Scheel, H.E.

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Scheel, H. E.

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Ozone Trends at the Mountain SitesZugspitze and Wank (47 °N)H.E. ScheelKarlsruhe Institute of Technology (KIT)[formerly Forschungszentrum Karlsruhe]IMK-IFU (Germany)Tropospheric Ozone Changes WorkshopB ld 14 16 O t b 2009ou er , -  c o er Zugspitze: 47°N, 11°E, 2962 m asl, at the northern rim of the AlpsAnalysis of ozone data (1978 2008)     –  with respect to: Long-term trend  Seasonal variations I t f diff t t h impac  o  eren  a mosp er c conditionsFocus on differences between    earlier and more recent parts of the time seriesOverview on the O3 data structure at Zugspitze (half-hourly mean values, 1996 - 2000).By short term variations a range of about 110 ppb 110-is covered.80901006070b)4050  O3 (pp1020301996 1997 1998 1999 2000 20010O3 monthly mean values (1978 – 2008) together with regression curve and long-term trend component7080Zugspitze (2962 m)6050  O3 [ppb]3040Monthly meansO1978 1982 1986 1990 1994 1998 2002 2006 201020  Trend Regression curveYEARPart 1: 1978 - 1989 Part 2: 1990 - 2002 Part 3: 2003 - 2008Trend curves for the sites Zugspitze (2962 m) and Wank (1780 m)Comparisons with the neighbouring Wank summit: Smaller and partly negative      l       Avg: ZUG: 1.13 ppb yr-1 0.24 ppb yr-1growth rates during the 1990s, remarkab e agreement in the trend behaviourfrom 2000 onwards.- 0.55 ppb yr-1505560Trend Comparison4045ZUG3 [ppb]I t t  th t  3035  WNKO3 ns an aneous grow ra e= derivate of trend curve1978 1982 1986 1990 1994 1998 2002 2006 2010YEARPart 1: 1978 - 1989 Part 2: 1990 - 2002 Part 3: 2003 - 2008WNK: 0.98 ppb yr-1 0  ppb yr-1 - 0.79 ppb yr-1Results of modelling and emission inventories in the literature indicate relationships between NOx emission trends (increases / reductions) and surface ozone       levels.5560404550Trend Comparison[ppb]1978 1982 1986 1990 1994 1998 2002 2006 20103035 ZUG WNKO3 Strong increase in European NOx emissions between 1950 Reductions in emissions since the late 1980sYEARand 1980.Ref., e.g.: Vestreng et al. (2009), Evolution of NOx emissions in Europe with focus on road .transport control measures, Atmos. Chem. Phys., 9, 1503-1520.Average O3 growth rates [ppb yr-1] at 11-day temporal resolution: 1978 - 1989 (without 1982) and 1990 – 2002, & thl mon y meansAnnual meansDifference of growth rates, i.e. rate (1990 2002) -  minusrate (1978-1989).Filtering of Ozone DataBased on the parameters: ♦ relative humidity (RH), ♦ beryllium-7 (7Be),♦ carbon monoxide (CO) [available since 1990](1) Selection of air masses influenced from the lower stratosphere/upper troposphere:"RH < 60 % AND 7Be > 85th percentile of the annual data set"              (abbreviated 7Be(P85)/RH).(2) For dry air affected predominantly by the lower stratosphere/upper troposphere:Combined RH criterion  requesting: "RH < 60 % AND RH running minimum over 12 hours < 30 %" (abbreviated         RH60/30)(3) Relatively unpolluted air:   CO < 30-day running median of CO(4) Polluted air: CO > 30-day running median of COGrowth Rates for Different Atmospheric ConditionsCalculated from the slope of linear regression on selected data sets Growth rate comparison: 1978-1989 and 1990-2002Zugspitze: Ozone growth rates [ppb/yr] from linear regression on monthly means with 95%-confidence limits Periods 1978-1989 & 1990-2002  .    1.501.000.50ppb/yr]0.00[p-0.50All data night-time RH<60 7Be(P85)/RH 7Be(P65)/RH RH60/30Rate(78-89)Rate(90-02)1978-1989: Similar rates for different conditions1990-2002: Highest rates for air from lower stratosphere/upper troposphereGrowth rate comparison: 1978-1989 and 1990-2002Zugspitze: Ozone growth rates [ppb/yr] from linear regression on monthly means with 95%-confidence limits Periods 1978-1989 & 1990-2002  .    