Characteristics of the Arctic Planetary Boundary Layer Height From Multiple Radio Occultations

Using the quality-controlled radio occultation (RO) refractivity profiles from nine missions, this study extracts the planetary boundary layer height (PBLH) with the minimum refractivity gradient method during December 2006-November 2019 over the Arctic, investigates the spatiotemporal variations in the PBLH, and discusses the potential relationships of PBLH to sea ice concentration (SIC) and related atmospheric parameters. We find that the RO-derived Arctic PBLH is typically deeper in summer than in autumn, spring, and winter. Moreover, PBLH displays clearly synchronous seasonal cycle in all latitude zones over both land and ocean, whereas the PBLH seasonality in different latitude zones over ocean exhibits much different patterns to that over land. Significant increases in PBLH are typically detected in all latitude zones over the entire Arctic except for the 78 degrees N-84 degrees N over ocean. In general, PBLH over the Arctic Ocean is consistently negatively (positively) correlated with SIC [surface air temperature (SAT) and precipitable water vapor (PWV)] in each season. However, the response of PBLH to the variations in these parameters varies with the sea ice conditions. PBLH tends to be affected by the moisture advection and the surface radiative cooling in the open ocean and the solid ice pack, respectively, while the PBLH in the marginal ice zone typically has transitional features between the open ocean and the solid ice pack. Furthermore, variations in low cloud fraction (CF) appear to have no direct effect on PBLH over the Arctic Ocean.