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On the generation of umbral flashes and running penumbral waves.From a review of the observed properties of umbral flashes and running penumbral waves it is proposed that the source of these periodic phenomena is the oscillatory convection which Danielson and Savage (1968) and Savage (1969) have shown is likely to occur in the superadiabatic subphotospheric layers of sunspot umbras. Periods and growth rates are computed for oscillatory modes arising in a simple two-layer model umbra. The results suggest that umbral flashes result from disturbances produced by oscillatory convection occurring in the upper subphotospheric layer of the umbra, where the superadiabatic temperature gradient is much enhanced over that in lower layers, while running penumbral waves are due to oscillations in a layer just below this upper layer.
Document ID
19730059836
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Moore, R. L.
(Big Bear Solar Observatory Pasadena, Calif., United States)
Date Acquired
August 7, 2013
Publication Date
June 1, 1973
Publication Information
Publication: Solar Physics
Volume: 30
Subject Category
Space Sciences
Accession Number
73A44638
Funding Number(s)
CONTRACT_GRANT: NGR-05-002-034
CONTRACT_GRANT: NSF 24015
Distribution Limits
Public
Copyright
Other

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