TROPOSPHERIC OZONE AND AEROSOLS MAKE LARGE AND INHOMOGENEOUS CONTRIBUTIONS TO RADIATIVE FORCING IPCC 2001 contribution from Harvard/GISS/Caltech/UCI unified aerosol-chemistry-climate model (CACTUS)
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
REGIONAL/GLOBAL INTERACTIONS IN ATMOSPHERIC CHEMISTRY
(collaborations with NASA/GSFC, Duke, U. Washington) – Satellite retrievals: formaldehyde, NO2, CO, ozone– Chemical forecasts: TRACE-P, NOAA 2002
APPLICATION OF GEOS-CHEM TO THE ORIGIN OF BACKGROUND OZONE IN U.S. IN SUMMER 1995
[Fiore et al., 2001]
• NASA/GEOS assimilated meteorological data for 1995 • 2ox2.5o horizontal resolution, 26 vertical layers• 120 chemical species (O3-NOx-hydrocarbon chemistry);
aerosol effects on chemistry, radiation • SAMI July 1995 inventory for eastern U.S.
Evaluation with AIRS, SOS, NARSTO-NE observations
SUMMER 1995 AFTERNOON OZONEIN SURFACE AIR OVER THE U.S.
AIRS observations
GEOS-CHEM(r2 = 0.4, bias=3 ppbv)
FREQUENCY DISTRIBUTION OF SURFACE p.m. O3
IN WESTERN MASSACHUSETTS IN SUMMER 1995
Observations(squares, triangles)
Model(crosses) Air quality
standard
MEAN AFTERNOON OZONE BACKGROUNDIN MODEL, SUMMER 1995
Background is tagged as ozone produced outside the N. American boundary layer (surface-700 hPa)
OZONE BACKGROUND IS DEPLETED DURING REGIONAL POLLUTION EPISODES
(due to stagnation, short O3 lifetime)
Background(clean conditions)
O3 vs. (NOy-NOx) At Harvard Forest, Massachusetts
Background(pollution episodes)
FREQUENCY DISTRIBUTION OF AFTERNOON BACKGROUND OZONE CONCENTRATIONS
IN U.S. SURFACE AIR IN SUMMER 1995 (model)summer ensemble vs. pollution episodes
Convection upwindoccasionally results inhigh background during pollution episodes
Convection upwind can result in high background contributions to ozone pollution episodes
Time, days0 1 2 3
Subsidence inversion
Boundarylayer
Free troposphere
Ozonedowndraft
fast ozoneproduction
> 50 ppbv day-1
Convectivecloud
Ozone pollutionepisode
ASIAN/EUROPEAN POLLUTION ENHANCEMENTOF BACKGROUND OZONE IN U.S.
Mean model values, summer 1995 (4ox5o resolution)
“Natural” background(no anthropogenicemissions of NOx
or NMHCs anywhere,but present-day CH4)
Asian/Europeananthropogenicenhancement abovenatural background (no anthropogenicemissions in North America)
RANGE OF ASIAN/EUROPEAN POLLUTION OZONE ENHANCEMENTS OVER THE UNITED STATES
ensemble of model results, summer 1995
Max enhancements(up to 14 ppbv)under moderatelypolluted conditions(50-70 ppbv O3)associated with recent convection
MAJOR CONCERNIF OZONE STANDARDWERE TO DECREASETO 40 or 60 PPBV
CONCLUSIONS
• Surface ozone in U.S. in summer includes a 20-40 ppbv background originating from outside North America
• Present-day Asian emissions enhance this background by 3-7 ppbv (up to 14 ppbv)
• Asian influence on surface ozone in U.S. is highest under moderately polluted conditions (50-70 ppbv), less during acute pollution episodes (> 80 ppbv) or clean conditions
(< 40 ppbv)
• Importance of background will increase in the future due to rise in Asian emissions, lower metrics for ozone standard.
FUTURE WORK• EPA/Harvard modeling collaboration
– Examine ozone perturbations from intercontinental transport for future scenarios and sensitivity studies
– Examine intercontinental transport of aerosols, ozone-aerosols coupling– Couple Models-3 and GEOS-CHEM to extend the nested-model capability of
Models-3 to the global scale.
• Analysis of aircraft data directed at intercontinental transport: – TRACE-P, spring 2001 (Asian outflow)– NOAA/ITCT, spring 2002 (North American inflow)– INTEX/NA, summer 2004 (North American outflow/inflow)
• Assimilation of satellite observations into global models– Use global mapping capabilities from satellites to test model simulations of
intercontinental transport for CO, ozone, aerosols