Articles | Volume 17, issue 17
Research article
01 Sep 2017
Research article |  | 01 Sep 2017

Comparison of ozone profiles and influences from the tertiary ozone maximum in the night-to-day ratio above Switzerland

Lorena Moreira, Klemens Hocke, and Niklaus Kämpfer

Abstract. Stratospheric and middle-mesospheric ozone profiles above Bern, Switzerland (46.95° N, 7.44° E; 577 m) have been continually measured by the GROMOS (GROund-based Millimeter-wave Ozone Spectrometer) microwave radiometer since 1994. GROMOS is part of the Network for the Detection of Atmospheric Composition Change (NDACC). A new version of the ozone profile retrievals has been developed with the aim of improving the altitude range of retrieval profiles. GROMOS profiles from this new retrieval version have been compared to coincident ozone profiles obtained by the satellite limb sounder Aura Microwave Limb Sounder (MLS). The study covers the stratosphere and middle mesosphere from 50 to 0.05 hPa (from 21 to 70 km) and extends over the period from July 2009 to November 2016, which results in more than 2800 coincident profiles available for the comparison. On average, GROMOS and MLS comparisons show agreement generally over 20 % in the lower stratosphere and within 2 % in the middle and upper stratosphere for both daytime and nighttime, whereas in the mesosphere the mean relative difference is below 40 % during the daytime and below 15 % during the nighttime. In addition, we have observed the annual variation in nighttime ozone in the middle mesosphere, at 0.05 hPa (70 km), characterized by the enhancement of ozone during wintertime for both ground-based and space-based measurements. This behaviour is related to the middle-mesospheric maximum in ozone (MMM).

Short summary
GROMOS (GROund-based Millimeter-wave Ozone Spectrometer) has provided ozone profiles for the Network for the Detection of Atmospheric Composition Change since 1994. A new retrieval version for ozone profiles aims to improve the altitude range of profiles. We performed a comparison between coincident profiles of GROMOS and Aura MLS, resulting in agreement within 2% in the mid- and upper stratosphere from 2009 to 2016. We also observed extensions of the tertiary ozone maximum at midlatitudes.
Final-revised paper