1.5018.1 8.6 13.1 10.6Contribution of selected condition [%]1.0023.0 8.8 14.2 14.70.50ppb/yr]0.00[p-0.50All data night-time RH<60 7Be(P85)/RH 7Be(P65)/RH RH60/30Rate(78-89)Rate(90-02)1978-1989: Similar rates for different conditions1990-2002: Highest rates for air from lower stratosphere/upper troposphereComparison of growth rate calculations (1990-2002):Monthly means & Annual meansZugspitze: Ozone growth rates (1990 - 2002) from linear regression on monthly and annual means with 95%-confidence limits0.801.00Proxy of background 0 400.60trend (?)0.20.[ppb/yr]Rate(MM)Rate(AnnM)-0.200.00All data 7Be(P85)/RH 7Be(P65)/RH RH60/30 Unpolluted Polluted-0.40Highest rates associated with "clean air" conditionsA different view on the ozone trendGrowth rates from seasonal percentiles: 5th, 25th, 50th, 75th, 95th1978-1989 & 1990-2002Winter = Dec, Jan, Feb; Summer = Jun, Jul, AugZugspitze, O3 growth rates1 80Zugspitze, O3 growth rates1.201.401.60.yr]Winter (1978-1989)Summer (1978-1989)0.200.400.60r]0.400.600.801.00Rate [ppb/y-0.200.00P5 P25 P50 P75 P95Rate [ppb/yrWinter (1990 2002)0.000.20P5 P25 P50 P75 P95-0.60-0.40  -Summer (1990-2002)1978 – 1989: Highest O3 increaseassociated with highest summer-timeconcentrations1990 – 2002: Strongest O3 decreaseassociated with highest summer-timeconcentrationsThe most recent development – from 6 years onlyGrowth rates from seasonal percentilesZ gspit e O3 gro th rates2003-2008: Winter = Dec, Jan, Feb;2004-2005 & 2007-2008: Summer = Jun, Jul, Augu z ,  w  1.000.000.50r]-0.50P5 P25 P50 P75 P95Rate [ppb/yr-1.50-1.00RWinter (2003-2008)Summer (04-05,07-08)-2.00Seasonal Variations from Different Data SetsAverage seasonal variations:All data 1990 – 2002, "unpolluted", "polluted"65605055(78-89)45O3 [ppb] 40all data (90-02)CO>30d_medCO<30d_med35JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DECAverage seasonal variations:all data 1990 – 2002, "unpolluted", "polluted"ll d t 2004 2005 2007 2008a  a a - , - ,2009 (Jan – Aug) Statistics of Data FlagsWhat does it indicate ?Temporal development of events flagged by the criteria7Be(P85)/RH and RH60/301) Annual number of events fulfilling the 7Be(P85)/RH criterion: Increase by         a factor of 1.23 from 1978 to 2005 (95% confidence level)Associated data coverage: Increase by a factor of 1.25 (90% c.l.) Average duration of events ≈ constant2) Annual number of events fulfilling the RH60/30 criterion: Increase by a factor of ≈ 2   Associated data coverage: Increase by a factor of ≈ 2.6 Average duration of events has increased (95% c.l.)Ratio of annual number of events: n(RH) / n(Be7)  significant increase (99% c.l.)   This means: RH60/30 events have become relatively more frequent than 7Be(P85)/RH events     .Ozone at Zugspitze (1978 – 2008)Summary The time series displays 3 different regimes:1978 – 1989, 1990 – 2002, 2003 – 2008 with different seasonal dependence of growth rates Part of the trend behaviour reflects the development of i iprecursor em ss ons Clean-air data filtering (1990 – 2002):Growth rates are above the all data value     -  Seasonal variations with pronounced spring maximum O3 in polluted air (1990 2002):    Rates smaller than the all-data caseSeasonal maximum shifted to mid-summer Indications of an increasing influence of upper tropospheric air masses on ozone at ZugspitzeAcknowledgementsThanks to all who contributed throughtechnical support and data processing,t f 7Bmeasuremen s o  e,supplementary data,trajectory calculations, discussions,financial support.Part of the Zugspitze study was a contribution to the          project ATMOFAST, funded by the German BMBF.From mid-1998 until March 2002 the in-situ ozone instrumentation at the Zugspitze summit was operated by the German Environment Agency (UBA).

Ozone trends at the mountain sites Zugspitze and Wank (47⁰N)

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Ozone trends at the mountain sites Zugspitze and Wank (47⁰N)

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