TRANSITION REGION LINE-SHIFTS IN THE REBOUND SHOCK SPICULE MODEL

Spectral emission lines created in the solar chromosphere - corona tra nsition region show net red-shifts. It has been proposed that this may be the result of the return of spicular material. We simulate a spicu le numerically using the rebound shock model and find that the resulti ng hydrodynamic evolution leads to a perceived up-flow in transition r egion spectral lines even though the average velocity in the line form ing region is directed downward. The explanation for this apparent par adox is found in the correlation between density and velocity in the w aves generated by the rebound shock 'spicule'.