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Analysing the effects of apodizing windows on local correlation tracking using nirvana simulations of convection

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dc.contributor.author Louis, R. E
dc.contributor.author Ravindra, B
dc.contributor.author Georgoulis, M. K
dc.contributor.author Kuker, M
dc.date.accessioned 2020-11-10T02:08:29Z
dc.date.available 2020-11-10T02:08:29Z
dc.date.issued 2015-04
dc.identifier.citation Solar Physics, Vol.290, No. 4, pp. 1135-1146 en_US
dc.identifier.issn 1573-093X
dc.identifier.uri http://prints.iiap.res.in/handle/2248/6716
dc.description Restricted Access © Springer http://dx.doi.org/10.1007/s11207-015-0659-2 en_US
dc.description The original publication is available at springerlink.com
dc.description.abstract We employ different shapes of apodizing windows in the local correlation tracking (LCT) routine to retrieve horizontal velocities using numerical simulations of convection. LCT was applied on a time sequence of temperature maps generated by the Nirvana code with four different apodizing windows, Gaussian, Lorentzian, trapezoidal, and triangular, with varying widths. In terms of correlations (between the LCT-retrieved and simulated flow field), the triangular and the trapezoidal perform the best and worst, respectively. By segregating the intrinsic velocities in the simulations on the basis of their magnitudes, we find that for all windows a significantly higher correlation is obtained for the intermediate and high-velocity bins and only modest or weak values in the low-velocity bins. The differences between the LCT-retrieved and simulated flow fields were determined spatially. They show large residuals at or close to the boundary of granules. The extent to which the horizontal flow vectors retrieved by LCT are similar to the simulated values entirely depends on the width of the central peak of the apodizing window for a given σ. Even though LCT suffers from a lack of spatial content, as seen in simulations, its simplicity and speed could serve as a viable first-order tool to probe horizontal flows. This would be an ideal tool for large data sets. en_US
dc.language.iso en en_US
dc.publisher Springer en_US
dc.subject Velocity fields en_US
dc.subject Photosphere en_US
dc.title Analysing the effects of apodizing windows on local correlation tracking using nirvana simulations of convection en_US
dc.type Article en_US


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