Transcript Document

Intercontinental Transport and Chemical Transformation (ITCT)
An Activity of the International Global Atmospheric Chemistry Project (IGAC)
Today (briefly):
• The inception of ITCT
• Preliminary findings (the scientific basis of ITCT)
• The principle science questions
• The strategy and tools
• Outline of planned research
(More detailed presentations at this meeting)
Inception of ITCT
The International Global Atmospheric Chemistry (IGAC) project was established (1988)
to investigate the impact of chemistry on global climate change. (ozone and aerosols)
Tokyo Workshop (March 16-17, 2000, Frontier Research Systems for Global Change).
Steering committee formed; white paper accepted by IGAC; ITCT steering committee
met (June 6 -7) and outlined a science plan.
ITCT was formulated with the recognition that climate change had regional as well
as global dimensions and ozone and aerosols had air quality, as well as, climate
change implications.
Focus of ITCT: The Northern Hemisphere
Focus on shorter-lived pollutants; ozone, aerosols.
Much of the anthropogenic sources are in the
Northern Hemisphere.
For short-lived species, the ITCZ represents a line of
demarcation that separates the world into two unique
chemical zones; the Northern, where most of the land
is, and the Southern, which is dominated by water.
Since compounds are short-lived, most of the impact
is in the Northern Hemisphere.
The public concern with the chemical aspects of these species is strongly involved with airquality (human and ecosystem impacts as opposed to climate). ITCT will try to address both
regional climate and air-quality concerns.
White papers available.
PRELIMINARY FINDINGS
The Scientific Basis of ITCT from a Transatlantic Perspective
(c.f., Parrish and Jacob this afternoon)
Large Amounts of Ozone Are
Transported to the Remote
Troposphere
There is a strong seasonal
variation in the anthropogenic
influence on the tropospheric
O3 budget.
0 .5
C ap e Ra c e
S ea l Is .
S a b l e Is
0 .4
M ay
J un e
J u ly
0 .3
Sept
J ul
0 .2
0 .1
J un e
S ep t A u g
Jul
Aug
a ll
Au g
Apr
O ct
8/28/ 93;
0 .0
F eb
Mar
De c
Nov
- 0 .1
1400GMT ; 0.471 km
Jan
- 0 .2
0 .0
0 .2
0 .4
r2
(Parrish et al.)
0 .6
0 .8
1 .0
20
30
40
50
60
70
80
90 10 0 11 0 1 20 130 1 72
Ozone mixing ratio (ppbv)
Identification of controlling
meteorology
Layers provide an effective
mechanism for the transport of
continental pollution to mid and
upper troposphere of the North
Atlantic (Angevine et al.).
F R EE
TR O PO SPH E R E
D ry, W arm er
In vers ion
W arm ,
T u rbu len t
W arm ,
N on -tu rb u len t
M A R IN E B O U N D A R Y L A Y E R
C ool, n on -tu rb u len tal
Transport enhanced by fronts.
Layers can be dominated by anthropogenic pollution or by
stratospheric O3 (c.f., Stohl et al.).
(Topics described in posters: Cooper, McCaffery and McKeen.)
NOx controls photochemical O3
formation over the North Atlantic
CO
NOy
CO (ppbv)
Bkgd +Stratosphere
Bkgd + Anthropogenic
6
5
20 0
100%
2
10
Emissions from forest fires influence
air-quality on a hemispheric scale.
50%
18 0
16 0
= 127 ppbv
B
B
= 0.3 ppbv
20%
14 0
N O y (p p b v )
4
3
10%
12 0
10 0
2
5%
80
1
92
90
2%
94
Year
6
5
4
3
2
0.1
5
(Parrish)
6
7
8
Estimate : About 5%
of NO x transported
9
2
3
4
98
√
CO (Wotawa and Trainer)
√
O3, NOx (McKeen et al.)
5
100
CO (ppbv)
96
? Aerosols
00
FUTURE PLANS
(Science Questions, Approach, Plans ITCT from a Transatlantic Perspective)
THE PRINCIPAL SCIENCE QUESTIONS
What are the export fluxes of oxidants,
aerosols, and their precursors from
the Northern Hemisphere continents
to the global atmosphere?
What is the ultimate fate of these
substances exported to the global
atmosphere?
What are the impacts of intercontinental transport in the Northern Hemisphere on
surface air quality?
What are the impacts of changing emissions on regional and global atmospheric
chemistry, composition, and climate?
What are the impacts of climate variability on regional and global atmospheric
chemistry and composition?
THE STRATEGY AND TOOLS
In order to quantify intercontinental transport and chemical transformation
observations and models must be integrated.
SATELLITE OBSERVATIONS
Global and continuous but
few species, low resolution
Question - HOW
SURFACE OBSERVATIONS
high resolution but spatially limited
3-D CHEMICAL
TRACER MODELS
AIRCRAFT OBSERVATIONS
High resolution, targeted flights
provide critical snapshots
for model testing
Agreement with
reasonable uncertainty
Source/sink
inventories
Assimilated
meteorological
data
Chemical
and aerosol
processes
INTERCONTINENTAL TRANSPORT:
CONCENTRATIONS AND FLUXES
OUTLINE OF PLANNED RESEARCH
Transpacific
1. 2001 - 2002: APARE (ACE and TRACE) interpretation.
2. 2002 - :North American inflow experiment, scooping study and
interpretation. Planning further inflow out flow experiments.
Transatlantic
1. 1997 - 2001: NARE interpretation.
2. 2001 - 2003: Development of Azores sampling site to add to
measurements at other locations.
3. 2002 - : Planning future inflow/outflow experiments.
Trans-Eurasian
•
Establishment of Chinese and Russian sites and/or platforms.
•
Planning European outflow and Asian inflow experiments.
Exchange with Polar and Tropical Regions
•
Mid-latitude industrial emissions.
•
Boreal, tropical biomass burning.