Dynamics of the solar convective envelope

The energy flux associated with any set of such linear modes which spans the solar envelope is known to be inconsistent with the structure implied by standard mixing-length theory. By suitably altering the superadiabaticity profile of the solar envelope, however, it is possible to establish a structure which is roughly compatible with energy transport by linear modes throughout the envelope, with modes of different length scales predominating at various levels of the envelope. In some models, the spectrum of sizes of the strongest modes is similar to the spectrum of observed motions in the solar photosphere. The mixing lengths associated with such models are not in constant ratio to the pressure scale height, but mixing lengths of either constant absolute length or in ratio to the distance to the boundary of the convective zone are suggested. The largest scale of observed solar motions, the differential rotation, is not amenable to such treatment, because the motion is strongly influenced by rotation, and because the large-scale redistribution of heat flux from pole to equator associated with it may strongly affect the basic state. It is possible to demonstrate, though, that the temperature structure of a convective envelope incorporating meridional circulation of a magnitude necessary to produce the solar differential rotation may be consistent with observations of near-uniformity of photospheric temperatures, even in the framework of standard mixing-length theory. The convective envelopes studied in various modifications are produced by an original program for generating stellar envelope models, discussed and presented