edu.ucar.opensky::articles:17096 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-26T14:11:30.064229 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7j104fx Large wind shears and stabilities in the mesopause region observed by Na lidar at midlatitude 2010-10-09T00:00:00Z publication https://n2t.org/ark:/85065/d7j104fx https://doi.org/10.1029/2009JA014864 Yue, Jia author She, C. author Liu, Hanli author UCAR/NCAR - Library publisher Unexpected large horizontal winds and wind shears in the lower thermosphere have been observed by rocket soundings and lidars for decades. From 4 years of the Colorado State University sodium wind-temperature lidar data set (2002-2005, total of ~1600 nocturnal hours), we observed an altitude distribution of large wind velocity and wind shears between 80 and 105 km, similar to the results of chemical release experiments. Our lidar data show conclusively that when the observed wind shears are plotted as a function of squared Brunt-Vaisala frequency, N2, they are below the value corresponding to the Richardson number of 1/4, which is a necessary condition of the onset of dynamic instability. This suggests that large wind shears can be sustained in the region of high static stability, e.g., in the lower thermosphere, where large wind shears are often observed by the rocket sounding. The full-diurnal-cycle lidar data enables the extraction of tidal wave components with periods of 24 h, 12 h, 8 h and 6 h, therefore allowing us to reveal the strong correlation of 60%, between large wind shears (>50 m/s/km) and tidal waves. The lidar measured seasonal variation of N2 and tidal amplitudes in the mesosphere and lower thermosphere (MLT) are found to be consistent with the difference in altitude distribution of strong wind shears between winter and summer. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication An edited version of this paper was published by AGU. Copyright 2010 American Geophysical Union. None eng geoscientificInformation