1. OHP ozone lidar time series, trends and comparison with nearby measurements
S. Godin-Beekmann1, A. Pazmiño1, F. Goutail1, S. Khaykin1, M.R. de Backer2, F. Jégou3, I. Petropavloskikh4
LATMOS/IPSL, UVSQ, CNRS, France
Université de Reims, Reims, France
LPC2E, Orléans, France
GMDL, NOAA, USA

2. Recent post 1998 trends Plan
Past changes in the vertical distribution of ozone, Part III:
Analysis and interpretation of trends
Harris et al., ACP, 2015
Trend model:
Seasonnal variation, QBO, ENSO, Solar cycle, stratospheric aerosols
Conclusions different from WMO 2014 ozone assesment

3. OHP Stratospheric Ozone Measurem
Ozone measurement records at OHP
OHP Stratospheric Ozone Measurem
Haute-Provence Observatory:
44°N, 6°E – part of NDACC Alpine station
Pioneer station for lidar measurements: temperature (since 1979), ozone, aerosols, water vapour, wind
Total ozone measurements:
Dobson spectrometer since September 1983
SAOZ UV-Visible spectrometer since January 1992
Stratospheric ozone vertical distribution
Stratospheric ozone lidar (since July 1985 – routine from 1986)
Ozone sondes: ECC since January 1991
Dobson Umkehr since September 1983

4. Total ozone trends at OHP
Multiple regression analysis
deseasonalized monthly ozone levels and multiple proxies; autocorrelation taken into account
Proxies:
QBO (30 & 10 hPa),
NAO index (Hurrell et al. 2003),
F10.7 cm solar flux
100 hPa eddy heat flux averaged over °N
aerosol optical depth at 550 nm
EESC or PWLT (piecewise linear trend with turning point at end of 1996)
e.g. Vyushin et al., 2007, Nair et al., 2013

5. Total ozone trends Similar results using PWLT and EESC
Influence of proxies:
Low ozone values mainly due to QBO west. phase, low heat flux and Pinatubo aerosols in the 1990s
(e.g. 1990, 1995, 1997, 2002)
Large anomalies: QBO east. phase, large heat flux, negative NAO index (e.g. 1986, 1987, 2009, 2010, 2014)
Mean annual total ozone PWL Trend :
Pre-1997: ± 0.26 DU/yr
Post-1997: 0.36 ± 0.83 DU/yr

6. Plan
Analysis of trends in ozone vertical distribution

7. Data sets used Plan Local measurements Ozone lidar (1986 – present)
Ozone sondes (1991 – present)
Umkehr (1983 – present)
Satellite measurements
SAGE II (1984 – 2004)
Aura MLS (2004 – present)
Vertical resolution
Ozone sondes (0.3 km), lidar (0.5 – 5 km), umkehr (~5 km in the mid stratosphere), SAGE II (~1 km), MLS (~3 km)
All data converted to ozone number density vs altitude using NCEP data above OHP

8. Drift analysis
Plan

9. Ozone profile anomalies
Plan
Ozone profile anomalies
uncorrected sondes
Ozone anomaly (%)
Relatively good agreement between time series, depending on altitude and time period. Need to use sondes correction factor. Geophysical pertubation of similar size as temporary instrumental artefacts

10. Anomalies comparison Plan
Comparison between SAGEII, Aura MLS and sondes anomalies with lidar anomalies
Altitude (km)
Monthly anomalies differences (%)

11. Regression results Plan
Regression model applied to average ozone monthly anomalies R2
Month

12. Ozone recovering trends from individual records
Ozone profile trends at OHP
Plan
Before 1997
After 1997
Ozone recovering trends from individual records
Mean anomalies

13. Comparison with nearby records
Plan
Comparison with nearby records
Ozone lidar at Hohenpeissenberg (1987 – present)
Microwave spectrometer at Bern (Switzerland)
Ozone anomaly (%)

14. Plan
Recovering trends

15. Plan
Conclusions
Unsignificant recovering trends in total ozone at OHP over the 1997 – 2015 period
Reasonably good agreement between individual time series
Temporary instrumental artefacts of similar size as geophysical signals in time series -> spurious trends depending on the time period of study
Generally significant recovering trend in ozone profile, with an average of ~1.7 %/decade and a range of about 3%/decade

16. Plan
Perspectives
Publication pour la NDACC special issue (31/03/2017):
Extension des résultats jusqu’à fin 2016.
Comparaison des séries temporelles avec les simulations (Reprobus, Slimcat(?), GMI model)
Comparaison des séries temporelles de lidar ozone (tropo et strato) avec mesures IASI - projet CNES.
Evaluation de la restitution du profil de température avec les voies non absorbées (355nm – 387 nm) (R. Wing) et étude de la corrélation avec l’ozone.
Evaluation de la restitution du profil d’ozone avec méthode d’estimation optimale (coopération avec Bob Sica de l’Université de Western Ontario).