Role of Convection over Asian Monsoon/Tibetan Region in Hydration of the Global Stratosphere

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Role of Convection over Asian Monsoon/Tibetan
Region in Hydration of the Global Stratosphere

• Rong Fu1
• Jonathan Wright2, and Yuanlong Hu,1
• Acknowledgment for Science collaboration
  Jonathan H. Jiang3
• 1School of Earth and Atmospheric Sciences,
  Georgia Institute of Technology
• 2 Department of Apply Physics and Mathematics,
  Columbia University
• 3Jet Propulsion Laboratory, California Institute
  of Technology
• Asian Monsoon Year 2008 International Workshop
• Beijing, China, April 23-25, 2007

2

• Acknowledgement
• Prof. Wu, Guoxiong
• NSFC Oversea Young Scientist Project
• NASA Aura Project

3
Asian Monsoon/Tibetan region is a main gateway
for near surface air to enter the lower
stratosphere during boreal summer.
Aura MLS, July 23-29, 2006,

• Chen 1995 Dunkerton 1995 Rosenlof et al. 1997
• Jackson et al. 1998, Randel et al. 2001 Read et
  al. 2004
• Gettelman et al. 2004

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Importance to Global Climate and Stratospheric
Ozone

• Stratosphere water vapor may have increased 2
  ppmv during the 1954 - 2000 period, or 0.7 ppmv
  during 1980-1999. (Oltmans and Huffman 1995,
  Nedoluha et al. 1998, Smith 1999, Rosenlof et al.
  2001).
• If so,
• 1 ppmv increase during 1980-2000 can cause
  0.3K/yr cooling in stratosphere and 0.3 Wm-2
  increase of surface radiative forcing (e.g.,
  DvortsovSolomon 2001 ForsterShine 2002)
• May cause 10 global total ozone decline
  (Stenke et al. 2005).

Increase of cross-tropopause transport in the
Asian monsoon region may contribute to this trend.
Smith 1999
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• How is water vapor transported to the lower
  stratosphere over the Asian monsoon
  region/Tibetan region?
• By monsoon convection or convection over Tibet?
• Dethop et al. 1999 monsoon convection
• Dessler and Sherwood 2004 extratropical
  convection
• Gettelman et al. 2004, Fueglistaler et al. 2005
  both
• Fu et al. 2006 Convection over Tibetan Plateau,
  PNAS

Dessler Sherwood 2004
30N

• Can the lower stratospheric water vapor in the
  Asian monsoon/Tibetan region influence the global
  stratosphere?

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Data Sets

• Aura MLS, water vapor, CO, IWC, (V1.51, Waters et
  al. 2005, IEEE).
• Water vapor (190 GHz) 215 hPa, 147 hPa, 100 hPa,
  68 hPa, 3 km vertical interval, accuracy 10
  at 100 hPa
• CO (240 GHz) accuracy better than 30 at 147 hPa
• IWC (118 GHz) 215 hPa, 178 hPa, 147 hPa, 121
  hPa, 100 hPa, 83 hPa Mainly detect cirrus/anvil,
  insensitive to thin cirrus (Detectable IWC 0.4
  mg/m3 at 147 and 100 hPa, 4 mg/m3 at 215
  hPa,saturate when IWCgt50 mg/m3.)
• Aqua MODIS cloud (MYD08_D3), aerosol (MYD08),
  1º1º, reff, Pcld, fcld, tcld, aerosol optical
  depth (AOD).
• TRMM Precipitation radar (PR, 2A25) along-track
  reflectivity of precipitation sized hydrometeors.
  
• The Goddard Fast Trajectory model (Schoeberl
  and Sparling, 1995) driven by (UKMO) reanalysis
  data updated daily at 12 UTC, 2.5º3.75º lat/lon
  grid.

For the periods of Aug - Sept. 15 2004, July 15 -
Sept. 15 2005
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Where does water vapor enter the lower
stratosphere?
Water vapor at 100 hPa
Probability of Convective Source for high water
vapor at the tropopause
High water vapor (gt 5 ppmv) at 100 hP detected by
MLS during Aug. 2004 and 2005.
Air rich in water vapor also appear to enters the
lower stratosphere primarily over the TP and its
south slope.
Fu et al. 2006, PNAS
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Why Tibet?
Aura MLS clear-sky temperatures
? TP SLP MON
380K 203K 7K 199K 2K 197K
360K 212K 12K 208K 8 K 200K
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• Why is the troposphere-to-stratosphere water
  vapor transport is so strong over the Tibetan
  Plateau?
• Convection penetrates deeper,
• Warmer and less saturated tropopause layer

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• Can the lower stratospheric water vapor in the
  Asian monsoon/Tibetan region influence the global
  stratosphere?

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Water vapor enters the tropical stratosphere
controls water vapor in the global stratosphere
The tropical pipe
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Where is the main source for the seasonal
moistening of the tropical stratosphere?
At 68 mb, MLS H2O gt3.6 ppmv, Oct-Dec, 12S-12N.
40 days ago
80 days ago
120 days ago, July-Sept.
Mostly from the Asian monsoon region!
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How does LS water vapor over Asian
monsoon/Tibetan region enter the tropical
pipe?
Forward trajectory analysis begin with Aura MLS
high water vapor samples (gt 5 ppmv) at 100 hPa
over the Asian monsoon/Tibetan region (gt 2000
samples).
80hPa
70hPa
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Conclusions

• Convective transport over the Tibetan Plateau
  provides a main pathway for water vapor and CO to
  enter the lower stratosphere in the Asian monsoon
  region.
• The summer moistening of the global tropical
  stratosphere is mainly contributed by moist air
  from the Asian Monsoon/Tibetan region.
• Other tracers can be transported by the same
  processes.

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Where is the main source region? Indian
subcontinent or Tibetan Plateau?
Tibetan Plateau 27-35N
Monsoon region 10-25N
743
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What is the role of convection over the Tibetan
Plateau?
Sept. 2005
5 km above sea-level
TRMM PR rainrate (mm/h), JJA, 1998-2000
ISCCP convective clusters

• Convection over Tibet penetrates higher than that
  over Asian monsoon region.

Altitude, km
Fu et al. 2006,GRL
In situ radar, Uyeda et al. 2001