16 research outputs found

    3D modeling of magnetic field lines using SOHO/MDI magnetogram images

    Get PDF
    YesSolar images, along with other observational data, are very important for solar physicists and space weather researchers aiming to understand the way the Sun works and affects Earth. In this study a 3D modelling technique for visualizing solar magnetic field lines using solar images is presented. Photospheric magnetic field footpoints are detected from magnetogram images and using negative and positive magnetic footpoints, dipole pairs are associated according to their proximity. Then, 3D field line models are built using the calculated dipole coordinates, and mapped to detected pairs after coordinate transformations. Final 3D models are compared to extreme ultraviolet images and existing models and the results of visual comparisons are presented

    Representation of solar features in 3D for creating visual solar catalogues

    Get PDF
    YesIn this study a method for 3D representation of active regions and sunspots that are detected from Solar and Heliospheric Observatory/Michelson Doppler Imager magnetogram and continuum images is provided. This is our first attempt to create a visual solar catalogue. Because of the difficulty of providing a full description of data in text based catalogues, it can be more accurate and effective for scientist to search 3D solar feature models and descriptions at the same time in such a visual solar catalogue. This catalogue would improve interpretation of solar images, since it would allow us to extract data embedded in various solar images and visualize it at the same time. In this work, active regions that are detected from magnetogram images and sunspots that are detected from continuum images are represented in 3D coordinates. Also their properties extracted from text based catalogues are represented at the same time in 3D environment. This is the first step for creating a 3D solar feature catalogue where automatically detected solar features will be presented visually together with their properties

    Solar flare prediction using advanced feature extraction, machine learning and feature selection

    Get PDF
    YesNovel machine-learning and feature-selection algorithms have been developed to study: (i) the flare prediction capability of magnetic feature (MF) properties generated by the recently developed Solar Monitor Active Region Tracker (SMART); (ii) SMART's MF properties that are most significantly related to flare occurrence. Spatio-temporal association algorithms are developed to associate MFs with flares from April 1996 to December 2010 in order to differentiate flaring and non-flaring MFs and enable the application of machine learning and feature selection algorithms. A machine-learning algorithm is applied to the associated datasets to determine the flare prediction capability of all 21 SMART MF properties. The prediction performance is assessed using standard forecast verification measures and compared with the prediction measures of one of the industry's standard technologies for flare prediction that is also based on machine learning - Automated Solar Activity Prediction (ASAP). The comparison shows that the combination of SMART MFs with machine learning has the potential to achieve more accurate flare prediction than ASAP. Feature selection algorithms are then applied to determine the MF properties that are most related to flare occurrence. It is found that a reduced set of 6 MF properties can achieve a similar degree of prediction accuracy as the full set of 21 SMART MF properties

    Annual Variation in the Diversity, Species Richness and Composition of the Phytoplankton Assemblages in the Izmir Bay (Eastern Aegean)

    No full text
    WOS: 000296070300014In this study, qualitative and quantitative characteristics of phytoplankton community structure and environmental factors which have influences on its distribution and the changes in Izmir Bay (Aegean Sea) were investigated. The water samples were collected seasonally between January 1998 and December 2001 from 3 sampling sites (from surface, -5 m, -10 in and -15 m). During the study period, a total of 115 taxa from three algal classes, Cyanophyceae, Dinophyceae and Bacillariophyceae were determined. Spatio-temporal phytoplankton community composition in the bay was often dominated by dinoflagellates but shift to diatom dominance was observed in some periods, particularly in spring and winter. The Wastewater Treatment Plant (WTP) began to treat domestic and industrial wastes since early 2000. The sampling periods of the study include both before and after the activation of treatment plant. Although WTP is sufficient for removal of nitrogen from the wastes, it is inadequate for removal of phosphate. This is also compatible with the decreasing N/P ratios observed during 2000-2001 in the middle and inner bays. Therefore, the decrease in the ratios caused by treatment plant, affects the species diversity of both dinoflagellat and diatom assemblages. The student's t-tests and the discriminant analyses outcome from different stations and years demonstrate statistically significant variances at a P <= 0.05 probability level. These results indicated that the considerable improvements should be expected in the next years.Izmir Metropolitan MunicipalityBelediyelerThis study has been supported by Izmir Metropolitan Municipality within the framework of the Izmir Bay Marine Research Project. We thank the scientists and the crew of the R/V "Koca Piri Reis" during the cruises
    corecore