scholarly journals Evolution of stratospheric ozone and water vapour time series studied with satellite measurements

2009 ◽  
Vol 9 (16) ◽  
pp. 6055-6075 ◽  
Author(s):  
A. Jones ◽  
J. Urban ◽  
D. P. Murtagh ◽  
P. Eriksson ◽  
S. Brohede ◽  
...  
Keyword(s):  
Time Series ◽  
Water Vapour ◽  
Stratospheric Ozone ◽  
Stratospheric Aerosol ◽  
Data Sets ◽  
Model Errors ◽  
Quasi Biennial Oscillation ◽  
Sigma Level ◽  
Scanning Imaging

Abstract. The long term evolution of stratospheric ozone and water vapour has been investigated by extending satellite time series to April 2008. For ozone, we examine monthly average ozone values from various satellite data sets for nine latitude and altitude bins covering 60° S to 60° N and 20–45 km and covering the time period of 1979–2008. Data are from the Stratospheric Aerosol and Gas Experiment (SAGE I+II), the HALogen Occultation Experiment (HALOE), the Solar BackscatterUltraViolet-2 (SBUV/2) instrument, the Sub-Millimetre Radiometer (SMR), the Optical Spectrograph InfraRed Imager System (OSIRIS), and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartograpY (SCIAMACHY). Monthly ozone anomalies are calculated by utilising a linear regression model, which also models the solar, quasi-biennial oscillation (QBO), and seasonal cycle contributions. Individual instrument ozone anomalies are combined producing an all instrument average. Assuming a turning point of 1997 and that the all instrument average is represented by good instrumental long term stability, the largest statistically significant ozone declines (at two sigma) from 1979–1997 are seen at the mid-latitudes between 35 and 45 km, namely −7.2%±0.9%/decade in the Northern Hemisphere and −7.1%±0.9%/in the Southern Hemisphere. Furthermore, for the period 1997 to 2008 we find that the same locations show the largest ozone recovery (+1.4% and +0.8%/decade respectively) compared to other global regions, although the estimated trend model errors indicate that the trend estimates are not significantly different from a zero trend at the 2 sigma level. An all instrument average is also constructed from water vapour anomalies during 1991–2008, using the SAGE II, HALOE, SMR, and the Microwave Limb Sounder (Aura/MLS) measurements. We report that the decrease in water vapour values after 2001 slows down around 2004–2005 in the lower tropical stratosphere (20–25 km) and has even shown signs of increasing until present. We show that a similar correlation is also seen with the temperature measured at 100 hPa during this same period.

scholarly journals Evolution of stratospheric ozone and water vapour time series studied with satellite measurements

2009 ◽  
Vol 9 (1) ◽  
pp. 1157-1209 ◽  
Author(s):  
A. Jones ◽  
J. Urban ◽  
D. P. Murtagh ◽  
P. Eriksson ◽  
S. Brohede ◽  
...  
Keyword(s):  
Time Series ◽  
Water Vapour ◽  
Stratospheric Ozone ◽  
Stratospheric Aerosol ◽  
Data Sets ◽  
Quasi Biennial Oscillation ◽  
Long Term Stability ◽  
Infrared Imager ◽  
Scanning Imaging

Abstract. The long term evolution of stratospheric ozone and water vapour has been investigated by extending satellite time series to April 2008. For ozone, we examine monthly average ozone values from various satellite data sets for nine latitude and altitude bins covering 60° S to 60° N and 20–45 km and covering the time period 1979–2008. Data are from the Stratospheric Aerosol and Gas Experiment (SAGE I+II), the HALogen Occultation Experiment (HALOE), the Solar BackscatterUltraViolet-2 (SBUV/2) instrument, the Sub-Millimetre Radiometer (SMR), the Optical Spectrograph InfraRed Imager System (OSIRIS), and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartograpY (SCIAMACHY). Monthly ozone anomalies are calculated by utilising a linear regression model, which also models the solar, quasi-biennial oscillation (QBO), and seasonal cycle contributions. Individual instrument ozone anomalies are combined producing a weighted all instrument average. Assuming a turning point of 1997 and that the all instrument average is represented by good instrumental long term stability, the largest statistically significant ozone declines from 1979–1997 are seen at the mid-latitudes between 35 and 45 km, namely −7.7%/decade in the Northern Hemisphere and −7.8%/decade in the Southern Hemisphere. For the period 1997 to 2008 we find that the southern mid-latitudes between 35 and 45 km show the largest ozone recovery (+3.4%/decade) compared to other global regions, although the estimated trend model error is of a similar magnitude (+2.1%/decade, at the 95% confidence level). An all instrument average is also constructed from water vapour anomalies during 1984–2008, using the SAGE II, HALOE, SMR, and the Microwave Limb Sounder (aura/MLS) measurements. We report that the decrease in water vapour values after 2001 slows down around 2004 in the lower tropical stratosphere (20–25 km), and has even shown signs of increasing values in upper stratospheric mid-latitudes. We show that a similar correlation is also seen with the temperature measured at 100 hPa during this same period.

