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United States of America National Report on Surface-
Based Ozone Research
Seventh WMO/UNEP Ozone Research Managers Meeting
Geneva, Switzerland18-21 May, 2008
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US AGENCIES CONTRIBUTING• National Aeronautics & Space Administration (NASA)• National Oceanic & Atmospheric Administration (NOAA)• National Science Foundation (NSF)• Department of Agriculture (USDA)• Environmental Protection Agency (EPA)
SURFACE-BASED NETWORKS• Dobson Ozone Spectrophotometer Network• Ozonesonde Networks (including SHADOZ)• Network for the Detection of Atmospheric Composition Change
(NDACC)• Advanced Global Atmospheric Gases Experiment (AGAGE)
Network• ESRL Global Monitoring Division Ozone-Depleting Gas Network• Ultraviolet Radiation Networks
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OBSERVATIONAL ACTIVITIES OZONE
Dobson Ozone Spectrophotometers (column and umkehr profiles - Part of GAW) – 16 global instruments plus the WMO World Standard instrument
UV-Multi Filter Shadowband Radiometer (column) – 32 US, 2 Canadian, 1 New Zealand
Brewer Spectrometer Network – 6 US Instruments Ozonesondes (profile) – 10 global sites plus additional
near-annual balloon campaigns Miscellaneous Remote Profile Sensors - LIDAR,
Microwave Radiometer, FTIR
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OBSERVATIONAL ACTIVITIESOzone-Relevant Gases and Variables
Aircraft and Balloon-borne – H2O, CFC’s, HCFC’s, HFC’s, CH3CCl3, CH3Br, CH3Cl
Surface – Global measurements of 25 ozone-depleting gases for determination of equivalent effective chlorine (EECl)
UV Visible spectrometers – NO2, BrO, OClO
FTIR spectrometers – HCl, HF, HNO3, ClONO2, NO
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OBSERVATIONAL ACTIVITIESUV
BROADBAND & FILTER INSTRUMENTS: SURFRAD Network – 7 sites ESRL Network – Boulder and Mauna Loa (in conjunction with
spectroradiometers) USDA UVB Monitoring Program – 34 sites
SPECTRORADIOMETERS: SURFRAD UV spectroradiometers at Table Mountain NDACC spectroradiometers at Mauna Loa and Boulder (in
collaboration with NIWA-New Zealand) NSF UV Monitoring Network - spectroradiometers at 7 sites,
mainly in the polar regions ESRL/EPA Brewer Mark IV spectrometers at 6 US sites
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SIGNIFICANT RESULTS
1. CONTRIBUTIONS TO OZONE ASSESSMENTS
2. OZONE LOSS LINKED TO ANTARCTIC CLIMATE CHANGE
3. OZONE-DEPLETING GAS OBSERVATIONS
4. DOBSON TOTAL OZONE TRENDS
5. OZONE HOLE TRENDS AT SOUTH POLE
6. RECENT INCREASES IN HCFCs
7. CLIMATE BENEFITS OF THE MONTREAL PROTOCOL
8. RECENT AIRBORNE MEASUREMENTS OF TROPICAL
BROMINE GASES
9. EVALUATING ODSs IN THE LABORATORY
10.UV RADIATION TRENDS
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Tropospheric Organic Chlorine
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Long-Lived Halocarbons Contributing to Equivalent Effective Cl
490
515
540
pp
t CFC-12
240
250
260
270
pp
t CFC-11
0
40
80
120
160
200
1990 1995 2000 2005
pp
t
CH3CCl3
HCFC-22
CCl4
CFC-113
0
5
10
15
20
pp
t
HCFC-142b
HCFC-141b
H-1211
H-1301
CH3Br
2.8
2.9
3.0
3.1
3.2
1990 1995 2000 2005
pp
b
Global EECl [Cl + (Br*60)]
Down11% from
peak
ESRL
9
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
1960 1980 2000 2020 2040 2060 2080Year (sample date + 6)
EE
SC
(p
pt)
ESRL Data
A1 (WMO 2006)
EESC in1980
Past Data
1980 level
Equivalent Effective Stratospheric Chlorine - Antarctica
ODGI2007 = 86
The Ozone Depleting Gas Index (ODGI)
ODGIRecovery = 0
ODGIMAX = 100 (1994)
HCFCs go away?
NOAA Ozone Depleting Gas Index
1990 1992 1994 1996 1998 2000 2002 2004 2006 2008
OD
GI
70
75
80
85
90
95
100
AntarcticMid-Latitudes
ESRL
EESC Observations
ProjectionWMO 2006
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Dobson Ozone Trends – A New Look
Dobson Ozone Trends
Harris, J.M., S.J. Oltmans, P.P. Tans, R.D. Evans, and D.L. Quincy, Geophys. Res. Lett. 28, 4535, 2001 (updated)
Smooth trend curves of monthly ozone values from selected Dobson stations (South Pole, continental US, and the tropics) are shown. Changes represented by the growth rate determined from differentiating these trend curves is an instantaneous measure of the rate of change of stratospheric ozone and thus represents various aspects of ozone layer recovery.
