Planetary Boundary Layer Height on the Northern Mount Qomolangma Region Retrieved From Wind LiDAR Observations

Abstract

A coherent Doppler wind LiDAR (Wind3D 6000) has been operating in the northern Mount Qomolangma region since 2023. We retrieved planetary boundary layer height (PBLH) from LiDAR observations collected from October 2023 to September 2025 using a hybrid algorithm combining signal‐to‐noise ratio (SNR)‐based thresholding and wavelet covariance transform (WCT). The method agrees well with the available daytime radiosonde measurements, although these radiosonde observations are limited to a short monsoon‐season period and therefore cannot fully validate all seasons. Case studies of a clear‐sky day, a cloudy day, and a strong‐wind episode show that the LiDAR‐derived PBLH captures rapid convective growth under clear skies, abrupt collapse under cloud‐limited conditions, and mechanically sustained deep layers during high winds. In contrast, ERA5 and MERRA‐2 show systematic differences in the timing and magnitude of these diurnal transitions. Composite statistics reveal a robust diurnal cycle, with a shallow nocturnal layer (∼300–400 m), rapid growth after sunrise, and an afternoon maximum of 1.5–1.8 km. Seasonally, daytime PBLH is lowest in winter, increases during spring, reaches its largest monthly mean in June, and becomes slightly lower during July and August when monsoon clouds and moisture are more frequent. ERA5 generally underestimates daytime PBLH, especially during the warm season, whereas MERRA‐2 and the LiDAR's default product overestimate it throughout the year. This 2‐year PBLH record provides an observational basis for understanding boundary layer development and evaluating atmospheric reanalysis products over complex high‐mountain terrain, despite limited nocturnal validation and weather‐related data gaps.