scholarly journals Coherence of long-term stratospheric ozone vertical distribution time series used for the study of ozone recovery at a northern mid-latitude station

2011 ◽  
Vol 11 (10) ◽  
pp. 4957-4975 ◽  
Author(s):  
P. J. Nair ◽  
S. Godin-Beekmann ◽  
A. Pazmiño ◽  
A. Hauchecorne ◽  
G. Ancellet ◽  
...  
Keyword(s):  
Time Series ◽  
Stratospheric Ozone ◽  
Stratospheric Aerosol ◽  
Data Sets ◽  
Zero Bias ◽  
Lidar Measurements ◽  
Relative Differences ◽  
Difference Time

Abstract. The coherence of stratospheric ozone time series retrieved from various observational records is investigated at Haute-Provence Observatory (OHP–43.93° N, 5.71° E). The analysis is accomplished through the intercomparison of collocated ozone measurements of Light Detection and Ranging (lidar) with Solar Backscatter UltraViolet(/2) (SBUV(/2)), Stratospheric Aerosol and Gas Experiment II (SAGE~II), Halogen Occultation Experiment (HALOE), Microwave Limb Sounder (MLS) on Upper Atmosphere Research Satellite (UARS) and Aura and Global Ozone Monitoring by Occultation of Stars (GOMOS) satellite observations as well as with in situ ozonesondes and ground-based Umkehr measurements performed at OHP. A detailed statistical study of the relative differences of ozone observations over the whole stratosphere is performed to detect any specific drift in the data. On average, all instruments show their best agreement with lidar at 20–40 km, where deviations are within ±5 %. Discrepancies are somewhat higher below 20 and above 40 km. The agreement with SAGE II data is remarkable since average differences are within ±1 % at 17–41 km. In contrast, Umkehr data underestimate systematically the lidar measurements in the whole stratosphere with a near zero bias at 16–8 hPa (~30 km). Drifts are estimated using simple linear regression for the data sets analysed in this study, from the monthly averaged difference time series. The derived values are less than ±0.5 % yr−1 in the 20–40 km altitude range and most drifts are not significant at the 2σ level. We also discuss the possibilities of extending the SAGE II and HALOE data with the GOMOS and Aura MLS data in consideration with relative offsets and drifts since the combination of such data sets are likely to be used for the study of stratospheric ozone recovery in the future.

scholarly journals Coherence of long-term stratospheric ozone vertical distribution time series used for the study of ozone recovery at a northern mid-latitude station

2010 ◽  
Vol 10 (11) ◽  
pp. 28519-28564
Author(s):  
P. J. Nair ◽  
S. Godin-Beekmann ◽  
A. Pazmiño ◽  
A. Hauchecorne ◽  
G. Ancellet ◽  
...  
Keyword(s):  
Time Series ◽  
Stratospheric Ozone ◽  
Stratospheric Aerosol ◽  
Data Sets ◽  
Zero Bias ◽  
Lidar Measurements ◽  
Relative Differences ◽  
Difference Time

