scholarly journals Critical conductance of the chiral two-dimensional random flux model

2008 ◽  
Vol 40 (5) ◽  
pp. 1335-1337 ◽  
Author(s):  
Ludwig Schweitzer ◽  
Peter Markoš
Keyword(s):  
Two Dimensional ◽  
Flux Model

scholarly journals Evaluation of a polynya flux model by means of thermal infrared satellite estimates

2011 ◽  
Vol 52 (57) ◽  
pp. 52-60 ◽  
Author(s):  
Thomas Krumpen ◽  
Sascha Willmes ◽  
Miguel Angel Morales Maqueda ◽  
Christian Haas ◽  
Jens A. Hölemann ◽  
...  
Keyword(s):  
Conservation Laws ◽  
Open Water ◽  
Thermal Infrared ◽  
Ice Thickness ◽  
Two Dimensional ◽  
Moderate Resolution ◽  
Flux Model ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Ice Production

AbstractWe test the ability of a two-dimensional flux model to simulate polynya events with narrow open-water zones by comparing model results to ice-thickness and ice-production estimates derived from thermal infrared Moderate Resolution Imaging Spectroradiometer (MODIS) observations in conjunction with an atmospheric dataset. Given a polynya boundary and an atmospheric dataset, the model correctly reproduces the shape of an 11 day long event, using only a few simple conservation laws. Ice production is slightly overestimated by the model, owing to an underestimated ice thickness. We achieved best model results with the consolidation thickness parameterization developed by Biggs and others (2000). Observed regional discrepancies between model and satellite estimates might be a consequence of the missing representation of the dynamic of the thin-ice thickening (e.g. rafting). We conclude that this simplified polynya model is a valuable tool for studying polynya dynamics and estimating associated fluxes of single polynya events.

Polynya flux model solutions incorporating a parameterization for the collection thickness of consolidated new ice

2000 ◽  
Vol 408 ◽  
pp. 179-204 ◽  
Author(s):  
NICHOLAS R. T. BIGGS ◽  
MIGUEL A. MORALES MAQUEDA ◽  
ANDREW J. WILLMOTT
Keyword(s):  
Steady State ◽  
Quantitative Agreement ◽  
Upper And Lower Bounds ◽  
Two Dimensional ◽  
Frazil Ice ◽  
Coastal Barrier ◽  
Coastal Polynya ◽  
Flux Model ◽  
Ice Velocity ◽  
Made In

Previous polynya flux models have specified a constant value for the collection thickness of frazil ice, H, at the polynya edge. In certain circumstances, this approach can cause the frazil ice depth, h, within the polynya, to exceed H, a result which violates assumptions made in the formulation of the ice flux balance equations at the polynya edge. To overcome this problem, a parameterization for H is derived in terms of the depth of frazil ice arriving at the polynya edge and the component, normal to the polynya edge, of the frazil ice velocity relative to the velocity of the consolidated ice pack. Thus, H is coupled to the unknown polynya edge. Using the new parameterization for H, an analysis of the unsteady one-dimensional opening of a coastal polynya is presented. Analytical solutions are also derived, using the new parameterization for H, for steady-state two-dimensional polynyas adjacent to a semi-infinite and finite-length coastal barrier, the latter case representing a prototype island. In all cases, the solutions show close qualitative and quantitative agreement with those derived using a constant value for H. However, the steady-state two-dimensional polynya edge can, in certain circumstances, exhibit a corner at the point where the offshore equilibrium width is reached. Precise conditions for the existence of a corner are derived in terms of the orientation of the frazil ice velocity (u) and the consolidated ice velocity (U). Upper and lower bounds are also obtained for the area of the steady-state island polynya, and it is shown that over a large range of orientations of u and U, the area exceeds that associated with the island polynya with constant H. Finally, two simulations of the St. Lawrence Island Polynya are presented using the new parameterization for H, and the results are compared with the H-constant theory.

Spectrophotometric measurements of objective-prism spectra

1966 ◽  
Vol 24 ◽  
pp. 118-119
Author(s):  
Th. Schmidt-Kaler
Keyword(s):  
Progress Report ◽  
Two Dimensional ◽  
Objective Prism ◽  
Made In

I should like to give you a very condensed progress report on some spectrophotometric measurements of objective-prism spectra made in collaboration with H. Leicher at Bonn. The procedure used is almost completely automatic. The measurements are made with the help of a semi-automatic fully digitized registering microphotometer constructed by Hög-Hamburg. The reductions are carried out with the aid of a number of interconnected programmes written for the computer IBM 7090, beginning with the output of the photometer in the form of punched cards and ending with the printing-out of the final two-dimensional classifications.

Introductory paper

1966 ◽  
Vol 24 ◽  
pp. 3-5
Author(s):  
W. W. Morgan
Keyword(s):  
Line Intensity ◽  
Classification Scheme ◽  
Two Dimensional ◽  
Spectral Classification ◽  
Dimensional Array ◽  
Rr Lyrae ◽  
Metallic Line ◽  
Introductory Paper ◽  
Parameter Varying ◽  
Definition Of

1. The definition of “normal” stars in spectral classification changes with time; at the time of the publication of theYerkes Spectral Atlasthe term “normal” was applied to stars whose spectra could be fitted smoothly into a two-dimensional array. Thus, at that time, weak-lined spectra (RR Lyrae and HD 140283) would have been considered peculiar. At the present time we would tend to classify such spectra as “normal”—in a more complicated classification scheme which would have a parameter varying with metallic-line intensity within a specific spectral subdivision.

A one-dimensional self-gravitating stellar gas

1966 ◽  
Vol 25 ◽  
pp. 46-48 ◽  
Author(s):  
M. Lecar
Keyword(s):  
Gravitational Field ◽  
Phase Space ◽  
Motion Picture ◽  
Space Distribution ◽  
Two Dimensional ◽  
One Dimensional ◽  
Phase Space Distribution ◽  
Dimensional Phase Space ◽  
The Mean

“Dynamical mixing”, i.e. relaxation of a stellar phase space distribution through interaction with the mean gravitational field, is numerically investigated for a one-dimensional self-gravitating stellar gas. Qualitative results are presented in the form of a motion picture of the flow of phase points (representing homogeneous slabs of stars) in two-dimensional phase space.

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