HIGH-RESOLUTION OBSERVATION OF DISK SPICULES .1. EVOLUTION AND KINEMATICS OF SPICULES IN THE ENHANCED NETWORK

We present measurements of a 75 minute sequence of CCD spicule observa tions at H alpha -0.65 Angstrom, line center, and +0.65 Angstrom. The observations were made in a region of enhanced network near disk cente r, where most spicules are longer and tilted further from the vertical than those in truly quiet Sun. Images were reregistered with a correl ation coefficient greater than 0.9. We identify the spicules as those elongated jets that radiate from elements of the magnetic network and are the main chromospheric features seen in the wing of H alpha. Doppl er images produced by red-blue subtraction show an upward radial veloc ity during the extension phase and a downward velocity during contract ion for most spicules. Therefore, the spicules are truly moving up and down. There were a few plagelike cells filled with weak H alpha emiss ion, weak magnetic fields, and no spicules. We also found many multipl e spicules. The data are presented with commentary on the accompanying videotape. We analyzed the data to understand the spicule lifetimes a nd trajectories. We found that the entire set of wavelengths and Doppl ergrams was required to separate overlapping spicules. Seventy-six of the 96 spicules studied appear in complete upward and downward traject ories. The evidence on motions is not conclusive. Some proper motions are well represented by ballistic trajectories with initial injection velocity about 40 km s(-1) for highly inclined spicules. The small dec elerations would require the spicules to be tilted typically 60 degree s-70 degrees from the line of sight. Since limb observations favor til ts around 30 degrees, our observations must favor spicules tilted grea tly from the radial, as one finds in these enhanced field regions. The positive correlation of lifetimes with projected lengths supports thi s model. However, the Dopplergrams show that the entire spicule rises and falls as a whole, which favors a fountain jet or some acceleration in the flux tube. The downward trajectory may be slightly offset towa rd the network center from the upward path. Bright points often appear at the bases of spicules at H alpha -0.65 Angstrom, but during the pe ak extension or receding phase of the spicule rather than the beginnin g; therefore, the spicule is not a surgelike phenomenon (surges are us ually initiated by H alpha brightening or a subflare, invariably in a bipolar feature). Further, the magnetic elements, which match the H al pha bright points exactly, show no change associated with the brighten ing. The geometry creates a problem for coronal heating models, as the spicule tops are at least 10'' displaced from the bright-point bases, but no such offset appears in the K line, for example. There is some evidence that the spicule is generated several hundred kilometers abov e the photosphere.