Abstract. The coherence of stratospheric ozone time series retrieved from various observational records is investigated at Haute–Provence Observatory (OHP–43.93° N, 5.71° E). The analysis is accomplished through the intercomparison of collocated ozone measurements of Light Detection and Ranging (lidar) with Solar Backscatter UltraViolet(/2) (SBUV(/2)), Stratospheric Aerosol and Gas Experiment II (SAGE II), Halogen Occultation Experiment (HALOE), Microwave Limb Sounder (MLS) on Upper Atmosphere Research Satellite (UARS) and Aura and Global Ozone Monitoring by Occultation of Stars (GOMOS) satellite observations as well as with in-situ ozonesondes and ground-based Umkehr measurements performed at OHP. A detailed statistical study of the relative differences of ozone observations is performed to detect any specific drifts in the data. On average, all instruments show their best agreement with lidar at 20–40 km, where deviations are within ±5%. Discrepancies are somewhat higher below 20 and above 40 km. The agreement with SAGE II data is remarkable since average differences are within ±1% at 17–41 km. In contrast, Umkehr data underestimate systematically the lidar measurements in the whole stratosphere albeit a near zero bias is observed at 16–8 hPa (~30 km). Drifts are estimated using simple linear regression for the long-term (more than 10 years long) data sets analysed in this study, from the monthly averaged difference time series. The derived values are less than ±0.5% yr−1 in the 20–40 km altitude range and most drifts are not significant at the 2σ level.

scholarly journals Merging of ozone profiles from SCIAMACHY, OMPS and SAGE II observations to study stratospheric ozone changes

2018 ◽  
Author(s):  
Carlo Arosio ◽  
Alexei Rozanov ◽  
Elizaveta Malinina ◽  
Mark Weber ◽  
John P. Burrows
Keyword(s):  
Time Series ◽  
Stratospheric Ozone ◽  
Multivariate Regression Analysis ◽  
Stratospheric Aerosol ◽  
Montreal Protocol ◽  
Data Sets ◽  
Data Set ◽  
Vertical Range ◽  
Scanning Imaging ◽  
Ozone Depleting Substances

Abstract. This paper presents vertically and zonally resolved merged ozone time series from limb measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) and the Ozone Mapping and Profiler Suite (OMPS). In addition, we present the merging of the latter two data sets with zonally averaged profiles from the Stratospheric Aerosol and Gas Experiment (SAGE) II. The retrieval of ozone profiles from SCIAMACHY and OMPS is performed at the University of Bremen. Within the merging procedure of these two time series we use data from the Microwave Limb Sounder (MLS) as a transfer function and we follow two approaches: (1) a standard method involving the calculation of deseasonalized anomalies and (2) a plain-debiasing approach, generally not considered in previous similar studies, which preserves the seasonal cycles of each instrument. We find a good correlation and no significant drifts between the merged and MLS time series. Using the merged data set, we apply a multivariate regression analysis to study ozone changes over the 2003–2018 period in the 20–50 km vertical range. Exploiting the high horizontal sampling of the instruments, we investigate not only the zonally averaged field but also the longitudinally resolved long-term ozone variations, finding a remarkable variability, especially at mid- and high-latitudes. Significant positive linear trends of about 2–4 % per decade were identified in the upper stratosphere between 38 and 45 km at mid-latitudes. This is in agreement with the predicted recovery of upper stratospheric ozone, which is attributed both to the adoption of measures to limit the release of halogen-containing ozone-depleting substances included in the Montreal protocol and to the increasing concentration of greenhouse gases. In the tropical stratosphere below 25 km negative but non-significant trends were found. We compare our results with similar previous studies and with short-term trends calculated over the SCIAMACHY period: while a general agreement is found, some discrepancies are seen in the tropical mid-stratosphere. Regarding the merging of SAGE II with SCIAMACHY and OMPS, zonal mean anomalies are taken into consideration and ozone trends after and before 1997 are shown. Negative trends above 30 km are found for the 1985–1997 period, with a peak of −6 % per decade at mid-latitudes, in agreement with previous studies. The increase of ozone concentration in the upper stratosphere is confirmed considering the 1998–2018 period. Trends in the middle and lower tropical stratosphere are found to be non-significant.

scholarly journals Analysis of global water vapour trends from satellite measurements in the visible spectral range

2007 ◽  
Vol 7 (4) ◽  
pp. 11761-11796 ◽  
Author(s):  
S. Mieruch ◽  
S. Noël ◽  
H. Bovensmann ◽  
J. P. Burrows
Keyword(s):  
Time Series ◽  
Water Vapour ◽  
Statistical Significance ◽  
Visible Spectral Range ◽  
Optical Absorption Spectroscopy ◽  
Data Set ◽  
Factors Affecting ◽  
Scanning Imaging ◽  
Global Water

