestimations of the intercept parameter Nw and total number of drops NT. Furthermore, how the characteristics of DSDs from the PARSIVEL2 affect the polarimetric radar variables, such as differential reflectivity ZDR and specific differential phase KDP, is examined, as well as how these characteristics affect empirical relations required in radar hydrometeorological applications such as quantitative rainfall estimations. Based on these examinations, it can be concluded that the OTT PARSIVEL2 still produces overestimations of large drops and underestimations of small drops during heavy rainfall, similar to older models of PARSIVEL, despite significant improvements to the PARSIVEL2 system, and furthermore that the uses of PARSIVEL2 measurements can act as a source of error in radar hydrometeorological applications such as radar rainfall estimations.

The two-dimensional pair correlation function for the Si(001) surface: computer simulation results

1994 ◽  
Vol 6 (6) ◽  
pp. 1083-1088 ◽  
Author(s):  
Jia Zhengming ◽  
Yang Genqing ◽  
Cheng Zhaonian ◽  
Liu Xianghuai ◽  
Zou Shichang
Keyword(s):  
Computer Simulation ◽  
Correlation Function ◽  
Pair Correlation Function ◽  
Pair Correlation ◽  
Two Dimensional ◽  
Simulation Results
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