Intercomparison of long-term ground-based measurements of total, tropospheric, and stratospheric ozone at Lauder, New Zealand

A comprehensive intercomparison study was conducted of total column ozone and vertical distribution measurements at Lauder station from 2000-2022, analyzing data from multiple ground-based instruments including FTIR, Dobson spectrophotometer, UV2, microwave radiometer, ozonesondes, and stratospheric lidar. Using FTIR as reference, we found strong agreement in total column measurements, with high correlations (>0.93) and low biases (-2% to -3%). While negative biases were observed in stratospheric columns (-1.2% to -6.8%), suggesting an underestimation of infrared spectroscopic line intensities, dispersions remained within 5%. No significant drifts were found in tropospheric measurements, though some notable drifts were observed in stratospheric measurements, particularly with lidar and microwave radiometer in the middle stratosphere and with Umkehr and lidar in the upper stratosphere. This study resolved approximately half of the trend differences noted in previous LOTUS research through analysis of sampling, vertical sensitivity, and temporal factors, demonstrating the importance of well-harmonized measurements for accurate trend detection.