Abstract. Global water vapour total column amounts have been retrieved from spectral data provided by the Global Ozone Monitoring Experiment (GOME) flying on ERS-2, which was launched in April 1995, and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) onboard ENVISAT launched in March 2002. For this purpose the Air Mass Corrected Differential Optical Absorption Spectroscopy (AMC-DOAS) approach has been used. The combination of the data from both instruments provides us with a long-term global data set spanning more than 11 years with the potential of extension up to 2020 by GOME-2 data, on Metop. Using linear and non-linear methods from time series analysis and standard statistics the trends of H2O contents and their errors have been calculated. In this study, factors affecting the trend such as the length of the time series, the magnitude of the variability of the noise, and the autocorrelation of the noise are investigated. Special emphasis has been placed on the calculation of the statistical significance of the observed trends, which reveal significant local changes of water vapour columns distributed over the whole globe.

scholarly journals Merging of ozone profiles from SCIAMACHY, OMPS and SAGE II observations to study stratospheric ozone changes

2019 ◽  
Vol 12 (4) ◽  
pp. 2423-2444
Author(s):  
Carlo Arosio ◽  
Alexei Rozanov ◽  
Elizaveta Malinina ◽  
Mark Weber ◽  
John P. Burrows
Keyword(s):  
Time Series ◽  
Stratospheric Ozone ◽  
Multivariate Regression Analysis ◽  
Stratospheric Aerosol ◽  
Montreal Protocol ◽  
Inversion Algorithm ◽  
Data Set ◽  
Large Variability ◽  
Stratospheric Temperature

Abstract. This paper presents vertically and zonally resolved merged ozone time series from limb measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) and the Ozone Mapping and Profiler Suite (OMPS) Limb Profiler (LP). In addition, we present the merging of the latter two data sets with zonally averaged profiles from Stratospheric Aerosol and Gas Experiment (SAGE) II. The retrieval of ozone profiles from SCIAMACHY and OMPS-LP is performed using an inversion algorithm developed at the University of Bremen. To optimize the merging of these two time series, we use data from the Microwave Limb Sounder (MLS) as a transfer function and we follow two approaches: (1) a conventional method involving the calculation of deseasonalized anomalies and (2) a “plain-debiasing” approach, generally not considered in previous similar studies, which preserves the seasonal cycles of each instrument. We find a good correlation and no significant drifts between the merged and MLS time series. Using the merged data set from both approaches, we apply a multivariate regression analysis to study ozone changes in the 20–50 km range over the 2003–2018 period. Exploiting the dense horizontal sampling of the instruments, we investigate not only the zonally averaged field, but also the longitudinally resolved long-term ozone variations, finding an unexpected and large variability, especially at mid and high latitudes, with variations of up to 3 %–5 % per decade at altitudes around 40 km. Significant positive linear trends of about 2 %–4 % per decade were identified in the upper stratosphere between altitudes of 38 and 45 km at mid latitudes. This is in agreement with the predicted recovery of upper stratospheric ozone, which is attributed to both the adoption of measures to limit the release of halogen-containing ozone-depleting substances (Montreal Protocol) and the decrease in stratospheric temperature resulting from the increasing concentration of greenhouse gases. In the tropical stratosphere below 25 km negative but non-significant trends were found. We compare our results with previous studies and with short-term trends calculated over the SCIAMACHY period (2002–2012). While generally a good agreement is found, some discrepancies are seen in the tropical mid stratosphere. Regarding the merging of SAGE II with SCIAMACHY and OMPS-LP, zonal mean anomalies are taken into consideration and ozone trends before and after 1997 are calculated. Negative trends above 30 km are found for the 1985–1997 period, with a peak of −6 % per decade at mid latitudes, in agreement with previous studies. The increase in ozone concentration in the upper stratosphere is confirmed over the 1998–2018 period. Trends in the tropical stratosphere at 30–35 km show an interesting behavior: over the 1998–2018 period a negligible trend is found. However, between 2004 and 2011 a negative long-term change is detected followed by a positive change between 2012 and 2018. We attribute this behavior to dynamical changes in the tropical middle stratosphere.

scholarly journals Analysis of HCl and ClO time series in the upper stratosphere using satellite data sets

2010 ◽  
Vol 10 (4) ◽  
pp. 8623-8655
Author(s):  
A. Jones ◽  
J. Urban ◽  
D. P. Murtagh ◽  
C. Sanchez ◽  
K. A. Walker ◽  
...  
Keyword(s):  
Time Series ◽  
Satellite Data ◽  
Atmospheric Chemistry ◽  
Montreal Protocol ◽  
Data Sets ◽  
Sigma Level ◽  
Chlorine Monoxide ◽  
The Tropics ◽  
Chemistry Experiment

