34th Solar Physics Division Meeting, June 2003
Session 7 Photosphere and Chromosphere I
Poster, Monday, June 16, 2003, 3:30-5:00pm, Mezzanine

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[7.03] Photospheric Sources of Chromospheric Dynamics in the Internetwork

A.C. Cadavid, J.K. Lawrence (California State University Northridge), T.E. Berger (Lockheed Martin Solar and Astrophysics Laboratory), A. Ruzmaikin (Jet Propulsion Laboratory)

We analyze a unique 9 hr sequence of near simultaneous, high resolution and high cadence G-band and K-line solar filtergrams together with magnetograms of lower cadence and resolution, taken with the SVST. We investigate an internetwork region characterized by magnetic fields with strength < 150 Gauss and focus on the phenomena surrounding discrete photospheric darkening ``events'' in G-band intensities. 72 % of the darkenings are followed after 2 min by K-line brightenings. In the remaining cases the darkenings are instead preceded by K-line brightenings 2 min earlier. In both cases the preceding and following G-band minima are each associated with transient magnetic enhancements, and thus, presumably, photospheric inflows followed by outflows. The magnetic field appears to have no role in coupling the photospheric phenomena to the chromosphere, and acts as a passive tracer of horizontal photospheric flows that converge on the photospheric darkening events and then rebound. The timing and coupling of the photospheric darkenings and chromospheric brightenings appear to be regulated by a pre-existing 4 min oscillation of the solar atmosphere. Other oscillations with periods in the range 1-8 min also are present, and in general the wave power is doubled at the time of an event. At short periods temporal structure is resolved. Our results favor an acoustic source for enhanced amplitudes of K-line intensity oscillations.


The author(s) of this abstract have provided an email address for comments about the abstract: ana.cadavid@csun.edu

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