1 / 11

Tropical Mid-Tropospheric CO 2 Variability driven by the Madden-Julian Oscillation

Tropical Mid-Tropospheric CO 2 Variability driven by the Madden-Julian Oscillation. King-Fai Li 1 , Baijun Tian 2 , Duane E. Waliser 2 , Yuk L. Yung 1 1 California Institute of Technology, Pasadena 2 Jet Propulsion Laboratory, Pasadena Special Thanks to Dr. Peter Bechtold (ECMWF).

corine
Download Presentation

Tropical Mid-Tropospheric CO 2 Variability driven by the Madden-Julian Oscillation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Tropical Mid-Tropospheric CO2 Variability driven by the Madden-Julian Oscillation King-Fai Li1, Baijun Tian2, Duane E. Waliser2, Yuk L. Yung1 1 California Institute of Technology, Pasadena 2 Jet Propulsion Laboratory, Pasadena Special Thanks to Dr. Peter Bechtold (ECMWF) Li et al. (2010), PNAS 107, 19171

  2. Motivation • AIRS CO2 (~5 km) reveals influences from circulations • Surface sources appearing in mid-troposphere • Convection and stratosphere-troposphere exchange • Jet-streams, synoptic weather systems • How does tropical dynamics matter? [A54D-02: ENSO] Chahine et al. [2008]

  3. Madden-Julian oscillation • Dominant form of intraseasonal variability in the tropics • Strongest during boreal winters • Slow (~5 m/s) eastward-propagating oscillations in tropical deep convection and large-scale circulation • Life cycle ~ 60 days Madden & Julian [1971; 1972], Lau and Waliser [2005], Zhang [2005]

  4. AIRS CO2 • Retrieved from 690 – 725 cm-1 • 2.5°×2° gridded Level 3 • Cloud-cleared • Nov 2002 – Feb 2010 • Sensitivity peak at 5 – 10 km • Accurate to 1 – 2 ppmv Chahine et al. [2008]

  5. Methodology • Intraseasonal anomalies of daily data were obtained by • a. Including boreal winter data only • b. Removing the climatological seasonal cycle • c. Bandpass filtering (30–90 days) • MJO phase determined by a pair of Real-time Multivariate MJO indices (RMM1 & RMM2, 1974–present) [Wheeler & Hendon, 2004] http://www.cawcr.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/ • Composite MJO cycle calculated by averaging bandpassed daily anomalies for each phase

  6. RMM Index • Defined as two leading extended EOFs of 36-year OLR data • RMM1− enhanced convection over the Maritime Continent • RMM2− enhanced convection over the Pacific Ocean • (RMM1,RMM2) characterizes the eastward propagation • Use only strong MJO events (RMM12 + RMM22 ≥ 1) × × × × × × × × × × × × × × × ×

  7. Modulated CO2 • Enhanced CO2 over convective regions Li et al., PNAS, 2010

  8. Small Bias due to H2O Absorption • MJO of H2O at 600 hPa ≈ 1.4 g/kg [Tian et al., 2006] • Potential Bias in CO2 ≈ 1.4  0.13 < 0.2 ppmv Observations between 10°S – 10°N Li et al., PNAS, 2010

  9. Vertical Gradient • Verification of vertical gradient using in situ measurements Li et al., PNAS, 2010

  10. Summary • First observation of intraseasonal variability in CO2 • Lower-tropospheric vertical motions drive the MJO of mid-tropospheric CO2 • Vertical gradients in CO2 • Statistically robust • > 20 MJO events and 9 millions of AIRS retrievals being used • Negligible effects due to H2O • Average MJO amplitude ~1.5 ppmv = 0.5% • Critical for determining surface CO2 sources and sinks [Rayner & O’Brien, 2001] • Not seen in ECMWF’s GMES-MACC assimilated CO2 [provided by Dr. Bechtold] • Relationship between tropical dynamics and CO2 not well understood

  11. Thank you! Li et al. AGU Fall 2010 A54D-01

More Related