Neutral thermospheric dynamics observed with two scanning Doppler imagers: 2. Vertical winds

This article is the second in a series of three papers reporting on observations of the 630.0 nm thermospheric airglow emission by two spatially separated scanning Doppler imagers (SDI’s) in Alaska. In this article, line‐of‐sight wind measurements from these instruments in four common‐volume regions lying along the great circle joining the two observatories have been used to derive estimates of the vertical wind in those common‐volumes. These estimates are combined with the vertical winds measured directly in each of the station zeniths to resolve both the spatial and temporal variations of the vertical wind field. Data from four nights are presented as examples of the wave‐like oscillations and frequently high spatial correlations that are observed. A statistical study of data from the full 19‐night data set showed that the frequency of observing statistically significant correlation between vertical winds measured at separate locations decreased linearly with increasing separation. A linear fit to this trend indicated that for this particular location and orientation the largest separation over which statistically significant correlation would be expected to occur is approximately 540 km.