Temporal Evolution of Sunspot Areas and Estimation of Related Plasma Flows

The increased amount of information provided by ongoing missions such as the Solar Dynamics Observatory (SDO) represents a great challenge for the understanding of basic questions such as the internal structure of sunspots and how they evolve with time. Here, we contribute with the exploitation of n...

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Bibliographic Details
Published in:Solar physics 2014-05, Vol.289 (5), p.1531-1542
Main Authors: Gafeira, R., Fonte, C. C., Pais, M. A., Fernandes, J.
Format: Article
Language:English
Subjects:
Astrophysics and Astroparticles
Atmospheric Sciences
Estimating techniques
Evolutionary biology
Physics
Physics and Astronomy
Plasma
Solar physics
Space Exploration and Astronautics
Space Sciences (including Extraterrestrial Physics
Sunspots
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Summary:The increased amount of information provided by ongoing missions such as the Solar Dynamics Observatory (SDO) represents a great challenge for the understanding of basic questions such as the internal structure of sunspots and how they evolve with time. Here, we contribute with the exploitation of new data, to provide a better understanding of the separate growth and decay of sunspots, umbra, and penumbra. Using fuzzy sets to compute separately the areas of sunspot umbra and penumbra, the growth and decay rates for active regions NOAA 11117, NOAA 11428, NOAA 11429, and NOAA 11430 are computed from the analysis of intensitygrams obtained by the Helioseismic and Magnetic Imager onboard SDO. A simplified numerical model is proposed for the decay phase, whereby an empirical irrotational and uniformly convergent horizontal velocity field interacting with an axially symmetric and height-invariant magnetic field reproduces the large-scale features of the much more complex convection observed inside sunspots.
ISSN:0038-0938
1573-093X
DOI:10.1007/s11207-013-0440-3