Vertical flows of supergranular and mesogranular scale observed on the sun with OSO 8

Steady flows have been observed at disk center on the quiet Sun using the University of Colorado Ultraviolet Spectrometer on OSO 8 and the diode-array instrument at Sacamento Peak Observatory. Simultaneous observations in Fe I lambda5576, Mg I lambda5173, and Si II lambda1817 allow us to compare time-average Doppler velocities over a height range of 1400 km from the photosphere to the middle chromosphere. It is shown that patterns of steady vertical velocity with the largest spatial scales of supergranulation are present in the middle chromosphere, where they correlate well with those seen lower in the atmosphere. Such patterns are seen to persist for at least 9 hr, with downflow generally occurring in regions of enhanced intensity, and upflow in the darker areas. Observed with 10'' x 20'' spatial resolution, the spatial rms velocity amplitudes increase from about 30 ms/sup -1/ in Fe I and Mg I to about 350 ms/sup -1/ in Si II. Higher spatial resolution reveals that variations on smaller horizontal scales of about 10'' are also present in the Si II velocity data, although these do not correlate directly with the mesogranulation seen in Fe I and Mg I. With 2'' x 20'' resolution, the spatial rms of the time-averaged velocity is about 700 ms/sup -1/, compared with about 40 ms/sup -1/ in Fe I and 50 ms/sup -1/ in Mg I.