Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.mao.kiev.ua/lao/presentation/staehelin_Is%20Ozone%20Recovering_Kiev%20SSch08.pdf Äàòà èçìåíåíèÿ: Wed Sep 24 17:21:53 2008 Äàòà èíäåêñèðîâàíèÿ: Tue Oct 2 06:17:40 2012 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: þæíàÿ àòëàíòè÷åñêàÿ àíîìàëèÿ

Is the ozone layer recovering ?
Johannes Staehelin
Institute for Atmospheric and Climate Atmospheric Science (IACETH), Swiss Federal Institute of Technology ZÝrich (ETHZ) UniversitÄtstrasse 16 CH-8092 ZÝrich, Switzerland email:Johannes.Staehelin@env.ethz.ch


1. Introduction
Measurements of ozone sondes of Payerne of Payerne (Switzerland). Black: 1970; red: 1980; green: 1990; blue: 2000

UV-B radiation

Greenhouse gas Air pollution


Swiss long-term ozone measurements long (MeteoSwiss since 1988)
1. Longest total ozone series of the world (Dobson total world spectrophotomery), homogenised 2. First Umkehr measurements (1930), continuous First (1930) measurements since 1956 3. Ozone sonde measurements since 1969 Ozone since (Payerne, Swiss Plateau)


Short history: 1970s history:
Anthropogenic stratospheric ozone depletion ozone (since early 1970s): Johnston (1971) Crutzen: · H. Johnston (1971), P. Crutzen: Ozone depletion by Super Sonic Transport (NOx) (?) · R. Stolarski, R.J. Cicerone (1974): Ozone Stolarski Ozone depletion by Chlorine radicals · M.J. Molina, S. Rowland (1974): Ozone Rowland Ozone depletion by CFCs (Ozone Depleting Substances (ODS): CFCs, halones, HFCFCs)


Surprise: Farman et al., 1985:
Descovery of Antarctic Ozone hole


Second part of 1980s
· 1988: Explanation of ozone hole by (anthropogenic) CFCs (halones) (heterogeneous chemistry) · 1988: Publication of International Ozone Trend Panel Report: Significant decrease in (winter) ozone at Northern midlatitudes (multiple regression analysis)


2. Global Regulation Global Regulation
· · · · 1985: Vienna Convention 1987: Montreal Protocol Several amendments and adjustments Quantity for (chemical) ozone depletion of ODS: EESC (Equivalent Effective qu ect Stratospheric Chlorine): Weighting over release and ozone depletion of individual ODS


EESC for mid-latitudes
http//:www.wmo.ch/web/arep/reports/ozone_2002/q&as.pdf, Seite Q.29

1980

1990

2000

2010

2020

2030

2040

2050

2060

2070

2080

2090

2100


3. Problem of documentation of ozone shield recovery
· Illustration by the total ozone series of Arosa: started in 1926 and continued since 1988 by MeteoSwiss: · Problem: Attribution of ozone evolution to individual processes (in addition to EESC) (in


Emission of ODS

EESC

Arosa Series


Further processes affecting mid-latitude ozone - Violent Volcanic eruptions (Pinatubo, June 1991) eruptions
- (Long-term) climate Variability: Strong correlation between (NAO(AO index and winter total ozone values at Arosa (Appenzeller et al., 2000, updated by J. MÄder), et al MÄder) Brewer Dobson Circ., polar ozone depletion


4. CATO ozone data sets ozone
CATO (Candidoz Assimilated Three-dimensional Ozone) Assimilated Three Ozone) (EU-project: CANDIDOZ: Chemical and Dynamical Influences on Decadal Ozone Change): Principle: · Measurements: Satellite total ozone data (since 1979) of NIWA data set (G. Bodeker): Composite of different satellite total ozone measurements normalized by total ground-based Dobson measurements · Assimilation technique: Kalman filtering · ECMWF (ERA-40) for PV at 16 pot. temp. levels · Tropospheric ozone residual susbstracted · Assimilation technique (PV) not suitable for upper stratospheric ozone: In one version satellite (SBUV) measurements used (see Brunner et al., J. Geophys Res., 2006)


