A U.S. NOAA airborne project in the Arctic for the International Polar Year IPY

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• A U.S. NOAA airborne project in the Arctic for
  the International Polar Year (IPY)
• Quick overview of science issues
• Specific questions we can address
• Planned measurements
• Interactions with other field programs

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• What are human-caused processes (other than
  long-lived GHG-induced climate change) that may
  increase Arctic warming and/or sea ice melt?
• Lower tropospheric warming due to absorption of
  solar radiation by soot particles
• Decrease in snow albedo by deposited soot
• Increase in IR emissivity of clouds by aerosol
  indirect effect
• Tropospheric O3 forcing (local IR and global)

These are all short-lived species and therefore
respond RAPIDLY to changes in emissions IPY is
an opportunity to improve understanding of all of
these processes
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• Lower tropospheric warming due to absorption of
  solar radiation by soot particles
• Decrease in snow albedo by deposited soot
• Increase in IR emissivity of clouds by aerosol
  indirect effect

These 3 processes are all driven by aerosol
particle properties and concentrations and are
important in winter and spring. Arctic
springtime aerosol properties are dominated by
anthropogenic emissions and transport (Arctic
haze).
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Two long-term North American surface sites
Barrow, Alaska and Alert, Canada
Barrow
Alert
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• Monthly mean aerosol mass shows consistent annual
  cycle
• Peak in January-April--variation with altitude?
• Mostly sulfate
• Nitrate 10 of sulfate
• Little info on organic mass
• Arctic-wide

Quinn et al., Tellus B
Sulfate Nitrate
Sulfate Nitrate
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Sources for surface haze generally lie within the
Arctic front Layers aloft may have sources
further south (if they can survive cross-front
processes)
Arctic Monitoring and Assessment Programme, 2006
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Anthropogenic sources of soot (industrial and
biofuel) Sources in northern Europe and NE China
are consistently within or near the mean position
of the Arctic front. Stohl et al., 2006
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What happens to pollutants within the Arctic?
Arctic age of air How long air parcels have
spent poleward of 70 oN (lowest 100m shown
here) North American side of Arctic is more aged
than Eurasian side (more transport on Eurasian
side) Aloft, flow is more meridional (Greenland)
Barrow
Alert
Stohl et al., 2006
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The Arctic is Stable April Temperature Profiles
at Barrow

• Strong inversion
• Surface often decoupled from air aloft
• Clouds can (and do) have liquid water even in
  winter and spring
• Clouds may be warmer than the surface
• This inversion occurs over ice surface, not over
  open ocean

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Result is very stable atmosphere, stratiform
layers, and decoupling of surface aerosol from
transport aloft. ? A reason for an aircraft
mission. Surface and layers aloft often are
linked only via radiation and mass transfer
(precipitation)
3 km
40 km
Aerosol Backscatter
0 km
Downward-looking airborne aerosol lidar image of
haze layers near Baffin Island, Canada in 1986.
(Radke et al., 1989)
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(No Transcript)
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August 1985 Dense summertime smoke layers aloft
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April 1983 Dense pollution layers aloft
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April 1986 Layers aloft, more diffuse near
surface
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• Processes we can study
• Lower tropospheric warming due to absorption of
  solar radiation by soot particles
• (The Arctic, with its stable atmosphere and
  highly reflective surface, offers a unique
  natural laboratory for studying the effects of
  soot on the atmosphere.)

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• Direct radiative forcing of the haze layers is
  poorly quantified (literature varies!), but
  generally
• Lower atmospheric heating rates of 0.1-0.5 K/day
  are calculated in springtime
• Single scatter albedo scattering/(scattering
  absorption) is critical in determining
  atmospheric heating vs. surface cooling
• IR emissions from the layers appear to be
  important
• Hygroscopicity, which changes single scatter
  albedo and IR emissions, is virtually unmeasured
  in Arctic
• Sun angle and surface albedo play important roles

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• Processes we can study
• Lower tropospheric warming due to absorption of
  solar radiation by soot particles
• Decrease in snow albedo by deposited soot
• (We cant study this directly from an aircraft,
  but we can measure soot concentrations in the air
  and in ice nuclei. We can also look for reduced
  soot concentrations in air recently influenced by
  snowfall. These measurements help constrain soot
  deposition.)

