  This paper utilized the high temporal and spatial resolution temperature
profile data observed by the multi-channel microwave radiometer at the Large
High Altitude Air Shower Observatory (LHAASO) on the eastern slope of the
Tibetan Plateau from February to May and August to November 2021, combined with
the ERA5 reanalysis data products for the whole year of 2021, to study the
daily, monthly, and seasonal variations of the atmospheric boundary layer
height (ABLH). The results are as follows: (1) The ABLH on sunny days showed
obvious fluctuations with peaks and valleys. The ABLH continued to rise with
the increase of surface temperature after sunrise and usually reached its
maximum value in the afternoon around 18:00, then rapidly decreased until
sunset. (2) The average ABLH in April was the highest at about 1200 m, while it
was only around 600 m in November. The ABLH fluctuated greatly during the day
and was stable at around 400 m at night. The ABLH results obtained from ERA5
were slightly smaller overall but had a consistent trend of change with the
microwave radiometer. (3) The maximum ABLH appeared in spring, followed by
summer and autumn, and winter had the lowest value, with all peaks reached
around 14:00-15:00. These results are of great significance for understanding
the ABLH on the eastern slope of the Tibetan Plateau, and provide reference for
the absolute calibration of photon numbers of the LHAASO telescope and the
atmospheric monitoring plan, as well as for evaluating the authenticity and
accuracy of existing reanalysis datasets.
