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https://doi.org/10.5194/egusphere-2025-4803
https://doi.org/10.5194/egusphere-2025-4803
09 Oct 2025
 | 09 Oct 2025
Status: this preprint is open for discussion and under review for Atmospheric Measurement Techniques (AMT).

Vertical Distribution of Heat and Sodium Fluxes in the Mesopause Region Measured by Sodium Lidar Over Hainan, China (109° E,19° N)

Xingjin Wang, Xin Fang, Wenhao Gao, Xianhang Chen, Tai Liu, Chengyun Yang, Tingdi Chen, Tao Li, and Xianghui Xue

Abstract. We present the first lidar-based characterization of seasonal variations in gravity-wave–induced vertical heat flux, sodium flux, and associated parameters – sodium density and temperature – between 80 and 100 km over Hainan, China (19° N, 109° E). Observations were carried out using a narrow band sodium lidar equipped with a laser frequency-locking and real-time monitoring module, achieving a root-mean-square (RMS) frequency stability of 0.5 MHz. Since February 2024, the system has provided continuous measurements of mesospheric sodium density, temperature, and vertical wind. The lidar results are generally consistent with coincident satellite measurements and model simulations at the near geographic location. Observations indicate that the highest temperatures below 95 km occur in May and November, with seasonal patterns closely matching from the SABER satellite data. The annual mean vertical heat flux shows two peak descent rates, −0.25 K m s⁻¹ at 83 km and −0.80 K m s⁻¹ at 89 km, corresponding to a cooling rate of approximately 40 K day-1 between 82 and 97 km. The sodium flux reveals two pronounced maxima exceeding −50 m s⁻¹ cm⁻³ at 88 and 90 km, with the resulting dynamical transport producing a maximum net sodium loss of 165 cm⁻³ h⁻¹ near 91 km. These findings provide direct evidence that the gravity-wave-breaking occurrences modulate both the thermal structure and chemical composition of the mesopause range.

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Xingjin Wang, Xin Fang, Wenhao Gao, Xianhang Chen, Tai Liu, Chengyun Yang, Tingdi Chen, Tao Li, and Xianghui Xue

Status: open (until 14 Nov 2025)

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Xingjin Wang, Xin Fang, Wenhao Gao, Xianhang Chen, Tai Liu, Chengyun Yang, Tingdi Chen, Tao Li, and Xianghui Xue
Xingjin Wang, Xin Fang, Wenhao Gao, Xianhang Chen, Tai Liu, Chengyun Yang, Tingdi Chen, Tao Li, and Xianghui Xue
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Short summary
This paper reports the deployment of the first narrowband sodium lidar in the low-latitude region of China. The lidar observations are compared with satellite measurements and atmospheric models, confirming the scientific credibility of these results. Calculations of vertical gravity wave heat and sodium fluxes are used to investigate the influence of the space environment. This lidar system will provide a new ground-based detection device for studying atmospheric environment above the area.
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