1. Upper-Air Inter-Comparison Experiment Update Presented By Philippe Peylin on behalf of Christopher Pickett – Heaps & Peter Rayner

2. Purpose of the experiment…  An inter-comparison of forward transport using a common CO 2 flux field  Use of non-surface CO 2 data in the cross- validation of atmospheric CO 2 inversion models Focus on differences in forward simulations Methodology…  Single (common) CO 2 flux field generated from the Baker et al. 2006 inter-comparison study inserted in the ATMs  Model CO 2 concentration field sampled appropriately to compare to available CO 2 measurements

3. Available CO 2 measurements…  Non-Surface CO 2 Airborne Data Archive : Consists of measurements from 39 aircraft campaigns 27 short, intensive campaigns E.G. COBRA 2000, 2003, 2004 (Gerbig et al. 2003, Lin et al. 2006 and others), PEM-WEST A/B (Anderson et al. 1996, Hoell et al. 1997), PEM-TROPICS A/B (Hoell et al. 1999, Raper et al. 2001), BIBLE A (Machida et al. 2003) ), CRYSTAL (Xueref et al. 2004) and others 12 long-term, regular campaigns E.G. Matsueda et al. (1999), NOAA/GMA profile data (Stephens et al. in press), Cape Grim profile data (Pak 2000, Langenfelds et al. 1996, 1999), CARIBIC (Brenninkmeijer et al. 2005) and others

4. Available CO 2 measurements…  Non-Surface CO 2 Airborne Data Archive Temporal Coverage: 1987 – 2004 Surface  Lower Stratosphere –Majority of data within the free troposphere Reasonable Global Coverage –Data concentrated over the Pacific Ocean and North America Altitude Variation (surf - ~21km) Surf 21,6 km

5. Inter-comparison project: Current Status… All participating models required to:  Re-grid flux fields onto respective model grids  Run a forward simulation with analysed meteorology from 1988 – 2003 (or part thereof) Use of ‘real winds’  Sample the model CO 2 conc. field at specified spatio-temporal locations

6. Inter-comparison project: Current Status…  Currently there are 4 participating ATMs LSCE: LMDz (P. Bousquet) CSIRO: CCAM (C. Pickett – Heaps & R. Law) NIES: CCSR (P. Patra) (Not used yet !) JMA: CTDM (T. Maki) Colorado State Univ. will hopefully become a future participant  Current results are very preliminary (further analysis planed for this year)

7. Inter-comparison results to date… Analysis to date based on profile data:  Cape Grim Profile Data –Monthly vertical profiles over Cape Grim from 1991 – 2000, surface - ~7000m  CAR Profile Data –Weekly vertical profiles flown over CAR from 1992 – 2002, surface - ~7000m  For each profile… RMS error and mean model bias (average residual) are calculated

8. CCAM LMDz CTDM CCAM LMDz CTDM Inter-comparison Results: RMS error/Model Bias average statistics & time-series CAR

9. Inter-comparison Results: RMS error/Resid seasonality CAR  NOTE: Strong seasonality in RMS error in all forward simulations RMS error vs. Month Bias vs. Month CCAM LMDz CTDM 0 6 3 -6 6 0 JanDec Jan Dec

10. Inter-comparison Results: Seasonal Mean Residual Profiles CAR CI:Confidence Interval of mean model bias for different levels of the atmosphere  NOTE: Seasonal errors in the vertical gradient during summer (June – August) CCAM CI LMDz CI CTDM CI -5 Jun-Jul-AugDec-Jan-Feb 5 -44

11. Inter-comparison Results: RMS error/Model Bias average statistics & time-series CAPE GRIM CCAM LMDz CTDM CCAM LMDz CTDM

12. Inter-comparison Results: RMS error/Resid seasonality Cape Grim  NOTE: Strong seasonality in model bias within CCAM/CTDM fwd simul. but reduced seasonality in the LMDz fwd simul. Bias vs. MonthRMS error vs. Month CCAM LMDz CTDM 0 3 1.5 -3 0 Jan Dec Jan Dec

13. Inter-comparison Results: Seasonal Mean Residual Profiles Cape Grim CCAM CI LMDz CI CTDM CI Jun-Jul-Aug Dec-Jan-Feb Mar-Apr-Mai Sep-Oct-Nov

14. (VERY PRELIMINARY Inter-comparison Results: Variation across four models Non-Surface CO 2 Airborne Data Archive (VERY PRELIMINARY!) RANGE: 0.05ppm – >1.7ppm (9,000m – 12,000m) RANGE: 0.04ppm – >2ppm (6000m – 9000m)

15. Future Plans…  Solve current problems in sampling conc. field with certain ATMs Inclusion of results from more models  Extend inter-comparison to the entire upper-air archive  Perform extensive analysis of the Non- Surface CO 2 Airborne Data Archive Statistical/Climatological analysis

16. THANKS TO:  The LSCE & CMAR Dr Peter Rayner, Dr Rachel Law, Dr Philippe Ciais, Dr Philippe Bousquet & Dr Philippe Peylin  All inter-comparison participants  All measurement campaign PIs who have contributed to the data archive  AND… sincere apologies that I am not able to attend the TRANSCOM meeting this year