Solar Irradiance Variability, Influenced by r Modes
| Autor: | Charles L. Wolff |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Convection
Physics 010504 meteorology & atmospheric sciences Synodic day Irradiance Beat (acoustics) Astronomy and Astrophysics Astrophysics Solar irradiance Rotation 01 natural sciences Solar cycle Amplitude Space and Planetary Science 0103 physical sciences 010303 astronomy & astrophysics 0105 earth and related environmental sciences |
| Zdroj: | The Astrophysical Journal. 870:20 |
| ISSN: | 1538-4357 |
| DOI: | 10.3847/1538-4357/aaee80 |
| Popis: | A spectrum of the four-decade solar irradiance record has a prominent cluster of power for periodicities near 1 yr. Correlating irradiance with a bandpass filter showed that periodicity values were not constant, but varied sinusoidally with each cycle lasting 14 ± 1 yr. The large modulation amplitude makes solar frequencies ≥1 yr(exp −1) hard to detect at the solar surface. After removing the modulation, a Lomb–Scargle spectrum exposed two true periodicities: 1.006 and 0.920 yr. They are interpreted as the synodic rotation periods of r modes of lowest angular degree (l = 1). The first propagates in the stable interior and the second in the convective envelope perturbed by its several flow fields. The rotational beat period of the two modes is about 10.9 yr. This is close to the average length of a solar cycle and possibly controls this average. The 1.006 yr periodicity dominates most of the filtered irradiance record but an abrupt change to about 0.8 yr occurs in mid-2010. Also found was evidence for higher-degree r modes (l = 2 to 8) and a curious sawtooth modulation with a recurrence period of 2.6 yr. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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