CATO based on equivalent latitude/theta coordinates

A = 2 p (1 ­ sin fE) in spherical radian sin


Reconstruction method
Vertical column in equivalent latitude ­ space
Advection from low latitudes tit

vertical profile along equivalent latitudes

Advection from high latitudes

P = tropospheric residual <320 K

(, ) = (, ) + a d (- p ) (eq (,, ), )

0




5. Multiple regression analysis of CATO
Multiple linear regression model Yt = a + b (t) + N cj Xj(t) + e(t) t: number of month since start of record (t=1: January 1979) Yt: Monthly mean total ozone (or ozone partial pressure) a: seasonally varying intercept (offset) of ozone time series b: Trend term:Two hockey stick method (or EESC: Equivalent effective stratospheric chlorine) ci Xj(t): time series of expl. Var. (j= 1,N), (seasonally) var. coef e(t): residual variations (not described by model) a,b,c: depend on month of year, described by 12-month and 6-month harmonic series: cj(t) = cj(1) + 2 (cj,2k cos(2pkt/12) + cj,2k+1 sin(2pkt/12))


Used explanatory variables: variables:
EESC QBO10 QBO30 SOLAR Volcanic aerosols EPfl., N EPfl., S Vo Vol. pol. str. Cl., N Cl Vol. pol. str. Cl., S


Contribution of QBO(30hPa) and QBO(10hPa) to total ozone variabiability (funct. of season and equiv. latitude): Regression of season latitude): Regression coefficients multiplied by 1 of each proxy time series and then divided by 1979-2004 mean ozone distribution (% change in tot. O3 for 1 increase in proxy)


Annual average contribution to variability in ozone partial

pressure (altitude/equivalent latitude) (% change in ozone concentration for 1 increase in proxy)


Sequence of hemispheric EP-flux on global stratospheric ozone distribution


"Turn-around": Two hockey stick (Reinsel et al., 2005)


Mathematical description (Reinsel et al.)
Yt = µ + St + 1X1t + 2X2t + .... iZi,t .. + N
t: month (1, ..,T), period: 1978-2004 Yt: Monthly mean total ozone; µ : baseline constant mean ozone; constant St: Seasonal component (linear fit of sin/cos functions)
t

effect of ODS 2: change: linear additional upward trend, starting from 1996: effect of Montreal Protocol
Nt = Nt-1 + : autoregressive noise term; : independent random variables

1: linear (decreasing) trend, beginning at t=0:


Key results (1979-2004) (a)-(c): Changes in ; (d)-(f): upward trend


Conclusions from Brunner et al., ACP, 2006
· Equivalent latitude coordinates partially compensate for short term variabilty · Polar ozone depletion can not be separated from changes in Brewer Dobson circulation · Results regarding "recovery" depends on used explanatory variables variables · Using data until 2004: Only marginal sign of effect of Montreal Protocol regulation ff ti


Antartic ozone hole http://www.wmo.int/web/arep/gawozobull06.html // No indication of recovery: Extent of Antartic ozone depletion depends on meterological cond.


6. Conclusions Conclusions
· Record low values in 1992, increase since 1993: mainly attributable to Pinatubo eruption (1991) and (long-term) climate variability, etc. · No signs of revovery of Antartic ozone (in agreement with expectation) · Attribution of miladtitudinal changes to processes (Montreal Protocol (1987) vs. others) still challening · Continuation of high quality ground-based and satellite ozone measurements important important


7. Expectation
(Executive Summary, Scientific Assessm. of Ozone Depletion: 2006, WMO/UNEP, 18. 8. 2006
(http://www.wmo.int/web/arep/reports/ozone_2006/exec_sum_18aug.pdf ) (a) Produktion of ODS (black: CFCs and halones; grey: HCFCs (used as replacement) Effect of ODS on midlatitudinal stratospheric ozone (EESC) Ozone changes 60oS60oN (black: (black: Measurements; grey: numerical modles) Effect of ozone depletion on erythemal UV (grey according (c), (c), hattched: including additional processes)

(b)

(c)

(d)


(Possible) future development
· Montreal Protocol effective to reduce (anthropogenic) ODS emissions · Recovery of global ozone layer expected · Future challenges: Effect of climate change on stratospheric ozone · "Super recovery" caused by stratospheric temperature decrease ? · Intensification of Brewer-Dobson circulation ? · Increased transport of stratospheric ozone to troposphere ? Effect on tropospheric ozone budget ?