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Register a new userDiagnostic tools for 3D unstructured oceanographic data
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Most ocean models in current use are built upon structured meshes. It follows that most existing tools for extracting diagnostic quantities (volume and surface integrals, for example) from ocean model output are constructed using techniques and software tools which assume structured meshes. The greater complexity inherent in unstructured meshes (especially fully unstructured grids which are unstructured in the vertical as well as the horizontal direction) has left some oceanographers, accustomed to traditional methods, unclear on how to calculate diagnostics on these meshes. In this paper we show that tools for extracting diagnostic data from the new generation of unstructured ocean models can be constructed with relative ease using open source software. Higher level languages such as Python, in conjunction with packages such as NumPy, SciPy, VTK and MayaVi, provide many of the high-level primitives needed to perform 3D visualisation and evaluate diagnostic quantities, e.g. density fluxes. We demonstrate this in the particular case of calculating flux of vector fields through isosurfaces, using flow data obtained from the unstructured mesh finite element ocean code ICOM, however this tool can be applied to model output from any unstructured grid ocean code.
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The enrichment of Fe, relative to alpha-elements such as O and Mg, represents a potential means to determine the age of quasars and probe the galaxy formation epoch. To explore how ion{Fe}{2} emission in quasars is linked to physical conditions and abundance, we have constructed a 830-level ion{Fe}{2} model atom and investigated through photoionization calculations how ion{Fe}{2} emission strengths depend on non-abundance factors. We have split ion{Fe}{2} emission into three major wavelength bands, ion{Fe}{2} (UV), ion{Fe}{2}(Opt1), and ion{Fe}{2}(Opt2), and explore how the ion{Fe}{2}(UV)/ion{Mg}{2}, ion{Fe}{2}(UV)/ion{Fe}{2}(Opt1) and ion{Fe}{2}(UV)/ion{Fe}{2}(Opt2) emission ratios depend upon hydrogen density and ionizing flux in broad-line regions (BLRs) of quasars. Our calculations show that: 1) similar ion{Fe}{2}(UV)/ion{Mg}{2} ratios can exist over a wide range of physical conditions; 2) the ion{Fe}{2}(UV)/ion{Fe}{2}(Opt1) and ion{Fe}{2}(UV)/ion{Fe}{2}(Opt2) ratios serve to constrain ionizing luminosity and hydrogen density; and 3) flux measurements of ion{Fe}{2} bands and knowledge of ionizing flux provide tools to derive distances to BLRs in quasars. To derive all BLR physical parameters with uncertainties, comparisons of our model with observations of a large quasar sample at low redshift ($z<1$) is desirable. The STIS and NICMOS spectrographs aboard the Hubble Space Telescope (HST) offer the best means to provide such observations.
In this paper, beam diagnostic and monitoring tools developed by the MAX IV Operations Group are discussed. In particular, new beam position monitoring and accelerator tunes visualization software tools, as well as tools that directly influence the beam quality and stability are introduced. An availability and downtime monitoring application is also presented.
Taking advantage of recent important advances in the calculation of high-resolution spectral grids of stellar atmospheres at short wavelengths, and their implementation for population synthesis models, we briefly review here some special properties of ultraviolet emission in SSPs, and discuss their potential applications for identifying and tuning up effective diagnostic tools to probe distinctive evolutionary properties of early-type galaxies and other evolved stellar systems.
In this work, we develop two spectroscopic diagnostic methods to derive the peak reduced electric field in Transient Luminous Events (TLEs) from their optical signals. These methods could be used to analyze the optical signature of TLEs reported by spacecraft such as ASIM (ESA) and the future TARANIS (CNES). As a first validation of these methods, we apply them to the predicted (synthetic) optical signatures of halos and elves, two type of TLEs, obtained from electrodynamical models. This procedure allows us to compare the inferred value of the peak reduced electric field with the value computed by halo and elve models. Afterward, we apply both methods to the analysis of optical signatures of elves and halos reported by GLIMS (JAXA) and ISUAL (NSPO) spacecraft, respectively. We conclude that the best emission ratios to estimate the maximum reduced electric field in halos and elves are the ratio of the Second Positive System (SPS) of N$_2$ to First Negative System (FNS) of N$_2^+$, the First Positive System (FPS) of N$_2$ to FNS of N$_2^+$ and the Lyman-Birge-Hopfield (LBH) band of N$_2$ to FNS of N$_2^+$. In the case of reduced electric fields below 150~Td, we found that the ratio of the SPS of N$_2$ to FPS of N$_2$ can also be used to reasonably estimate the value of the field. Finally, we show that the reported optical signals from elves can be treated following an inversion method in order to estimate some of the characteristics of the parent lightning.
The current state-of-the-art of multi-wavelength diagnostic tools (evolutionary synthesis, photoionisation models) for massive star forming regions (HII regions, starbursts, etc.) and some of their input physics (especially model atmospheres) is reviewed. Analysis of stellar populations based on integrated spectra from both stellar features and nebular emission lines from the UV to IR are summarised. We stress the importance of template studies at various scales (from individual stars to well studied galaxies) and various wavelengths, to understand the processes operating in massive star forming regions and to reliably derive their properties.
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