Large Particles in the Tropical Lower Stratosphere, In Situ Size Distributions

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Large Particles in the Tropical Lower
Stratosphere, In Situ Size Distributions
Terry Deshler and Jennifer Mercer Department of
Atmospheric Science, University of Wyoming

• With acknowledgments to
• Jean-Pierre Pommereau, Anne Garnier, Service
  dAeronomie, and the balloon teams of the Centre
  National dEtudes Spatiales (CNES), France for
  assistance with the Brazilian and Nigerien
  measurements
• Anthony Noonan, Brad Atkinson, and Peter May,
  Bureau of Meteorology, Darwin, Australia, for
  assistance with the Australian measurements
• Gerard Capes, Hugh Coe, University of Manchester,
  UK, for collaborating with us for the AMMA
  campaign in Niger, 2006
• US National Science Foundation for support of
  these measurements.

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Clouds
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UTLS Aerosol Layer
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Origin of particles between 1 and 4 µm at
altitudes of 3 to 6 km (200 K) above the
tropopause?
Ice, Nitric acid trihydrate?
No Temperatures too warm Size distributions do
not conform to either cirrus or other
stratospheric (NAT) clouds
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Volcanoes
Mount Cleveland on 23 May 2006 Jeffrey N.
Williams, Flight Engineer and NASA Science
Officer, International Space Station Expedition
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Bulletin of the Global Volcanism Network (April
2006)
Ash to 3 km
9 May 2006 ash to 15 km
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Bulletin of the Global Volcanism Network (July
2006)
2-3 km
7-8 km
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Bulletin of the Global Volcanism Network (June
2006)
Ash cloud to 5 km
Eruptions to 3 km
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15 Jul 2006 Plume rose to 15 km altitude.
Bulletin of the Global Volcanism Network (July
2006)
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East of Niamey
No Calypso data available for 28 July
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East of Niamey
West of Niamey
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MODIS Optical Depth, 31 July 2006
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MODIS Optical Depth, 31 July 2006
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Forest fires
MODIS Aqua image Central Siberian Plateau
forest fires burning July 24, 2006
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Deep Convection
MODIS Terra image July 25, 2006
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28 July 2006, 0930
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28 July 2006, 1030
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28 July 2006, 1130
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28 July 2006, 1230
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28 July 2006, 1430
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28 July 2006, 1630
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28 July 2006, 1830
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28 July 2006, 1930
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28 July 2006, 2230
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29 July 2006, 1930
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30 July 2006, 1800
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30 July 2006, 2100
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31 July 2006, 0000
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31 July 2006, 0300
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31 July 2006, 0600
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31 July 2006, 0800
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31 July 2006, 1000
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31 July 2006, 1300
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31 July 2006, 0000
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31 July 2006 1110
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Origin of particles between 1 and 4 µm at
altitudes of 3 to 6 km (200 K) above the
tropopause?

• Ice, nitric acid trihydrate? - No
• Temperatures too warm
• Size distributions do not conform to measurements
  within cirrus or polar stratospheric clouds.
• Volcanic? - No
• No obvious major recent eruptions for the
  measurements.
• For the Nigerien measurements the Ecuadorian
  eruption is too low and observations exceed
  expectations from such an eruption.

• Based on observed size distributions, and
  comparisons with tropospheric particle size
  distributions, we believe
• The measurements capture aerosol remnants of
  overshooting thunderstorms
• The penetration of lower tropospheric / surface
  aerosol is 3 to 6 km into the tropical
  stratosphere!
• The transport is common. Measurements are
  sparse, yet frequency of observations is high.
• The phenomenon is highly local. Large differences
  in ascent descent profiles separated a few
  kilometers horizontally

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