Characterization of Meteorological Conditions at the Lenghu Site from Long-Term Multi-Station Observations

The Lenghu site has emerged as a prominent candidate for future large telescopes, making a detailed understanding of its meteorological environment essential as it directly determines telescope performance, observational efficiency, and data quality. Based on multi-year observations spanning nearly two decades (2005–2024) from six meteorological stations, we conducted a comprehensive analysis of temperature, humidity, atmospheric pressure, wind speed, and wind direction, which directly affect key observing conditions such as atmospheric seeing, infrared transparency, and telescope pointing stability, in order to characterize the site’s meteorological conditions. The diurnal temperature range is approximately 9 °C, with 90% of hourly nighttime variations within 0–1°C. Relative humidity exceeds 90% less than 1% of the time, with a median below 31%. Atmospheric pressure becomes increasingly stable with altitude. Winds are predominantly westerly at night and weaker than during the day, with median speeds of 2–4 m s−1. Strong wind events (≥15 m s−1) occur occasionally at mid-mountain levels, while the maximum recorded wind speed at the summit is 21.0 m s−1. We further calculated the nighttime dew-point temperature using ambient temperature and relative humidity, and inferred nighttime weather stability by comparing observed and theoretical pressures. The meteorological characteristics revealed by long-term, multi-station observations exhibit stable interannual and seasonal variations, indicating that the Lenghu site offers long-term, stable, and favorable conditions for astronomical observations. These results also provide valuable guidance for the construction, operation, and observational planning of future large telescopes.