Observation of MLT region winds and tides by the USTC Mengcheng meteor radar

Abstract

The atmospheric winds and waves in the mesosphere and lower thermosphere (MLT) region are essential for studying the dynamics and climate in the middle and upper atmosphere. The University of Science and Technology of China (USTC) meteor radar located at Mengcheng (33.36°N, 116.49°E) has been operating continuously since April 2014. More than 8 years of observation of mesospheric horizontal winds and tides are presented in this study. In addition, we present an intercomparison among the meteor radar observations and the Navy Global Environmental Model-High Altitude (NAVGEM-HA) analysis results. The meteor number at northern lower midlatitudes suffers from diurnal variations in meteor occurrence, with a high count rate in the local morning and a low rate during local afternoon-to-midnight. The meteor count rates show a clear annual variation, with a maximum in September–October and a minimum in February. The horizontal wind in the MLT region has dominant annual variations at lower midlatitudes, with the eastward wind during summer and the westward wind during winter above 84 km, and the eastward wind during winter and the westward wind during spring below 84 km. The meridional wind is northward during winter and southward during summer. The diurnal amplitude is dominant, followed by the semidiurnal tides at lower midlatitudes. The zonal and meridional diurnal tides show enhancements during spring (March) with amplitudes that can reach up to 40 m/s and 30 m/s and during autumn (September) with amplitudes that can reach up to 30 m/s and 25 m/s, respectively. The seasonal variations in diurnal tidal amplitude basically show characteristics that are strong during the equinox and weak during the solstice. The zonal and meridional semidiurnal tides are maximized during spring (April) and autumn (September) above 90 km.

Mesopause temperatures and relative densities at midlatitudes observed by the Mengcheng meteor radar

“…In addition, in Figure 7, we show the composite seasonal variation in zonal and meridional winds from 2014 to 2022 observed by the MCMR (e.g., Yi W et al, 2023) compared with the mesopause relative densities obtained from MLS measurements and temperatures observed by SABER. It is interesting to note that the mesopause density (as shown in Figure 7c) exhibits a structure similar to that of the mesopause zonal wind (as shown in Figure 7a): as the zonal wind flows eastward, the mesopause density decreases, and vice versa.…”

Mesospheric tide comparisons at low latitudes observed by two collocated meteor radars

“…The tidal components with periods of 24 h, 12 h and 8 h represent the diurnal, semidiurnal and terdiurnal tides, respectively (Baumgarten and Stober, 2019;Yi W et al, 2023).…”

Meteor Radar for Investigation of the MLT Region: A Review

“…The era of the current small-aperture specular meteor radar (SMR) can be considered to begin at the turn of the 21st century with the publication of a paper [76] describing a commercial 'all-sky' meteor radar, followed shortly after by another competing commercial radar [77]. The latter system has continued to be developed [78] with improved data acquisition [27], self-calibration [79], higher powers [80], and the ability to support multistatic operation [81]. Equipment of the type described by [70] was used by [82] to make the first multistatic meteor wind observations.…”

“…This means that temperature can be inferred from estimates of D in the meteor region if the pressure is known (the pressure climatology method [125]; and see e.g., [126]) or by using the gradient of logD with respect to height (the gradient method [127]). Likewise, density can be inferred if the temperature is known [80,128]. However, the simple situation described by Equations ( 1) and ( 8) is more complicated at some heights.…”