Abstract. Previous analyses of satellite and ground-based measurements of hydrogen chloride (HCl) and chlorine monoxide (ClO) have suggested that total inorganic chlorine in the upper stratosphere is on the decline. We create HCl and ClO time series using satellite data sets with the intension of extending them to beyond November 2008 so that an update can be made on the long term evolution of these two species. We use the HALogen Occultation Experiment (HALOE) and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) data for the HCl analysis, and the Odin Sub-Millimetre Radiometer (SMR) and the Aura Microwave Limb Sounder (Aura-MLS) measurements for the study of ClO. Altitudes between 35 and 45 km and three latitude bands between 60° S–60° N for HCl, and 20° S–20° N for ClO are studied. HCl shows values to be reducing from peak 1997 values by −4.4% in the tropics and between −6.4% to −6.7% per decade in the mid-latitudes. Trend values are significantly different from a zero trend at the 2 sigma level. ClO is decreasing in the tropics by −7.1% ± 7.8%/decade based on measurements made from December 2001. As both of these species contribute most to the chlorine budget at these altitudes then HCl and ClO should decrease at similar rates. The results found here confirm how effective the 1987 Montreal protocol objectives and its amendments have been in reducing the total amount of inorganic chlorine.

scholarly journals Trend analysis of the 20 years time series of stratospheric ozone profiles observed by the GROMOS microwave radiometer at Bern

2015 ◽  
Vol 15 (12) ◽  
pp. 16371-16400
Author(s):  
L. Moreira ◽  
K. Hocke ◽  
E. Eckert ◽  
T. von Clarmann ◽  
N. Kämpfer
Keyword(s):  
Time Series ◽  
Trend Analysis ◽  
Southern Oscillation ◽  
Stratospheric Ozone ◽  
Microwave Radiometer ◽  
Atmospheric Composition ◽  
Quasi Biennial Oscillation ◽  
Ozone Trend ◽  
Long Term Trend

Abstract. The ozone radiometer GROMOS (GROund-based Millimeterwave Ozone Spectrometer) performs continuous observations of stratospheric ozone profiles since 1994 above Bern, Switzerland. GROMOS is part of the Network for the Detection of Atmospheric Composition Change (NDACC). From November 1994 to October 2011, the ozone line spectra were measured by a filter bench (FB). In July 2009, a Fast-Fourier-Transform spectrometer (FFTS) has been added as backend to GROMOS. The new FFTS and the original FB measured in parallel for over two years. The ozone profiles retrieved separately from the ozone line spectra of FB and FFTS agree within 5 % at pressure levels from 30 to 0.5 hPa, from October 2009 to August 2011. A careful harmonisation of both time series has been carried out by taking the FFTS as the reference instrument for the FB. This enables us to assess the long-term trend derived from more than 20 years of stratospheric ozone observations at Bern. The trend analysis has been performed by using a robust multilinear parametric trend model which includes a linear term, the solar variability, the El Niño–Southern Oscillation (ENSO) index, the quasi-biennial oscillation (QBO), the annual and semi-annual oscillation and several harmonics with period lengths between 3 and 24 months. Over the last years, some experimental and modelling trend studies have shown that the stratospheric ozone trend is levelling off or even turning positive. With our observed ozone profiles, we are able to support this statement by reporting a statistically significant trend of +3.14 % decade-1 at 4.36 hPa, covering the period from January 1997 to January 2015, above Bern. Additionally, we have estimated a negative trend over this period of −3.94 % decade-1 at 0.2 hPa.

scholarly journals Trend analysis of the 20-year time series of stratospheric ozone profiles observed by the GROMOS microwave radiometer at Bern

2015 ◽  
Vol 15 (19) ◽  
pp. 10999-11009 ◽  
Author(s):  
L. Moreira ◽  
K. Hocke ◽  
E. Eckert ◽  
T. von Clarmann ◽  
N. Kämpfer
Keyword(s):  
Time Series ◽  
Trend Analysis ◽  
Southern Oscillation ◽  
Stratospheric Ozone ◽  
Microwave Radiometer ◽  
Atmospheric Composition ◽  
Quasi Biennial Oscillation ◽  
Ozone Trend ◽  
Long Term Trend

