DYNAMIC PROPERTIES OF SOLAR SPICULES OBSERVED BY SUMER/SOHO

We present a study the dynamic properties of EUV spicules. The selected data were obtained as time se-ries in polar coronal holes by SUMER/SOHO. The short exposure time and the almost xed position allow the analysis of the spicule properties such as: occurrence, lifetime, Doppler velocity, etc. Our data reveal that spicules occur repeatedly at the same lo-cation with a birth rate of around 0.1/min and a lifetime ranging from 15 minutes down to a few min-utes. Most of them have a height between 1000 and 2000 above the limb, and some can reach a height of 2000 to 4000 as macrospicules. We are able to see some spicules showing a process of \falling after rising " in-dicated by the change of Doppler velocity signs. In addition, on the disk, the same data indicate that EUV spicules have a behaviour as brightenings, with increase of radiance and change of Doppler velocity if seen in time series radiance maps and Dopplergrams. Key words: Sun; spicules; transition region; coronal holes; EUV radiation. 1