EUV Jets and H Surges in Solar Micro

We analyzed simultaneous extreme-ultraviolet (EUV) data from the Transition Region and Coronal Explorer (TRACE) and H data from Big Bear Solar Observatory (BBSO). In the active region studied, we found several EUV jets which repeatedly occurred where pre-existing magnetic ux was \canceled" by newly emerging ux of opposite polarity. The jets look like Yohkoh soft X-ray jets, but are smaller and shorter-lived than X-ray jets. They have a typical size of 4000-10000 km and a transverse velocity of 50-100 km s ?1 , and a lifetime of 2-4 minutes. Each of the jets was ejected from a loop-like bright EUV emission patch at the moment the patch reached its peak emission. We also found dark H surges which are correlated with these jets. A careful comparison, however, revealed that the H surges are not co-spatial with the EUV jets. Instead, the EUV jets are identiied with bright jet-like features in the H line center. Our results support a picture in which H surges and EUV jets represent diierent kinds of plasma ejection | cool and hot plasma ejections along diierent eld lines| which must be dynamically connected to each other. We emphasize the importance of observed ux cancellation and a small erupting lament in understanding the acceleration mechanisms of EUV jets and H surges.