Smoothed Sunspot NumberAn average of 13 monthly RI numbers, centered on
the month of concern.SunspotIn solar-terrestrial terms, an area seen as a dark spot on the photosphere of the sun. Sunspots
are concentrations of magnetic flux, typically occurring in bipolar
clusters or groups. They appear dark because they are cooler than
the surrounding photosphere.Sunspot Group Classification
- A: A small single unipolar sunspot or very small group of spots without penumbra.
- B: Bipolar sunspot group with no penumbra.
- C: An elongated bipolar sunspot group. One sunspot must have penumbra.
- D: An elongated bipolar sunspot group with penumbra on both ends of the group.
- E: An elongated bipolar sunspot group with penumbra on both ends. Longitudinal extent of penumbra exceeds 10 deg. but not 15 deg.
- F: An elongated bipolar sunspot group with penumbra on both ends. Longitudinal extent of penumbra exceeds 15 deg.
- H: A unipolar sunspot group with penumbra.
Sunspot NumberIn solar-terrestrial terms, a daily index of sunspot activity (R), defined as
R = k (10 g + s) where S = number of individual spots, g =
number of sunspot groups, and k is an observatory factor.Zurich Sunspot ClassificationIn solar-terrestrial terms, a sunspot classification system that has been
modified for SESC use.
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