Christopher J Cox University of Idaho, Geography

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Christopher J CoxUniversity of Idaho, Geography
Measuring Atmospheric Changes in the Arctic
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Acknowledgments

• Von Walden (UI), Penny Rowe (UI), Matt Shupe
  (UC, Boulder
• Mike Town (UW), Ed Eloranta (U Wisconsin)
• Funding by National Science Foundation (NSF)
• NOAA SEARCH, CANDAC, ARM, SSEC, IGRA, NSIDC

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Outline

• What is climate change?
• The Arctic Climate System
• Instrumentation
• Preliminary research
• Conclusion

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What is Climate Change?Scientific Consensus

• Warming of the climate system is unequivocal, as
  is now evident from observations of increases in
  global average air and ocean temperatures,
  widespread melting of snow and ice and rising
  global average sea level (WGI 3.9, SPM)
• Intergovernmental Panel on Climate Change (IPCC)
• Climate change no longer a scientific debate, but
  a societal issue

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What is Climate Change?The Greenhouse Effect
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What is Climate Change?The Greenhouse Effect
Global atmospheric concentrations of carbon
dioxide, methane, and nitrous oxide (all
greenhouse gases) have increased markedly as a
result of human activities since 1750.
IPCC WG1.2 Figure 1
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What is Climate Change?The Greenhouse Effect
A1Fl Aggressive Scenario (850 ppm)
Potential Human Contribution
A1B Medium Scenario (700 ppm)
B1 Green Scenario (550 ppm)

Natural Variability
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What is Climate Change?The Greenhouse Effect
So what about Arctic? Primarily as a result of a
strong ice-albedo postive feedback, the Polar
Regions are very sensitive to a warming
climate. But, they are also poorly quantified!
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Previous Research
Arctic atmosphere Surface Heat Budget of the
Arctic (SHEBA) Intrieri et al (2002) An annual
cycle of Arctic surface cloud forcing at
SHEBA Shupe et al (2005) Arctic mixed-phase cloud
properties from surface-based sensors at
SHEBA Other Key et al (2004) Cloud distributions
over the coastal Arctic Ocean surface-based and
satellite observations Shupe Intrieri (2003)
Cloud Radiative Forcing of the Arctic Surface
The Influence of Cloud Properties, Surface
Albedo, and Solar Zenith Angle Tjernstrom et al
(2004) The Summertime Arctic Atmosphere
meteorological measurements during the Arctic
Ocean Experiment 2001 Verlinde et al (2004)
Mixed-Phase Arctic Cloud Experiment
(M-PACE) Recent Sea Ice Melt Drobot et al (2008)
Evolution of the 2007-2008 Arctic sea ice cover
and prospects for a new record in 2008 Kay et
al (2008) The contribution of cloud and
radiation anomalies to the 2007 Arctic sea ice
extent minimum Perovich et al (2008) Sunlight,
water,and ice Extreme Arctic sea ice melt during
the summer of 2007 Schweiger et al (2008) Did
unusually sunny skies helpdrive the record sea
ice minimum of 2007? Zhang et al (2008) What
drove the dramatic retreat of arctic sea ice
during summer 2007?
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The Arctic Climate System
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Signs of Arctic Climate Change
National Snow and Ice Data Center (NSIDC)
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Instruments now in the Arctic

• Polar Atmospheric Emitted Radiance Interferometer
  
• Arctic High Spectral Resolution Lidar (AHSRL)
• Ed Eloranta (SSEC. U. Wisconsin-Madison)
• Millimeter Cloud Radar (MMCR)
• NOAA ERL, Boulder, CO
• Microwave Radiometer (MWR) - total column water
  vapor
• NOAA ERL, Boulder, CO
• Radiosondes from the Eureka Weather Office
• http//lidar.ssec.wisc.edu/

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Instrument Specs AHSRL
Arctic High Spectral Resolution Lidar (AHSRL)
LIDAR Light Detection and Ranging
40 ns pulse width Wavelength 523
nm
http//lidar.ssec.wisc.edu/
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Instrument Specs MMCR
Millimeter Cloud Radar Zenith pointing
radar Operates at 35 Ghz Used to determine cloud
boundaries

http//arm.gov/
http//lidar.ssec.wisc.edu/
www.arm.gov
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Instrument Specs MWR
Microwave Radiometer Measure microwave emission
from water (liquid/vapor) Reports column
integrated amounts

http//arm.gov/
http//lidar.ssec.wisc.edu/
www.arm.gov
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Instrument Specs PAERI

