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

1. 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

4. Importance to Global Climate and Stratospheric Ozone: Increase of cross-tropopause transport in the Asian monsoon region may contribute to this trend. • 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., Dvortsov&Solomon 2001; Forster&Shine 2002) • May cause ~ 10% global total ozone decline (Stenke et al. 2005). Smith 1999

5. Dessler & Sherwood 2004 • 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 30N • Can the lower stratospheric water vapor in the Asian monsoon/Tibetan region influence the global stratosphere?

6. 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 IWC>50 mg/m3.) • Aqua MODIS cloud (MYD08_D3), aerosol (MYD08), 1º´1º, 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, 2.5º´3.75º lat/lon grid. For the periods of Aug - Sept. 15 2004, July 15 - Sept. 15 2005

7. TRMM PR>18dBz above 10 km MLS high H2O Goddard fast trajectory model forced by UKMO winds for upto 5 days. Water vapor at 100 hPa: Probability of Convective Source for high water vapor at the tropopause: Where does water vapor enter the lower stratosphere? High water vapor (> 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

8. Aural MLS, Aug-Sept 04,05 TP MON monsoon TP TRMM PR Aura MLS TP monsoon Why Tibet? Aura MLS clear-sky temperatures:

9. 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

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

11. ? Mote et al. 1995, 1996: The “tape recorder” Holton et al. 1995 Source: Pan et al. 2006, UCAR TIIMES Water vapor enters the tropical stratosphere controls water vapor in the global stratosphere: The “tropical pipe”

12. Where is the main source for the seasonal moistening of the tropical stratosphere? At 68 mb, MLS H2O >3.6 ppmv, Oct-Dec, 12˚S-12˚N. 40 days ago 80 days ago 120 days ago, July-Sept. Mostly from the Asian monsoon region!

13. MLS “tape record” 5S-5N ~70hPa 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 (> 5 ppmv) at 100 hPa over the Asian monsoon/Tibetan region (> 2000 samples). ~80hPa ~70hPa

14. 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.

15. 739 Where is the main source region? Indian subcontinent or Tibetan Plateau? Tibetan Plateau: 27˚-35˚N Monsoon region: 10˚-25˚N 743

16. What is the role of convection over the Tibetan Plateau? • Convection over Tibet penetrates higher than that over Asian monsoon region. Sept. 2005 5 km above sea-level TRMM PR rainrate (mm/h), JJA, 1998-2000 ISCCP convective clusters Altitude, km Fu et al. 2006,GRL In situ radar, Uyeda et al. 2001