Simultaneous measurements of neutral winds from the Doppler shifts of the 15867 K (630. nm) emission of the night sky have been made at two midlatitude stations separated by about 26¿ in longitude and less than 1¿ in latitude (39.8¿ N, 105.5¿W and 40.13¿ N, 79.16¿W). Comparison of the measured winds show strong local time correlation and negligible universal time correlation, in particular for meridional winds. This behavior is expected for the thermosphere for solar-minimum, magnetically quiet conditions, when the strongest pressure forces driving the winds are caused by insolation. The results also show the basic assumption of longitudinal or zonal averaging of two-dimensional thermospheric models to be correct for at least the 26¿ longitudinal separation between the two stations. |