Intercomparison of <scp>CL31</scp> and <scp>CL51</scp> ceilometers and impact of installation angle on cloud base height measurement agreement

Abstract Lowest‐layer cloud base height (CBH) measurements obtained between July 2018 and December 2019 from four ceilometers at the Korea Standard Meteorological Observatory were compared to determine how ceilometer installation angle differentially affects CBH measurements. Analysis of CBH data by installation angle (vertical/tilted) showed important inconsistencies in the measurements, even for devices of the same model. Additionally, CL51 and CL31, which have unified installation angles, showed more consistent measurements within the overlapping range of 0 to 7.62km, and installation based on the manufacturer‐recommended tilted angle improved measurement agreement under precipitation. Therefore, the ceilometer installation angle (12°) affects CBH observation quality.