ESRL
No attempt to remove possible Pinatubo effects has been made
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Continental U.S. Total Column Ozone Growth Rate Instantaneous growth rate curve (± 2 SD) found from
differentiating the trend curve
Average growthrate 1968-1995:-2.16 %/decade
Average growthrate 1996-2007:+1.73 %/decade
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South Pole Total Column Ozone Growth Rate Instantaneous growth rate curve (± 2 SD) found from
differentiating the trend curve
Average growthrate 1968-1995:-11.1 %/decade
Average growthrate 1996-2007:-1.38 %/decade
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0
5
10
15
20
25
30
35
40
0 5 10 15
OZONE (millipascals)
AL
TIT
UD
E (
km
)
Jul-Aug AVG 268 DU 133 DU
OCT 09 93 DU 4 DU
TOTAL OZONE 12-20 Column
14 – 21 km total depletion region
2006 Antarctic Ozone Hole
OMI Satellite Measurements – Sept. 24, 2006
South Pole Balloon-borne MeasurementsOctober 9, 2006
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South Pole 14-21 km Column Ozone
1985 1990 1995 2000 2005 2010
Do
bso
n U
nit
s (D
U)
0
50
100
150
200
Beginningof recovery?
ProbablyNot
South Pole 14-21 km Column OzoneFrom Balloon Ozonesondes
ESRL
~1500 Balloon Flights
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South Pole October Ozone vs Temperature - 30 hPa
Temperature (C)
-90 -80 -70 -60 -50 -40 -30 -20
Ozo
ne
Mix
ing
Rat
io (
pp
mv)
0.1
1
10
1966-1972
South Pole October Ozone vs Temperature - 30 hPa
Temperature (C)
-90 -80 -70 -60 -50 -40 -30 -20
Ozo
ne
Mix
ing
Rat
io (
pp
mv)
0.1
1
10
1966-19721986-1989
South Pole October Ozone vs Temperature - 30 hPa
Temperature (C)
-90 -80 -70 -60 -50 -40 -30 -20
Ozo
ne
Mix
ing
Rat
io (
pp
mv)
0.1
1
10
1966-19721986-19891990-2004
South Pole October Ozone vs Temperature - 30 hPa
Temperature (C)
-90 -80 -70 -60 -50 -40 -30 -20
Ozo
ne
Mix
ing
Rat
io (
pp
mv)
0.1
1
10
1966-19721986-19891990-20042005-2007
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Recent Changes in HCFCs
ESRL
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Ozone-Depleting Gases also Affect Climate
CH4
N2O
CFCs
CH4
N2O
CFCsCCl4, CH3CCl3
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Methyl BromideHalon 1211Halon 1301
Halon 2402DibromomethaneOther Short-lived Org Br.
47%
24%
17%
5.2%
5.2%2.3%
Methyl BromideHalon 1211Halon 1301Halon 2402
DibromomethaneBromoformOther Short-lived Org Br.
31%
17%
13%
4.1%
12%
20%
2.9%
Methyl BromideHalon 1211Halon 1301Halon 2402
DibromethaneBromoformOther Short-lived Org Br.
38%
21%
15%
5.4%
9.4%
8.9%2%
0 -1 km
~ 17 km
4 - 8 kmMeBr=31%Halons=34%S.Lived=35%
MeBr=38%Halons=41%S.Lived=20%
MeBr=47%Halons=46%S.Lived=7.5%
Recent Airborne measurements define composition and distribution of organic bromine source gases in the tropical atmosphere
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Tak
en fr
om IP
CC
Spe
cial
Rep
ort (
2005
)
Montreal ProtocolKyoto Protocol
Evaluating Proposed Substitutes for ODSs
Evaluation of the environmental impact of a compound from production to end-of-life. Laboratory studies are used to evaluate and quantify atmospheric removal, climate impact, and degradation products.
DegradationDeposition
What is a Good Substitute ? Zero ODP Short Atm. Lifetime Low GWP Minimal Impact of Degradation Products
ESRL
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Preliminary analysis at eight sites shows changes in annual UV-B irradiance ranged from +6% to +14% over most of the US (orange bars) for the 10 year period 1994 to 2004. Purple bars show monthly variability.
USDA UV-B Monitoring and Research Program
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Mauna Loa Observatory, Hawaii
Boulder, Colorado
UV Monitoring
Local noon erythemal radiation calculated from UV spectroradiometers (1 nm resolution) at Mauna Loa, Hawaii and Boulder, Colorado
and NIWAESRL
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SUMMARY
• Measurements of ozone-depleting gases show a decline in total ozone-depleting potential (EESC) heralding the potential beginning of ozone layer recovery (14% and 27% of the way to 1980 levels for Antarctica and mid-latitudes, respectively).
• To date, no clear indication of the beginning of ozone hole recovery has been observed at the South Pole. At mid-latitudes, ozone depletion has ceased increasing and may be in the first stages of recovery.
• The job is not completed. The ozone hole will last through most of the 21st century. Continued support for long-term measurements of ozone and ozone-depleting substances is necessary. As we look to satellite measurements in the future, we must be vigilant that they are accompanied by accurate surface measurements. We are trying to observe a change of ~1% over a time period of ~10 years!
