Information theoretic approach to discovering causalities in the solar cycle
Abstract
The causal parameters and response lag times of the solar cycle dynamics are investigated with transfer entropy, which can determine the amount of information transfer from one variable to another. The causal dependency of the solar cycle parameters is bidirectional. The transfer of information from the solar polar field to the sunspot number (SSN) peaks at lag time (t) ~ 30-40 months, but thereafter it remains at a persistent low level for at least 400 months (~ 3 solar cycles) for the period 1906-2014. The latter may indicate the persistency of the polar fields from one cycle to the next. It may lend support to the idea that the polar fields from the last 3 or more solar cycles can affect the production of SSN of the subsequent cycle. Both the meridional flow speed and flux emergence (proxied by the SSN) transfer information to the polar field, but one transfers more information than the other, depending on the lag times. The meridional flow speed transfers more information to the polar field than SSN at t ~28-30 months and at t ~90-110 months, which may be consistent with some flux transfer dynamo models and some surface flux transport models. However, the flux emergence transfers more information to the polar field than the meridional flow at t ~60-80 months, which may be consistent with a recently developed surface flux transport model. The transfer of information from the meridional flow to SSN peaks at t ~110-120 months (~1 solar cycle), suggesting that the meridional flow can be used to predict SSN about one cycle ahead. Finally, we analyze the information flow in the Dikpati Flux Transport Dynamo model and compare with that from the observations.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMSH31E3349W
- Keywords:
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- 7536 Solar activity cycle;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7537 Solar and stellar variability;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7544 Stellar interiors and dynamo theory;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7594 Instruments and techniques;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY