Sunspots

Sunspots are persistent coherent structures on the solar surface. They arise due to high magnetic fields generated within the convection layer of the sun which penetrate the photosphere. They are much cooler and darker than their surroundings. A typical sunspot has a few distinct features:

Umbra

The cool dark center of the sunspot is called the umbra. This is the region with the highest magnetic fields.

Penumbra

The penumbra surrounds the umbra and is brighter than the umbra but cooler and darker than the surrounding granulation.

Filaments

The filaments are long, thin, bright structures within the penumbra. They tend to move outwards from the umbra to the perimeter of the penumbra.

It is not well known how sunspots evolve. In our work, we specifically would like to discover what the underlying physical modes of evolution of a sunspot are, how the energy in the system is distributed among these modes, how the modes interact, and how we can determine them. The Karhunen-Loeve transform can help answer these questions.

Eigenfunction Analysis of Coherent Structures on the Solar Surface
Authoring NASA Official:Dr. Milton Halem, Chief, Earth and Space Data Computing Division
Contact:Marilyn Mack/Code 930 marilyn.j.mack.1@gsfc.nasa.gov