## 5 Conclusions  
Using CDWL, a two-year stable observation experiment was conducted out on the southern edge of the TD. The MLH during the daytime was retrieved by using the TKEDR threshold method and statistically analyzed with the wind speed, wind direction, atmospheric temperature, relative humidity, and horizontal visibility obtained from the ground weather station. It is found that the proportion of horizontal visibility (<10 km), wind speed (>3.5 m/s), and MLH (<1 km) in the daytime of the study site reached 50.7%, 10.19%, and 56.96%, respectively. These data fully illustrate the severity of local dust pollution. From the hourly analysis of the daytime, the average maximum MLH occurs between 16:00 BJT and 17:00 BJT. The MLH exhibits a unimodal distribution, and the decrease rate of the MLH after noon is much greater than the increase rate before noon due to the characteristics of the desert underlying surface. In terms of the average monthly change in data, the average wind speed in March increased most significantly and peaked at 2.8 m/s in May. Although the average temperature reached its highest point in July (33.83 \({}^{\circ}\)C), the average wind speed was stronger in June, and the deep ML (>4 km) was also formed most frequently. From September to December, the cooling rate is fast (from 30.61 \({}^{\circ}\)C to 2.45 \({}^{\circ}\)C). From the seasonal perspective, the daytime winds at the study site were dominated by west-pathway (the probability of occurrence is 24.86%) and east-pathway (39.67%) winds due to the blocking effect of the Tibetan plateau and the surrounding mountains. Although the average daytime temperature was the highest in summer, the strong east-pathway airflow and west-pathway airflow occurred more frequently in spring, which made the distribution characteristics of MLH in spring (>3 km, 22.13%) similar to those in summer (>3 km, 20.38%). In the analysis of the relationship between MLH and surface meteorological elements, high temperatures (>28 \({}^{\circ}\)C) provide sufficient thermal conditions for the development of the ML. The relative humidity that most contributes to MLH higher than 3 km ranges between 10% and 20%. In conditions of floating dust or blowing dust weather, with visibility ranging from 1-10 km, the ML is significantly influenced. Compared with the stronger west-pathway airflow, the east-pathway airflow conforms to the mechanism of the low-level jet, which contributes more to the formation of a deep ML. When specifically considering MLH around 3 km, there is a clear trend of a concentrated distribution in temperature and relative humidity. Figure 8: During the daytime, the probability density distribution between the hourly mean mixed layer height and the ground meteorological elements in spring and summer. **(a)** Atmospheric temperature versus MLH. **(b)** Relative humidity versus MLH. **(c)** Near-surface wind speed versus MLH. **(d)** Horizontal visibility versus MLH. Overall, the study results reveal the distribution characteristics of daytime MLH in the southern edge of the TD and provide important data supplementation for meteorological research on the TD. However, this paper only discussed the influence of near-surface meteorological data on the MLH during the daytime and did not consider the effects of nighttime conditions, different weather patterns, and varying heights on the MLH. The follow-up work will combine the multi-source data to further explore the variation under different weather conditions, as well as the differences between the uphill airflow and the downhill airflow during the ML development. Conceptualization, H.X. ; methodology, L.S. and J.Y. ; experiment, L.S. ; software, L.S. ; formal analysis, L.S. ; investigation, L.S. and Y.W. ; resources, L.S., A.M. and Q.H. ; data curation, L.S. ; writing--original draft preparation, L.S. ; writing--review and editing, H.X., J.Y., Y.W., A.M. and Q.H. ; visualization, L.S. ; supervision, H.X. All authors have read and agreed to the published version of the manuscript.