An Evaluation of the UWNMS Treatment of Water Vapor Transport and Cirrus Formation in the UT/LS

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An Evaluation of the UWNMS Treatment of Water
Vapor Transport and Cirrus Formation in the UT/LS

• Monica Harkey, UW-Madison
• Matthew Hitchman, Marcus Buker

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Hypothesis and method

• Changes in tropical cirrus microphysics caused by
  emissions from biomass burning may (partly)
  explain moistening of the lower stratosphere
• UWNMS model runs with control and perturbed ice
  microphysics will show first-order effects on the
  distribution of water vapor in the UT/LS

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The volumes of interest

• in the vertical

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The volumes of interest

• in the horizontal

Jensen et al., 2001
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Where the cirrus areSAGE
Wang et al., 1996
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Where the cirrus areLITE
Winker and Trepte, 1998
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How tropical cirrus form

• wave motions
• from convective influences (anvils, pileus)
• large-scale, slow uplifting

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How clouds affect water vapor in the UT/LS
Rosenfield et al. (1998)
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The knowns

• Water vapor in the lower stratosphere is
  increasing (Rosenlof et al., 2001)
• Cirrus near the tropopause affect water vapor
  transport into the lower stratosphere
• Cirrus occur near tropical tropopause frequently

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Tropical biomass burningAfrica
Image taken by Bob Yokelson during SAFARI
campaign, southern Africa in 2000
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Tropical biomass burningSouth America
MODIS image from 22 July 2003, showing fires
surrounding Xingu National Park (and indigenous
peoples reserve), Brazil
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Where biomass burning products were measured
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How do we know biomass burning was really the
source?
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Where did the material go?
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What are some properties of biomass-burning
plumes?
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What are some properties of biomass-burning
plumes?
Kojima et al., 2004
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How can combustion materials affect ice clouds?

• Kojima et al. (2004) found organics abundant in
  upper troposphere, many sulfate aerosols embedded
  with organics
• Measurement techniques can destroy molecules
  (Cziczo et al., 2004)
• Cziczo et al. also noted organics appear to be
  inefficient IN

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The knowns

• Water vapor in the lower stratosphere seems to be
  increasing
• Cirrus near the tropopause affect water vapor
  transport into the lower stratosphere
• Cirrus occur near tropical tropopause frequently

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the UWNMS

• Arbitrary resolutionused 400 m in the vertical,
  30 km in the horizontal
• Non-hydrostatic model especially needed in region
  of study

For more information on this model, written by
Prof.Greg Tripoli, visit http//mocha.meteor.wisc
.edu/
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the UWNMS

• ECMWF 12-hour, 2.5 x 2.5 degree winds,
  temperature, and moisture up to 200 hPa
• HALOE latitude-binned and pressure-averaged water
  vapor at and above 200 hPa
• Explicit microphysics predict concentration of
  pristine crystals, aggregates
• convective parameterization using Kuo scheme

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the UWNMS and idealized IN

• Control run
• pristine crystals initialized at 1 µm (6.4 x
  10-12 grams for hexagonal plate)
• Perturbed run
• crystals initialized at 0.45 µm (9.1 x 10-13
  grams)

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Pristine crystal concentration at 13.5 km 24
hours into run
Control run
Perturbed run
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Pristine crystal concentration at 13.5 km 30
hours into run
Control run
Perturbed run
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Pristine crystal concentration at 13.5 km 36
hours into run
Control run
Perturbed run
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Pristine crystal concentration at 13.5 km 42
hours into run
Control run
Perturbed run
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Pristine crystal concentration at 13.5 km 48
hours into run
Control run
Perturbed run
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Pristine crystal concentration at 14.5 km24
hours into run
Control run
Perturbed run
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Pristine crystal concentration at 14.5 km30
hours into run
Control run
Perturbed run
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Pristine crystal concentration at 14.5 km36
hours into run
Control run
Perturbed run
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Pristine crystal concentration at 14.5 km42
hours into run
Control run
Perturbed run
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Pristine crystal concentration at 14.5 km48
hours into run
Control run
Perturbed run
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Pristine crystal concentration at 15.5 km24
hours into run
Control run
Perturbed run
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Pristine crystal concentration at 15.5 km30
hours into run
Control run
Perturbed run
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Pristine crystal concentration at 15.5 km36
hours into run
Control run
Perturbed run
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Pristine crystal concentration at 15.5 km42
hours into run
Control run
Perturbed run
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Pristine crystal concentration at 15.5 km48
hours into run
Control run
Perturbed run
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What does this mean, in bulk?
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Water vapor difference at 13.5 km
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Water vapor difference at 14.5 km
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Water vapor difference at 15.5 km
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The difference in water vapor between control and
perturbed runs
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Summary

• As expected,
• crystal mixing ratios higher in perturbed run,
  with smaller (0.45 micron) initial size
• cloud extent between control, perturbed runs
  varies
• ice initialized with a smaller crystal size
  results in an increase of water vapor mixing
  ratio within and above clouds

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Direction for the future

• Fashion idealized gunkbiomass burning derived
  INto be activated at a specific T, q and
  interact with water vapor in the UWNMS
• Conduct sensitivity studies with varying
  concentrationshow do cloud properties, water
  vapor distribution change?