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2007/09/27 Aviation & the Environment: Issues & Methods 2
Aviation and the Atmosphere
• Aviation emissions are deposited directly into the upper troposphere and lower stratosphere with greater warming effect than aviation emissions on the surface.
• Rapid growth in global air travel is anticipated to continue in the near future.
2007/09/27 Aviation & the Environment: Issues & Methods 3
Climatology vs. Meteorology
• Climatology (long time scales)– Provides with a description of the mean state
of the atmosphere and estimates its variability about that state
– Understand the (non-linear) dynamics of climate
• Meteorology (short time scales)– Study of the atmosphere with focus on
weather forecasting
2007/09/27 Aviation & the Environment: Issues & Methods 4
Earth Radiation Balance
• Radiation balance– Radiated Energy from the Sun warms the
Earth.– Energy radiated from Earth to space cools
Earth.– The balance of energy from the Sun and the
energy radiated back to space from Earth result an equilibrium.
– Atmospheric constituents keep average temperature above black body temperature.
2007/09/27 Aviation & the Environment: Issues & Methods 5
How Earth Warms UpThe Energy Difference
2007/09/27 Aviation & the Environment: Issues & Methods 6
Sun & Earth as Blackbodies
Note: Earths’ curve magnified by 500,000 times
2007/09/27 Aviation & the Environment: Issues & Methods 7
Radiation Absorption by Atmospheric Constituents
2007/09/27 Aviation & the Environment: Issues & Methods 8
The Atmospheric Layers
Planetary Boundary Layer
Troposphere
Stratosphere
Tropopause
2007/09/27 Aviation & the Environment: Issues & Methods 9
Fuel Combustion
CO2 + H2O + N2 + O2
NOx + CO + SOx+ Soot +UHC
2007/09/27 Aviation & the Environment: Issues & Methods 10
Fuel Combustion
• The Perfect Combustion
• CnHm + S + N2 + O2 CO2 + H2O + N2 + O2
But in reality
CnHm + S + N2 + O2 CO2 + H2O + N2 + O2
NOx + CO + SOx + Soot + UHC
2007/09/27 Aviation & the Environment: Issues & Methods 11
Possible Impact of Jet Exhaust
• Emissions are accumulated at altitude:– CO2
– H2O
– Soot– Sulfate
• Emissions induce changes in atmospheric composition (chemical reactions)
2007/09/27 Aviation & the Environment: Issues & Methods 12
Accumulation of Emissions
• Increased Radiative Forcing is caused by:– CO2 , H2O, Soot
– Particular matter in exhaust and H2O form jet contrails leading to increased cloudiness
2007/09/27 Aviation & the Environment: Issues & Methods 13
Induced Chemical Changes
• NOx (NO, NO2) affects atmospheric levels of ozone and methane. – It is a precursor to Ozone (O3), but
– In combination with H2O depletes O3
– Oxidizes (CH4) resulting cooling
2007/09/27 Aviation & the Environment: Issues & Methods 14
Emissions Regulations
Current Status
• Only Soot, UHC, CO, and NOx are regulated
• Reducing the level of emissions requires:– International collaboration (Kyoto protocol)– Improved understanding of interrelationships
between various emissions (reduce modeling uncertainties)
2007/09/27 Aviation & the Environment: Issues & Methods 15
Terminology Relating to Atmospheric Particles
Smog A term derived from smoke and fog, applied to extensive contamination by aerosols. Now sometimes used loosely for any contamination of the air.
Smoke Small gas-bome particles resulting from incomplete combustion, consisting predominantly of carbon and other combustible material, and present in sufficient quantity to be observable independently of the presence of other solids. Dp 0.01 .urn.
Soot Agglomerations of particles of carbon impregnated with "tar," formed in the incomplete combustion of carbonaceous material.
