Sökning: "sunspots data"

Hittade 4 avhandlingar innehållade orden sunspots data.

  1. 1. Testing for Periodicity and Trend in Long-Memory Processes

    Författare :Abdullah Almasri; Statistiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Statistics; temperature data.; sunspots data; wind speed data; varve data; Siegel’s test; Fisher’s test; periodogram; Fractional difference process; Discrete wavelet transform; operations research; programming; actuarial mathematics; Statistik; operationsanalys; programmering; aktuariematematik; Wavelets; Statistik;

    Sammanfattning : This thesis presents methods of testing the periodicity and trend for the time series, which exhibit dependence over long periods of time. Many such processes can be modeled by a class of models called fractionally differenced processes. LÄS MER

  3. 2. Imaging spectropolarimetry of solar active regions

    Författare :Gautam Narayan; Göran Scharmer; Rolf Schlichenmaier; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sun; Spectropolarimetry; Solar magnetic fields; Sunspots; Plages; Solar physics; Solfysik; Astronomy; astronomi;

    Sammanfattning : Solar magnetic fields span a wide range of spatial scales from sunspots and plages to magnetic bright points. A clear understanding of the physical processes underlying the evolution of these magnetic features requires high-resolution spectropolarimetric observations of solar active regions and comparisons with synthetic data from simulations. LÄS MER

  4. 3. Three-dimensional mapping of fine structure in the solar atmosphere

    Författare :Vasco M. J. Henriques; Dan Kiselman; Göran Scharmer; Hector Socas-Navarro; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sun; sunspots; Swedish 1-meter Solar Telescope; active regions; image processing; sunspot penumbra; Astronomy; astronomi;

    Sammanfattning : The effects on image formation through a tilted interference filter in a converging beam are investigated and an adequate compensation procedure is established. A method that compensates for small-scale seeing distortions is also developed with the aim of co-aligning non-simultaneous solar images from different passbands. LÄS MER

  5. 4. Flux emergence: flares and coronal mass ejections driven by dynamo action underneath the solar surface

    Författare :Jörn Warnecke; Axel Brandenburg; Dikpati Mausumi; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Astronomy; astronomi; teoretisk astrofysik; Theoretical Astrophysics; Space and Plasma Physics; rymd- och plasmafysik;

    Sammanfattning : Helically shaped magnetic field structuresknown as coronal mass ejections (CMEs) are closely related to so-called eruptive flares. On the one hand, these events are broadly believed to be due tothe buoyant rise of magnetic flux tubes from the bottom of the convection zone to the photosphere where they form structures such as sunspots. LÄS MER