JOP150 Dynamics and Seismology of the Solar Atmosphere COORDINATORS: Francesco Berrilli (berrilli@roma2.infn.it, tel. 39-0672594430) Alexander Kosovichev (sasha@quake.stanford.edu, tel. 1-650-7237667) Co-investigators: G. Consolini, P.F. Moretti, E. Pietropaolo INSTRUMENTS: MDI, THEMIS, TRACE, EIT RECEIVED: 4 October 2001 SCIENCE OBJECTIVES: It is generally believed that solar 5-min oscillations are excited by turbulent flows in granulation. There is observational evidence that the excitation sources correlate with dark lanes of granulation, and might be related to downdrafts associated with the dark lanes. However, the physical mechanism of excitation of the oscillations is not understood. In order to investigate the process of the excitation of solar oscillation the analysis of seismic events is essential. The evidence of a strong seismic downplume, related to a big flare, has been observed by MDI (Kosovichev and Zarkova, 1998) and high l-degree modes excitation has been reported too (Haber et al., 1988). As predicted by Wolff (1972) these events were a possible origin of free oscillations in the Sun. Particularly, in the framework of the origin of solar five-minute oscillations, the seismic flux has been found to be related to downflows in the intergranular lanes (Goode et al., 1998, Espagnet et al., 1996, Strous, Goode and Rimmele, 2000). This phenomenon has been invoked to explain the solar "background" in the intensity (I) velocity (V) phase difference spectra (Skartlien and Rast, 2000). Recently, the background has been investigated from a different approach: the local analysis (Moretti et al., 2000a,b,c). The correlation between the H-alpha bright points and the background locations has been found, but high resolution and multi-band simultaneous data are needed to confirm the results. In this context we plan to start a coordinate observing campaign involving different solar instrument: MDI, THEMIS, TRACE. Particularly, the project is focused on the study of the local intensity-velocity phase difference using high-resolution data at different heights in the solar atmosphere. We are planning coordinated observations of solar granulation and oscillations using SOHO/MDI and THEMIS/IPM instruments to study relations between the dynamics of solar granulation and wave excitation. The major goals of this project are: 1) identification of oscillation sources by observing propagating wave packets and distributions of the oscillation power; 2) studying correlations between the acoustic sources and various properties of solar convection, such as downdrafts, dark lanes and exploding granules; 3) search for waves propagating from the photosphere into the chromosphere and corona, and their interaction with the magnetic network. OBSERVATIONS: The basic procedure is to obtain simultaneous observations in several spectral lines formed at different heights in the solar atmosphere. MDI: Currently, for MDI we plan to run a three-variable campaign in the high-resolution field of view (hr_fe_me_ve). The MDI line (NiI, 6767.8) is formed at 200-300 km above the photosphere. For some periods we plan to run a line-scan campaign (hr_vel_lp_e2 or hr_mag_lp_e2) THEMIS: For THEMIS/IPM we plan to use CI 5380 line formed at the photospheric level (0 km), and chromospheric H-alpha line. The observations in the CI 5380 line will simulate the MDI observing sequence. The observations in H-alpha will be the two wings of this line. EIT: EIT will provide extra synoptic images, preferrably 171A filter images between 7:00 and 15:00 UT. TRACE: For objective [3] TRACE support is very important. We would like to run a series of 1600, 171, wl images. Referring THEMIS IPM observations we plan: Observations with a spatial resolution better than 0.5 arcsec. A synchronized time cadence, between the different instruments, for the different spectral points. A sampling rate for the spectral series of about 1 minutes (TBD). For IPM, 10 wavelength samples can be easily achieved in this time interval. The lines we selected for the observations are the C I 538.0 nm and H-alpha. The C I 538.0 nm line is used to have information near the surface of the sun (tau=1). 5 points along this profile are needed to perform a spectral analysis.Five points on the H-alpha (four points on the wings and the continuum) are used for a recognition of the chromospheric explosive events and produce the co-alignment between TRACE, MDI and THEMIS data. Synchronization of the observations is extremely important. TARGET SELECTION: The targets will be in the MDI high-resolution field. We are interested in both quiet sun and active regions. SCHEDULING: The observations are planned for May 2002. If possible we would like to use two weeks of the MDI 2002 Dynamics Program in May 2002. Bibliography Berghmans, D., Clette, F., Moses, D., 1998, Astrophys. J., 336, 1039 Chae, J, wang, H., Lee, C., Goode, P.R., Schouhle, U., 1998, Astrophys. J., 497, L109 Espagnet, O., Muller, R., Rouder, Th., Mein, N., Malherbe, J.M., 1996, Astron. & Astrophys., 313, 297 Haber, D.A., Toomre, J. Hill, F., Gough, D., 1988, ESA SP-286, 301 Goode, P.R., Strous, L.H., Rimmele, T.R., Stebbins, R.T., 1998, Astrophys. J., 495, L27 Kosovichev A.G. and Zarkova, V.V., 1998, Nature, 393, 317 Moretti, P.F., Cacciani, A., Hanslmeier, A., Messerotti, Otruba, W., Warmuth, A., 2000a, in "Dynamics of the Sun", A. Hanslmeier & M. Messerotti eds., Kluwer Academic publ., in press Moretti, P.F., M. Oliviero, G. Severino, and The MOF Development Group, 2000b, Solar 2000, Mem. S.A.It., in press Moretti, P.F., M. Oliviero, G. Severino, and The MOF Development Group, 2000c, in "Helio-and Asteroseismology at the Dawn of the Millennium", ESA SP-464, in press Skartlien and Rast, 2000, Astrophys. J., 535, 464 Strous, L.H., Goode, P.R., Rimmele, T.R., 2000, Astrophys. J., 535, 1000 Wolff, C.L., 1972, Astrophys. J., 176, 833 --