Statistical Study of the Midlatitude Mesospheric Vertical Winds Observed by the Wuhan and Beijing MST Radars in China

Abstract

Based on the long-term observations of the Wuhan and Beijing Mesosphere-Stratosphere-Troposphere (MST) radars, the statistic characteristics of the mesospheric vertical winds at midlatitudes are investigated for the first time. The vertical wind data come from the Wuhan MST radar (29.51°N, 114.13°E) during 2012-2017 and from the Beijing MST radar (39.75°N, 116.96°E) during 2012-2014. The subdaily, seasonal, and annual variations of the mesospheric vertical winds at Wuhan and Beijing are presented. No obvious subdaily and seasonal variations are found and the annual variations of the mean vertical winds are downward in most of time. The mean vertical winds at Wuhan become smaller in summer and turn to upward at some heights, while those of Beijing only become smaller in summer. The difference of summer vertical winds over Wuhan and Beijing is closely related to the gravity wave activity. The Wuhan MST radar is located to the east side of the Qinghai-Tibet plateau and also in the East Asian monsoon region, thus the mesospheric winds over Wuhan may experience more influence of gravity waves compared with those over Beijing. The possible bias sources in the vertical wind measurement of the two MST radars are carefully analyzed and the presented wind velocities are proved to be credible. The measured velocity magnitude is similar to other Very High Frequency radar observations, but much larger than that of the WACCM simulation. The Stokes drift, multicellular circulation structures, the wave influence on the radar echoes are raised as the potential sources for this discrepancy.

Statistical Characteristics of the Low‐Latitude E‐Region Irregularities Observed by the HCOPAR in South China

“…However, the daytime irregularities in summer with higher solar radiation have much higher occurrence rate than those of other seasons, indicating the complex driving mechanisms for the daytime E‐region irregularities. Moreover, in addition to the summer enhancement of the diurnal tide, the gravity wave activities also reach their maximum during summer months in middle and low‐latitudes of Asia (Sasi and Vijayan, 2001; Zhang et al., 2020). Gravity waves are also suggested as one of the excitation sources for the E‐region irregularities (Chen et al., 2014; Ogawa et al., 2005).…”

Design of the New MST Radar in Chinese Meridian Project

“…Two MST radars in Beijing and Wuhan have been developed and run in China for more than seven years with the support of the Chinese Meridian Project. They have well recorded the unique features of the mid-latitude mesospheric winds over China [42] . However, the low-latitude wind observations are still in lack.…”

“…Readers can access their data freely from the Meridian Project data center (https://data.meridianproject.ac.cn/). In the past years, the two MST radars have recorded abundant atmospheric echoes including the mesospheric echoes and achieved the expected target [24] [42] . Supported by the second phase of Chinese Meridian Project, a new powerful and functional MST radar with high reliability and expansibility is under construction.…”

The Possible Role of Turbopause on Sporadic‐E Layer Formation at Middle and Low Latitudes

“…We can see from Figure 9 that in addition to Wuhan, the variation of the Es layer height at other stations is consistent with that of “wave turbopause.” Based on Wuhan and Beijing MST radar, Zhang et al. (2020) investigated the seasonal variations of turbulent kinetic energy dissipation rate and found that the seasonal variations of turbulent kinetic energy dissipation rate at Wuhan is different compared to higher latitude Beijing. They proposed that Wuhan is located to the east side of the Qinghai‐Tibet Plateau and also in the East Asian monsoon region; thus, the mesospheric winds over Wuhan may experience more influence of gravity waves compared with those over Beijing.…”

“…By using the MST radar observations, Hocking (1985) and Fukao et al (1994) proposed a method to calculate the vertical eddy diffusivity in the mesosphere by radar observations. This method was subsequently adopted by MST radars and MF radars around the world (e.g., Hocking, 1990;Sasi & Vijayan, 2001;Selvaraj et al, 2016;Zhang et al, 2020). Basing on MST radar at Gadanki (13.5° N, 79.2° E), Sasi and Vijayan (2001) showed the summer maxima of eddy diffusion coefficients in the tropical mesosphere.…”