Abstract. Large wind shears around the mesopause region play
an important role in atmospheric neutral dynamics and ionospheric
electrodynamics. Based on previous observations using sounding rockets,
lidars, radars, and model simulations, large shears are mainly attributed to
gravity waves (GWs) and modulated by tides (Liu, 2017). Based on the
dispersion and polarization relations of linear GWs and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER)
temperature data from 2002 to 2019, a method of deriving GW-perturbed wind
shears is proposed. The zonal-mean GW-perturbed shears have peaks (13–17 ms−1 km−1) at around the mesopause region, i.e., at z = 90–100 km
at most latitudes and at z = 80–90 km around the cold summer mesopause. This
latitude–height pattern is robust over the 18 years and agrees with model
simulations. The magnitudes of the GW-perturbed shears exhibit year-to-year
variations and agree with the lidar and sounding rocket observations in a climatological sense but are 60 %–70 % of the model results in the zonal-mean
sense. The GW-perturbed shears are hemispherically asymmetric and have strong
annual oscillation (AO) at around 80 km (above 92 km) at the northern
(southern) middle and high latitudes. At middle to high latitudes, the peaks
of AO shift from winter to summer and then to winter again with increasing
height. However, these GW-perturbed shears may be overestimated because the
GW propagation direction cannot be resolved by the method and may be
underestimated due to the observational filter, sampling distance, and cutoff
criterion of the vertical wavelength of GWs.
Large wind shears and stabilities in the mesopause region observed by Na wind-temperature lidar at midlatitude
