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Session 1 - Chromosphere, Corona, Flares.
Display session, Friday, June 27
Ballroom B, Chair: Charles Kankelborg

[1.20] Wave Propagation in the Chromosphere and Transition Region: Where Have All the Shock Waves Gone?

B. Fleck (ESA/SSD), S. Steffens, F. -L. Deubner (Univ. Würzburg), K. Wilhelm (MPAe), R. Harrison (RAL), J. Gurman (NASA/GSFC)

We present first results from a joint observing program (SOHO JOP 26) involving SUMER, CDS and EIT on SOHO, coordinated with ground-based observations at the Vacuum Tower Telescope at Izaña, Tenerife. The objective of this study is to characterize the wave propagation properties in the solar atmosphere, from the photosphere through the chromosphere up into the transition region. Particular emphasis is laid on the 3-min shock waves observed in the Ca II K line. How do they impact the transition region and what signature do they leave there and in the lower corona?

The ground-based measurements comprise high resolution time series (both filtergrams and spectrograms) in Ca II K, H\,\alpha and Mg\,b_2. With SUMER we ran four sequences covering different temperature regimes: a) O I 1302, O I 1306, Si II 1309, C I 1311, C II 1334, C II 1335, b) Si I 1256, N V 1242, O V 629 c) He I 584, C III 1175, O I 1152, d) H I 1025, O VI 1031, O VI 1037. With CDS we took spectral time series in O VI 554, He I 584, He II 607, Mg IX 368, and O V 629 as well as wide-slit (90\times240'') ``movies'' in He I 584, Mg IX 368 and O V 629, while EIT ran sub-field high cadence sequences in He II 304.

Program listing for Friday