Abstract: On the basis of the refractive index gradient method, the Arctic planetary boundary layer height (PBLH) from 2007 to 2019 was estimated using radio occultation data from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellite and was verified using Integrated Global Radiosonde Archive radiosonde observations. The spatiotemporal variation of the PBLH was analyzed, focusing on the potential relationship between PBLH, temperature inversion characteristics, and low cloud fraction (Low CF). The results are as follows: (1) PBLH over land and ocean was the highest in summer, second highest in autumn, third highest in spring, and the lowest in winter. (2) The intensity and frequency of Surface-based inversion (SBI) are higher in winter and autumn than in spring and summer, whereas the intensity of elevated inversion (EI) is higher in winter and summer than in spring and autumn. The frequency of EI is higher in summer and autumn than in winter and spring. (3) The monthly mean variations of PBLH and those of SBI and EI intensities over land and ocean exhibit opposite trends. The monthly variations of PBLH and Low CF cover over land are the highest in summer and the lowest in winter, but there is no obvious relationship between PBLH and Low CF over ocean. (4) Between the anomalies in Low CF amount over land and PBLH anomalies, there is a significant negative correlation in spring and a positive correlation in autumn. For each season over land, the anomalies of Low CF amount are negatively correlated with the anomalies of SBI intensity, but are only positively correlated with the anomalies of EI intensity in summer. However, over the ocean, anomalies of Low CF amount are only significantly negatively correlated with SBI intensity anomalies in autumn.

Key words: temperature inversions, low cloud fraction (Low CF), COSMIC occultation data, planetary boundary layer height, Arctic