We aim to investigate the connection between chromospheric and coronal dynamics by exploiting recent observations and analysis that have revealed the presence of ubiquitous rapid upflows with velocities of order 50-150 km/s in the lower solar atmosphere (De Pontieu et al., 2009a, McIntosh & De Pontieu, 2009a,b). We observed signatures of these events with a broad range of imaging and spectroscopic instruments (SOHO/SUMER, Hinode/SOT-EIS-XRT, and Swedish Solar Telescope, SST) in the chromosphere (in the form of spicules or RBEs -- rapid blue-shifted events, De Pontieu et al., 2009a, Rouppe van der Voort et al., 2009) and in the transition region (TR) and corona (in the form of blueward asymmetries of TR/coronal spectral line profiles, and propagating disturbances in coronal imaging). Preliminary analysis suggests that these upflows are part of a previously undetected, but relentless transfer of mass between the dense lower atmosphere and tenuous corona in which a potentially significant amount of plasma may be heated to coronal temperatures at very low heights, in the upper chromosphere, TR and low corona.
We propose to obtain coordinated measurements with SOT, EIS, XRT and SDO to address a variety of unresolved issues:
- Do these occur at the footpoint regions of loops across whole active regions, or only at the edges?
- How do the upflow speeds vary with temperature?
- How well correlated are the chromospheric upflow events (observed as Doppler shifts in H-alpha) to the faint upflowing signals observed in the TR and corona?
- How ubiquitous is the apparently sometimes quasi-periodic recurrence of these events, and on what timescale do they recur? Have these upflow events previously been interpreted as a signature of propagating slow-mode magnetoacoustic waves in coronal loops?
- How are these upflow events correlated with changes in the photospheric vector magnetic field? |
|