34th Solar Physics Division Meeting, June 2003
Session 11 Photosphere and Chormosphere II
Oral, Tuesday, June 17, 2003, 1:30-3:30pm, Auditorium

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[11.01] The Violent Solar Chromosphere

W Kalkofen (Harvard-Smithsonian CfA)

Two different types of models have been proposed to describe the quiet solar chromosphere: Simulating the dynamics and the temperature structure resulting from shock waves gives a negative average temperature gradient with respect to height (\nablaz T <0) and violent temperature fluctuations (\delta T ~10,000 K); modeling based on the emergent spectrum gives a positive gradient (\nablaz T>0,\ z>0.5 Mm) and modest fluctuations (\delta T ~300 K). Clearly, these two models are incompatible with one another. The model of the dynamics claims that the traditional temperature structure of the chromosphere (\nablaz T>0) is an illusion created by time averaging of the emission. But the dissipation and radiative emission associated with the dynamics make only a minor contribution to chromospheric heating and the emergent radiation. In addition, in a typical supergranulation cell, the dynamics is confined to 10 to 20 regions (grains) with a combined filling factor ranging from 1% in the photosphere to 50% in the upper chromosphere. In the middle chromosphere (z=1~Mm), 90% to 95% of the medium falls outside the calcium grains and thus, according to the dynamical model, has no chromosphere, i.e., \nablaz T <0.

This paper discusses observational constraints on the temperature structure of the quiet solar chromosphere.

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Bulletin of the American Astronomical Society, 35 #3
© 2003. The American Astronomical Soceity.