Particle An aerosol particle may consist of a single continuous unit of solid or liquid containing many molecules held together by intermolecular forces and primarily larger than molecular dimensions (> 0.001 rn) (can consist of two or more such unit structures held together by inter-particle adhesive forces)
2007/09/27 Aviation & the Environment: Issues & Methods 16
The A-train (Aqua/Aura) Afternoon Constellation
MODIS- AerosolsAIRS Temperature and H2O Profile
Aqua
1:30 PM
Aura
OMI - Aerosol, HCHO, SO2
OMI & HIRLDS – Trop O3,
NO2
TES - Trop O3, CO, CH4,
HNO3
1:38 PMCloudsat
PARASOL
CALIPSO- Aerosol ProfilePARASOL- Aerosol polarization
CALIPSOAURA
2007/09/27 Aviation & the Environment: Issues & Methods 17
Aura Launch July 15, 2004
OMI cut-away diagram
2007/09/27 Aviation & the Environment: Issues & Methods 18
Instruments onboard AURA
• HIRDLS: High Resolution Dynamics Limb Sounder
• MLS: Microwave Limb Sounder
• TES; Tropospheric Emission Spectrometer (Limb & nadir mode)
• OMI: hyper-spectral imaging (nadir mode, VIS & UV))
2007/09/27 Aviation & the Environment: Issues & Methods 19
OMI CCD & Optical Assembly
2007/09/27 Aviation & the Environment: Issues & Methods 20
Observing the Atmosphere from Space
2007/09/27 Aviation & the Environment: Issues & Methods 21
OBSERVATION BY SOLAR OCCULTATION (UV to near-IR)
EARTH
“satellite sunrise” Tangent point; retrieve vertical
profile of concentrations
Recent extensions to lunar and stellar occultation
Examples:SAGE, GOMOS
2007/09/27 Aviation & the Environment: Issues & Methods 22
OBSERVATION BY THERMAL EMISSION (IR, wave)
EARTH SURFACE
Absorbinggas or aerosol
To
T1
LIMB VIEW
NADIRVIEW
Examples: MLS, MOPITT, MIPAS, TES, HRDLS
2007/09/27 Aviation & the Environment: Issues & Methods 23
OBSERVATION BY SOLAR BACKSCATTER (UV to near-IR)
absorption
EARTH SURFACE
Scattering by Earth surface and by atmosphere
Backscatteredintensity IB
Examples: TOMS, GOME, SCIAMACHY, OMI
2007/09/27 Aviation & the Environment: Issues & Methods 24
LIDAR MEASUREMENTS
EARTH SURFACE
backscatter by atmosphere
Laser pulse Examples: LITE, CALYPSO
2007/09/27 Aviation & the Environment: Issues & Methods 25
Hyper-spectral Data Cube
2007/09/27 Aviation & the Environment: Issues & Methods 26
Remote Sensing & Complexity
2007/09/27 Aviation & the Environment: Issues & Methods 27
In-situ Measurements
2007/09/27 Aviation & the Environment: Issues & Methods 28
Putting Together Remote Sensing & In-situ Measurements
Synergy
In-situ Measurements
Remote Sensing
Modeling
2007/09/27 Aviation & the Environment: Issues & Methods 29
Aviation: the visible (environmental) impact
2007/09/27 Aviation & the Environment: Issues & Methods 30
Remote Sensing & the Environment (or prelude to conclusions)
Meterology
WeatherClimatology
Climate
AviationOperations
2007/09/27 Aviation & the Environment: Issues & Methods 31
Conclusions• The aviation’s effect on the global atmosphere is
potentially significant (IPCC 1999)• Improved air traffic operations could reduce aviation
emissions• Enhanced modeling of radiative forcing of jet exhaust
constituents is required to increase the climate forecasting accuracy.
• Modeling Uncertainties– Limited accuracy in quantifying the impact of jet exhaust on the
climate– Limited understanding of how the atmosphere and climate will
respond to human-induced changes in greenhouse gases over the long term
– to improve the scientific understanding and modeling capability to assess aviation climate impacts and reduce key uncertainties associated with these impact
2007/09/27 Aviation & the Environment: Issues & Methods 32
References• P.K. Bhartia: Global Air Quality Study from the A-train, August 2001• D. Jacob: Satellite Observations of Atmospheric Chemistry, August
2001• Aviation and the Global Atmosphere, Intergovernmental Panel on
Climate Change• Evaluation of Air Pollutant Emissions from Subsonic Commercial Jet
Aircraft, EPA, April 1999, EPA420-R-99-013• Reducing the Climate Change Impact of Aviation, Communication
from the Commission to the Council, the European Parliament, The European Economic and Social Committee and the Committee of the Regions, Brussels, September 2005, COM(2005) 459 Final
• Aviation and the Changing Climate, AIAA• Scientific Assessment of Ozone Depletion; 2002, World
Meteorological Organization, Report No. 47• http://mozaic.aero.obs-mip.fr/web/features/information/map.html
