Soho observations of the structure and dynamics of sunspot region atmospheres

We present results from a study of the spatial distributions of line emissi on and relative line-of-sight velocity in the atmosphere above 17 sunspot r egions, from the chromosphere, through the transition region and into the c orona, based on simultaneous observations of ten EUV emission lines with th e Coronal Diagnostic Spectrometer - CDS on SOHO. We find that the spatial d istributions are nonuniform over the sunspot region and introduce the notat ion `sunspot loop' to describe an enhanced transition region emission featu re that looks like a magnetic loop, extending from inside the sunspot to th e surrounding regions. We find little evidence for the siphon flow. Attenti on is given to the time variations since we observe both a rapid variation with a characteristic time of a few to several minutes and a slow variation with a time constant of several hours to approximate to 1 day. The most pr ominent features in the transition region intensity maps are the sunspot pl umes. We introduce an updated criterion for the presence of plumes and find that 15 out of 17 sunspots contain a plume in the temperature range logT a pproximate to 5.2-5.6. The relative line-of-sight velocity in sunspot plume s is high and directed into the Sun in the transition region. Almost all th e sunspot regions contain one or a few prominent, strongly redshifted veloc ity channels, several of the channels extend from the sunspot plume to cons iderable distances from the sunspot. The flow appears to be maintained by p lasmas at transition region temperatures, moving from regions located at a greater height outside the sunspots and towards the sunspot. The spatial co rrelation is high to moderate between emission lines formed in the transiti on region lines, but low between the transition region lines and the corona l lines. From detailed comparisons of intensity and velocity maps we find t ransition region emission features without any sign of coronal emission in the vicinity. A possible explanation is that the emission originates in mag netic flux tubes that are too cold to emit coronal emission. The comparison s suggest that gas at transition region temperature occur in loops differen t from loops with coronal temperature. However, we cannot exclude the prese nce of transition region temperatures close to the footpoints of flux tubes emitting at coronal temperatures. Regions with enhanced transition region line emission tend to be redshifted, but the correlation between line emiss ion and relative line-of-sight velocity is weak. We extend our conditional probability studies and confirm that there is a tendency for line profiles with large intensities and red shifts (blue shifts) above the average to co nstitute an increasing (decreasing) fraction of the profiles as the wavelen gth shift increases.