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• Processes we can study
• Lower tropospheric warming due to absorption of
  solar radiation by soot particles
• Decrease in snow albedo by deposited soot
• Increase in IR emissivity of clouds by aerosol
  indirect effect

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• Processes we can study
• Lower tropospheric warming by absorption of solar
  radiation by soot particles
• Decrease in snow albedo by deposited soot
• Increase in IR emissivity of clouds by aerosol
  indirect effect
• Tropospheric O3 forcing (local IR and global)
• (we cant really study this directly, but we
  can measure O3 precursors, production, transport,
  and loss, which helps constrain models)

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• Climate-relevant science NOAA will address for
  IPY
• Direct effect Particle characteristics, soot
  abundance, source type, transport
• Indirect effect Cloud properties, particle
  effects on clouds
• Indirect effect Soot nucleation, incorporation
  in clouds
• Ozone abundance, sources, transport

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• Funded by NOAA 4-week P-3 project,
• Fairbanks, AK in April 2008
• 1 week of ferry and instrument testing
• 3 weeks of intensive field observations from
  Fairbanks begining April 1
• Flights from Fairbanks toward Barrow to link with
  NOAA-GMD/DOE-ARM site providing intensive
  surface observations
• Coordinate with NASA and DOE-ARM airborne
  observations
• Coordinate with UW/UH snowfall and snow sampling
  for carbon soot
• Coordinate with UAF observations

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Why Fairbanks?

• 3 big airports
• Accomodations
• Infrastructure
• Shipping
• Not remote, but close to Arctic

Fairbanks
Approximate 2 and 4 hour P3 radii AMSR sea ice
on April 15, 2006
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Expected ARCPAC Payload
Aerosol physical, optical chemical properties
- Single particle soot photometer customized at
NOAA - Cavity-ringdown aerosol extinction
with RH control--f(rh) - Particle soot
absorption photometer - Bulk, size resolved,
and single particle composition - Size
distributions - Solar spectral flux radiometer
(Peter Pilewskie, Univ. Colorado),
actinic flux radiometer Instruments for
studying cloud properties - DMT, Inc. cloud and
aerosol spectrometer, cloud combination probe,
precipitation imaging probe. - Liquid water
content and total water content sensors -
Cloud condensation nucleus counter (DMT Inc.,
Thanos Nenes, Georgia Tech.) - IN chamber with
CVI for examing black carbon nucleation (Sierau
et al., ETH Zurich) - IR pyrgeometers (Peter
Pilewskie, Univ. Colorado)
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Expected ARCPAC Payload
Gas phase measurements - O3, CO, CO2, NOy, NO2,
NO, HNO3, PANs, SO2 - ClNO2, BrCL2, BrCl, BrO
(CIMS under development) - VOC trace gases from
cannisters CFCs, HFCs, alkanes, others?
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Combining Models and Measurements
Measurement In situ particle composition/size
distribution, cloud condensation- and ice- nuclei
spectra, cloud particle concentration, phase,
size In situ cloud dimension and
up/downdraft velocity, cloud particle
concentration, phase, size, solar and IR
transmission/emission Surface-based remote
sensing measurements of cloud dynamics, phase,
precipitation, radiative characteristics,
particle size, phase In-situ particle
composition/size distribution near and below
cloud. Surface measurements of soot concentration
in newly fallen snow Gas phase chlorine
compounds, sea salt aerosol chemistry, actinic
fluxes
Simulation Parcel model of cloud formation, ice
nucleation and growth Large eddy simulation
(LES) with coupled cloud dynamics, microphysics,
radiation in 3D Eulerian framework LES with
coupled cloud dynamics, microphysics, radiation
in 3D Eulerian framework LES with in- and
below-cloud aerosol scavenging Parcel model
with heterogeneous chemistry
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• Linkages with other programs
• NASA aircraft with ARCTAS program and Environment
  Canada aircraft at Fairbanks
• DOE ARM (cloud, radiation) and NOAA GMD (aerosol
  and gas-phase chemistry) sites at Barrow
• NOAA-sponsored vessel in Atlantic looking (we
  hope) at fresher Arctic haze properties
• Snowfall and snow soot samples across the North
  American Arctic
• Other international airborne and surface
  deployments associated with POLARCAT