Ozone and water vapor variability in the polar middle atmosphere observed with ground-based microwave radiometers

• Main Authors: Shi, Guochun, Krochin, Witali, Sauvageat, Eric, Stober, Gunter
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2023
• Subjects: article; Verlagsveröffentlichung; Merra; Ny-Ålesund; Svalbard; Ny Ålesund
• Online Access: https://doi.org/10.5194/egusphere-2023-149; https://noa.gwlb.de/receive/cop_mods_00064881; https://egusphere.copernicus.org/preprints/egusphere-2023-149/egusphere-2023-149.pdf

We present continuous ozone and water vapor measurements with the two ground-based radiometers GROMOS-C and MIAWARA-C at Ny-Ålesund, Svalbard (79° N, 12° E), that started in September 2015. Leveraging GROMOS-C and MIAWARA-C measurements, MERRA-2, and Aura-MLS datasets, we analyze the long-term behavior and interannual differences of ozone and water vapor and compile climatologies of both trace gases that describe the annual variation of ozone and water vapor at polar latitudes. A climatological comparison of the measurements from our ground-based radiometers with reanalysis and satellite data was performed. Overall differences between GROMOS-C and Aura-MLS ozone climatology are on the order of 10–15 % depending on the altitudes. For the water vapor climatology, MIAWARA-C shows the best agreement with Aura-MLS on average within 5 % throughout the upper stratosphere and mesosphere. The comparison to MERRA-2 yields an agreement that reveals discrepancies larger than 50 % above 0.2 hPa depending on the implemented radiative transfer schemes and other model physics. Furthermore, we perform a conjugate latitude comparison by defining a virtual station in the southern hemisphere at the geographic coordinate (79° S, 12° E) to investigate interhemispheric differences in the atmospheric compositions. Both trace gases show much more pronounced interannual and seasonal variability in the northern hemisphere than in the southern hemisphere. We estimate the effective water vapor transport vertical velocities corresponding to upwelling and downwelling periods driven by the residual circulation. In the northern hemisphere, the water vapor ascent rate is 3.42 ± 1.89 mm s−1 from MIAWARA-C and 4.64 ± 1.83 mm s−1 from Aura-MLS, and the descent rate is 4.98 ± 1.08 mm s−1 from MIAWARA-C and 5.40 ± 1.54 mm s−1 from Aura-MLS. The water vapor ascent and descent rates in the southern hemisphere are 5.22 ± 0.76 mm s−1 and 2.61 ± 1.44 mm s−1 from Aura-MLS, respectively. The water vapor transport vertical velocities analysis further reveals ...