• Polar Atmos. Emitted Radiance Interferometer
• Spectral infrared radiance from 3 to 20 mm (1
  cm-1)
• Two detectors MCT - LW and InSb - SW
• Very accurate 1 (3?) of ambient radiance

http//lidar.ssec.wisc.edu/
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PAERI
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PAERI
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PAERI

• What can we use PAERI output for?
• Cloud fraction
• Trace gas measurements
• Scale radiosondes
• Validate satellites
• Longwave cloud radiative forcing
• more

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Instrument Sites
Eureka, Nunavut, Canada Study of Environmental
Arctic Change (SEARCH) Arctic Observing Network
(AON) at Canadian Network for the Detection of
Arctic Change (CANDAC) site 79º59N,
85º57W Barrow, Alaska Atmospheric Radiation
Measurement (ARM) North Slope Alaska (NSA)
site 71º18N, 156º44W
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Longwave Downwelling Radiation and Arctic Sea Ice
Melt

• Preliminary experimental evidence for the
  importance of downwelling longwave radiation to
  the recent decrease in sea ice concentration over
  the Arctic Ocean.
• Was shortwave downwelling radiation (SDW) the
  cause?
• Kay et al (2008) The contribution of cloud and
  radiation anomalies to the 2007 Arctic sea ice
  extent minimum
• Perovich et al (2008) Sunlight, water,and ice
  Extreme Arctic sea ice melt during the summer of
  2007
• Was it longwave downwelling radiation (LDW)?
• Schweiger et al (2008) Did unusually sunny skies
  helpdrive the record sea ice minimum of 2007?

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Schweiger et al (2008)
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Surface Temperature
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Tropospheric Temperature
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Fractional Cloud Cover
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Precipitable Water Vapor
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Calculating DLW Flux and LWCRF
AERI measurements made at zenith Out of band
radiance was simulated as a black body using
brightness T from 650-660 cm-1 Assume isotropic
radiance (fluxes within 5) Focusing on Eureka
data only LW CRF All Clear (Ramanathan et al,
1989)
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Differences in DLW and CRF

• LWCRF depends on many variables
• FCC
• Optical thickness of clouds
• AND Temperature of the near-surface air (in
  winter)

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Cloud Forcing
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Inter-annual Variations at Eureka
Eureka Summer Average (JJA) Eureka Summer Average (JJA) Eureka Summer Average (JJA) Eureka Summer Average (JJA)
Year LW-CRF (W m-2) All Sky Flux (Wm-2) FCC ()
2006 42 275 78
2007 18 263 54
2008 27 268 63
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Conclusions

• The phenomenon of accelerated climate change is
  a scientific consensus
• The Arctic is environment is very sensitive to a
  warming climate and is poorly quantified
• Recent sea ice retreat may be signs of a
  changing climate system
• Determining the potential causes of recent sea
  ice decrease in the Arctic is complicated
• Experimental evidence may show that the all-sky
  flux has influenced sea ice retreat through an
  increase in the near surface temperature and/or
  increases in humidity

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Sources

• Drobot, S Stroeve, J Maslanik, J Emery, W
  Fowler, C, and Kay, J. 2008. Evolution of the
  2007-2008 Arctic sea ice cover and prospects for
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• Intrieri, JM Shupe, MD Uttal, T McCarty, BJ.
  2002. An annual cycle of cloud characteristics
  observed by radar and lidar at SHEBA Jounal
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  107C10(8030).
• IPCC, 2007, Climate change (2007) Synthesis
  Report, Summary for Policy Makers, 22p.
• Kay, J LEcuyer, T Gettelman, A Stephens, G
  and ODell, C. 2008. The contribution of cloud
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• Perovich, DK Richter-Menge, JA Jones, KF
  Light, B. 2008. Sunlight, water, and ice
  Extreme Arctic sea ice melt during the summer of
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• Ramanathan, V Cess, RD Harrison, EF Minnis,
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• Shupe. MD and Intrieri, JM. 2003. Cloud
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  and Solar Zenith Angle. Journal of Climate. Vol.
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• Schweiger, AJ Zhang, J and Steele, M. 2008.
  Did unusually sunny skies help drive the record
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• Tjernström, M Leck, C Ola, P Persson, G
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• Town, MS Walden, VP and Warren, S. 2005.
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• Zhang, J Lindsay, R Steele, M and Scheiger,
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