Abstract. The ozone radiometer GROMOS (GROund-based Millimeter-wave Ozone Spectrometer) has been performing continuous observations of stratospheric ozone profiles since 1994 above Bern, Switzerland (46.95° N, 7.44° E, 577 m). GROMOS is part of the Network for the Detection of Atmospheric Composition Change (NDACC). From November 1994 to October 2011, the ozone line spectra were measured by a filter bench (FB). In July 2009, a fast Fourier transform spectrometer (FFTS) was added as a back end to GROMOS. The new FFTS and the original FB measured in parallel for over 2 years. The ozone profiles retrieved separately from the ozone line spectra of FB and FFTS agree within 5 % at pressure levels from 30 to 0.5 hPa, from October 2009 to August 2011. A careful harmonisation of both time series has been carried out by taking the FFTS as the reference instrument for the FB. This enables us to assess the long-term trend derived from stratospheric ozone observations at Bern. The trend analysis was performed by using a robust multilinear parametric trend model which includes a linear term, the solar variability, the El Niño–Southern Oscillation (ENSO) index, the quasi-biennial oscillation (QBO), the annual and semi-annual oscillation and several harmonics with period lengths between 3 and 24 months. Over the last years, some experimental and modelling trend studies have shown that the stratospheric ozone trend is levelling off or even turning positive. With our observed ozone profiles, we are able to support this statement by reporting a statistically significant trend of +3.14 % decade−1 at 4.36 hPa (37.76 km), covering the period from January 1997 to January 2015, above Bern. Additionally, we have estimated a negative trend over this period of −3.94 % decade−1 at 0.2 hPa (59 km).

scholarly journals Stratospheric Extinction Profiles from SCIAMACHY Solar Occultation

2020 ◽  
Author(s):  
Stefan Noël ◽  
Klaus Bramstedt ◽  
Alexei Rozanov ◽  
Elizaveta Malinina ◽  
Heinrich Bovensmann ◽  
...  
Keyword(s):  
Time Series ◽  
Volcanic Eruptions ◽  
Stratospheric Aerosol ◽  
Optical Absorption Spectroscopy ◽  
Atmospheric Effects ◽  
Aerosol Extinction ◽  
Radiometric Calibration ◽  
Quasi Biennial Oscillation ◽  
Solar Occultation ◽  
Scanning Imaging

Abstract. The SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric CHartographY) instrument on ENVISAT provided between August 2002 and April 2012 measurements of solar and Earthshine spectra from the UV to the SWIR spectral region in multiple viewing geometries. We present a new approach to derive stratospheric aerosol extinction profiles from SCIAMACHY solar occultation measurements based on an onion peeling method similar to the Onion Peeling DOAS (Differential Optical Absorption Spectroscopy) retrieval, which has already been successfully used for the derivation of greenhouse gas profiles. Since the retrieval of aerosol extinction requires as input measured transmissions in absolute units, an improved radiometric calibration of the SCIAMACHY solar occultation measurements has been developed, which considers various instrumental and atmospheric effects specific to solar occultation. The extinction retrieval can in principle be applied to all wavelengths measured by SCIAMACHY. As a first application, we show results for 452 nm, 525 nm and 750 nm. The whole SCIAMACHY solar occultation time series has been processed, covering a latitudinal range of about 50–70° N. Reasonable extinctions are derived between about 15 and 30 km with typically larger uncertainties at higher altitudes due to decreasing extinction. Comparisons with collocated SAGE~II and SCIAMACHY limb aerosol data products revealed a good agreement with essentially no mean bias. However, depending on altitude differences of up to ± 20–30 % to SAGE II at 452 nm and 525 nm are observed. These differences are mainly caused by systematic vertical oscillations in the SCIAMACHY occultation data. The agreement with SCIAMACHY limb data is even better (typically within 5–10 % between 17 and 27 km). Major volcanic eruptions as well as occurrences of PSCs can be identified in the time series of extinction data and related anomalies. Influence of the Quasi-Biennial-Oscillation (QBO) are visible above 25 km. Estimated linear changes of extinction between 2003 and 2011 reach 20–30 % per year at 15 km, mainly because all relevant volcanic eruptions (above 50° N) occurred after 2006.

Sign in / Sign up

Export Citation Format

Share Document