  Spatially averaged (> 50'') EUV spectral lines in the transition region of
solar quiet regions are known to be redshifted. Because the mechanism
underlying this phenomenon is unclear, we require additional physical
information on the lower corona for limiting the theoretical models. To acquire
this information, we measured the Doppler shifts over a wide coronal
temperature range (log T[K]=5.7--6.3) using the spectroscopic data taken by the
Hinode EUV Imaging Spectrometer. By analyzing the data over the center-to-limb
variations covering the meridian from the south to the north pole, we
successfully measured the velocity to an accuracy of 3 km/s. Below log T[K] =
6.0, the Doppler shifts of the emission lines were almost zero with an error of
1--3 km/s; above this temperature, they were blueshifted with a gradually
increasing magnitude, reaching - 6.3 +/- 2.1 km/s at log T[K]=6.25.
