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

Moreira, Lorena; Hocke, Klemens; Kämpfer, Niklaus

doi:10.5194/acp-17-10259-2017

Cited by 9 publications

(6 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, we have to keep in mind that fewer instruments (only SOMORA and Aura/MLS) provide data for comparison above 2 hPa, which makes the anomaly detection less robust at these altitudes, especially prior to the start of Aura/MLS measurements in 2004. Our results are consistent with those reported by Moreira et al (2017). They compared GROMOS with Aura/MLS data and also observed positive deviations of GROMOS in the middle stratosphere in 2014 and 2015 as well as a negative deviation in the upper stratosphere in 2016.…”

Section: Comparison Of Different Data Setssupporting

confidence: 93%

Ground-based ozone profiles over central Europe: incorporating anomalous observations into the analysis of stratospheric ozone trends

et al. 2019

Self Cite

View full text Add to dashboard Cite

Abstract. Observing stratospheric ozone is essential to assess whether the Montreal Protocol has succeeded in saving the ozone layer by banning ozone depleting substances. Recent studies have reported positive trends, indicating that ozone is recovering in the upper stratosphere at mid-latitudes, but the trend magnitudes differ, and uncertainties are still high. Trends and their uncertainties are influenced by factors such as instrumental drifts, sampling patterns, discontinuities, biases, or short-term anomalies that may all mask a potential ozone recovery. The present study investigates how anomalies, temporal measurement sampling rates, and trend period lengths influence resulting trends. We present an approach for handling suspicious anomalies in trend estimations. For this, we analysed multiple ground-based stratospheric ozone records in central Europe to identify anomalous periods in data from the GROund-based Millimetre-wave Ozone Spectrometer (GROMOS) located in Bern, Switzerland. The detected anomalies were then used to estimate ozone trends from the GROMOS time series by considering the anomalous observations in the regression. We compare our improved GROMOS trend estimate with results derived from the other ground-based ozone records (lidars, ozonesondes, and microwave radiometers), that are all part of the Network for the Detection of Atmospheric Composition Change (NDACC). The data indicate positive trends of 1 % decade−1 to 3 % decade−1 at an altitude of about 39 km (3 hPa), providing a confirmation of ozone recovery in the upper stratosphere in agreement with satellite observations. At lower altitudes, the ground station data show inconsistent trend results, which emphasize the importance of ongoing research on ozone trends in the lower stratosphere. Our presented method of a combined analysis of ground station data provides a useful approach to recognize and to reduce uncertainties in stratospheric ozone trends by considering anomalies in the trend estimation. We conclude that stratospheric trend estimations still need improvement and that our approach provides a tool that can also be useful for other data sets.

show abstract

Section: Comparison Of Different Data Setssupporting

confidence: 93%

Ground-based ozone profiles over central Europe: incorporating anomalous observations into the analysis of stratospheric ozone trends

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…For both instruments still, the differences with the convolved MLS profiles are smaller in autumn and winter than in spring and summer when the absorption by the troposphere is stronger. Moreira et al (2017) compared the previous GROMOS retrieval dataset to MLS between 2009 and 2016. Similar agreement was found in the middle stratosphere however quickly degrading at lower and higher altitudes.…”

Section: Profile Comparisonsmentioning

confidence: 99%

Harmonized retrieval of middle atmospheric ozone from two microwave radiometers in Switzerland

Sauvageat

Barras²,

Hocke³

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

Abstract. We present new harmonized ozone time series from two ground-based microwave radiometers in Switzerland: GROMOS and SOMORA. Both instruments measure hourly ozone profiles in the middle atmosphere (20–75 km) since more than two decades. As inconsistencies in long-term trends derived from these two instruments were detected, a harmonization project was initiated in 2019. The goal was to understand and reduce the discrepancies between the two data records. The harmonization has been completed for the data from 2009 until 2022 and has been successful at reducing the differences observed between both time series. It also explains the remaining differences between both instruments and flags their respective anomalous measurement periods in order to adapt their consideration for future trend computations. We describe the harmonization and the resulting time series in detail. We also highlight the improvements in the ozone retrievals with respect to the previous data processing. In the stratosphere and lower mesosphere, the seasonal ozone relative differences between both instruments are now within 10 % and show good correlations (R > 0.7) except for summertime. We also perform a comparison of these new data series against measurements from the satellite instruments Microwave Limb Sounder (MLS) and Solar Backscatter Ultraviolet Radiometer (SBUV) over Switzerland. Seasonal mean differences with MLS and SBUV are within 10 % in the stratosphere and lower mesosphere up to 60 km and increase rapidly above.

show abstract

“…The equatorial (2S) and mid-latitude (30S) profiles are rather similar but without the MMM layer (see Figure 5). Moreira et al [60] studied the annual variation in mesospheric ozone above Bern (Switzerland, 46.95N, 7.44E). The winter enhancement of nighttime mesospheric ozone was observed, indicating that the MMM layer during winter reaches northern mid-latitudes as well.…”

Section: Geographical Location Of the MMM Layermentioning

confidence: 99%

Ecologically Important Reactions and Phenomena in the Mesosphere between the Two Global Ozone Layers

Hänninen¹

2018

eer

View full text Add to dashboard Cite

Due to their buoyance, methane and water vapor (H2O(g)) ascend into the mesosphere where they are destroyed by chemical reactions or photolysis. In the mesosphere at 81 to 83 km, H2O(g) condenses to ice which then, due to the lack of buoyance, descends to 70 to 75 km where ice sublimates back to H2O(g). A mesospheric minicycle of water forms. In boreal summer evenings the ice layer is visually observable from the ground as noctilucent clouds (NLC). The middle mesospheric ozone maximum (MMM) forms in the wintertime at a height of 70 to 75 km. It is located between the mid-latitudes and somewhat north from the Arctic Circle, and symmetrically in the Southern Hemisphere. In the daytime solar radiation keeps the ozone concentration at a low level. During the civil and nautical twilight the intensity of the sun's rays decrease dramatically. Ozone gains from this decrease most. At high latitudes the solar radiation angle (θs) decreases more slowly than at the mid-latitudes. IR radiation has more time to photoexcite O2(1 Δg) and triplet state ozone (O3*). O2(1 Δg) maintains the ozone concentration and O3* spontaneously provides oxygen atoms. As a result, the amplitude of the MMM layer in terms of ozone concentration increases towards the high latitudes.

show abstract

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

Cited by 9 publications

References 25 publications

Ground-based ozone profiles over central Europe: incorporating anomalous observations into the analysis of stratospheric ozone trends

Ground-based ozone profiles over central Europe: incorporating anomalous observations into the analysis of stratospheric ozone trends

Harmonized retrieval of middle atmospheric ozone from two microwave radiometers in Switzerland

Ecologically Important Reactions and Phenomena in the Mesosphere between the Two Global Ozone Layers

Contact Info

Product

Resources

About