Analysis of Boundary Layer Height Calculation Methods Based on Boundary Layer Events over Yongxing Island

This study analyzed 10 years of sounding data from Yongxing Island to characterize temperature, humidity, and wind profiles in the atmospheric boundary layer (ABL). Our key findings are as follows. (1) Relative humidity inversions (RIs) were the most frequent events (99.8%), followed by surface-based temperature inversions (SBIs, 63%), elevated temperature inversions (EIs, 50%), and low-level jets (LLJs, 41%). (2) Higher near-surface temperature leads to a decrease in EI height, thickness, and intensity. (3) When EIs occurred, RIs were consistently observed beneath the base of the EIs. (4) The intensity of the RIs correlated negatively with surface humidity, whereas the intensity of the LLJs correlated positively with surface winds except in summer. (5) The boundary layer heights (BLHs) are best estimated using the potential temperature gradient method when EIs occur, otherwise, the Richardson number method is the best method. In contrast, the relative humidity and temperature gradient methods exhibit high dispersion or uncertainty. (6) The BLHs showed seasonal variability, peaking in winter (350–1450 m). These findings advance our understanding of ABL dynamics and BLH estimation over tropical islands.