Abstract:The temporal evolution of atmospheric convective boundary layer height (CBLH) has an important impact on weather and climate change, but there are few studies on the CBLH climatology in the Beijing Region. This study presents the CBLH climatology in Beijing by using high resolution ERA5 reanalysis data during 1992-2022. The ERA5 CBLH is first evaluated against radiosonde-derived CBLH. ERA5 can reproduce the CBLH variation characteristics by sounding reasonably well. Then, the interannual, seasonal and diurnal variations of the CBLHs, as well as the correlation between the CBLH and key meteorological parameters are analyzed. The results show that in the past 30 years, the CBLHs in spring and autumn have decreased at the rate of 61.6 m per decade and 13.1 m per decade, respectively, while that in summer and winter have increased at the rate of 2.9 m per decade and 7.7 m per decade, respectively. The median values of CBLH at noon in spring, summer, autumn, and winter are about 1700 m, 1100 m, 950 m, and 800 m, respectively. The CBLH in spring is the highest among the four seasons because of the large surface sensible heat flux and the weak atmospheric stability. By analyzing the relationship between CBLH and sensible heat flux, potential temperature lapse rate and difference of surface temperature and air temperature （Ts-Ta）, we have found that in spring, when the sensible heat flux increases by 100 W·m-2, the CBLH increases by 615 m; when the potential temperature lapse rate increases by 1 ℃·km-1, the CBLH increases by 1376 m; and when the Ts-Ta increases by 1℃, the CBLH increases by 175 m.