SOHO CONTRIBUTION TO THE UNDERSTANDING OF MASS SUPPLY AND FLOWS IN THE SOLAR CORONA

We expect a variety of dynamic phenomena in the 'quiescent' non-flarin g corona. Plasma flows, such as sophon flows or convective flows of ch romospheric material evaporating into the corona, are expected wheneve r a pressure differences is established either between the footpoints or between the coronal and chromospheric segments of a coronal loop. S uch flows can induce phenomena of spatial and temporal brightness vari ability of the corona. In particular, evaporation induces a net mass i nput into the corona and consequently coronal density enhancements. Fl ows are also expected in the regions where energy is released during m agnetic reconnection. From the observational point of view the dynamic s of the solar atmosphere has been investigated in great detail mostly in the lower transition region with the HRTS, and during flares with the Solar Maximum Mission and Yohkoh. The high spectral, temporal and spatial resolution of the SOHO ultraviolet spectrometers should enable us in the near future to fill the gap providing a continuous coverage from the chromosphere to the corona, in the 10(4)-10(6) K domain, and therefore to best study the dynamics throughout the solar atmosphere.