1. RMS 18 th June 2003 Evaluating moisture in the Hadley Centre Climate Model using 20 years of satellite data Richard Allan Environmental Systems Science Centre, University of Reading Thanks to Mark Ringer, Tony Slingo and John Edwards

2. RMS 18 th June 2003 INTRODUCTION –Using moisture to evaluate/improve climate models »Development/improvement of parametrizations »Evaluation of moist processes and feedbacks –RH distribution and variability crucial to water vapour/cloud feedback –HadAM3 Simulations of UTH radiances –Evaluation of HadAM3 using satellite data

3. RMS 18 th June 2003 Water vapour and OLR CWV (kgm -2 ) 270 280 290 300 Surface Temperature (K) (1) Clausius Clapeyron (2) Radiative Transfer 0 60_ 30_

4. RMS 18 th June 2003 dOLR/dRH (Wm -2 % -1 ) RH (%) Sensitivity of OLR to RH (using ERA-15) (Allan et al. 1999, QJ, 125, 2103) - Column integrated water vapour - Upper tropospheric moisture ??

5. RMS 18 th June 2003 Water vapour feedback: recent advances (1) Insensitive to resolution (Ingram 2002, J Climate, 15, 917-921) (2) Consistent with observations following post-Pinatubo cooling (Soden et al 2002, Science, 296, 727)

6. RMS 18 th June 2003 Is water vapour feedback really consistent between models? dOLRc/dTs ~ 2 Wm -2 K -1 dOLR/dTs uncertain (Cess et al. 1990, JGR, 95, 16601) Allan et al. 2002, JGR, 107(D17), 4329. doi: 10.1029/2001JD001131. - Temperature lapse rate (Gaffen et al 2000, Science, 287, 1242) - Tropical Cloudiness (Wielicki et al, 2002, Science, 295, 841)

7. RMS 18 th June 2003 Large changes in OLR from 7 independent satellite instruments (Wielicki et al, 2002) HadAM3/HadCM3 cannot simulate recent changes in cloudy portion of tropical radiation budget even when current climate forcings are applied (Allan & Slingo 2002, GRL, 29(7), doi: 10.1029/2001GL014620)

8. RMS 18 th June 2003 EXPERIMENTS [Allan et al. 2003, accepted QJ] Ensemble of AMIP-type HadAM3 runs - Standard res, 19 levels, 1978-1999. HadISST SST/sea ice forcing - Radiance code [see Ringer et al., 2002, QJ, 129, 1169-1190] - Modified clear-sky diagnostics: OLRc & water vapour radiance -Additional all-forcings run SATELLITE DATA -- column water vapour, CWV [SMMR 1979-84, SSM/I 1987-99] -- clear-sky OLR [ERBS 1985-89, ScaRaB 1994/5, CERES 1998] -- Water Vapour channel brightness temperature, T 6.7 [HIRS 1979-1998]

9. RMS 18 th June 2003 Climatological mean over 60 o S-60 o N oceans

10. RMS 18 th June 2003 OBSERVATIONS HadAM3 COLUMN WATER VAPOUR JJA HadAM3-OBS differenceDJF

11. RMS 18 th June 2003 Interannual variability of Column Water vapour 1980 1985 1990 1995

12. RMS 18 th June 2003 Can we use reanalysis CWV? ERA-40

13. RMS 18 th June 2003 Info on upper tropospheric water vapour T 6.7 500mb omega Clear-sky OLR

14. RMS 18 th June 2003 Model-obs differences & Clear-sky Sampling T 6.7 OLRc Type II HadAM3-OBS Type-I

15. RMS 18 th June 2003 Interannual monthly anomalies: tropical oceans

16. RMS 18 th June 2003 (+additional forcings)

17. RMS 18 th June 2003 Clear-sky sampling: interannual variability Light blue: Type I (weighted by clear-sky fraction) Dark Blue: Type II (unweighted mean)

18. RMS 18 th June 2003 EOF analysis of spatio- temporal variability in water vapour radiance

19. RMS 18 th June 2003 Using ERA40 clear- sky OLR to evaluate dynamical regimes ERA40-CERES similar ERA40 < CERES ERA40 minus CERES clear-sky OLR (January-August 1998)

20. RMS 18 th June 2003 Summary Simulations of satellite brightness temperatures Consistent decadal variability suggests small DRH realistic Clear-sky sampling important for infrared channel climatologies but not interannual variability Overactive circulation in HadAM3? Note of caution: –can multiple satellite intercalibration artificially remove decadal trends? –Changes in atmos. T also influences T6.7 decadal fluctuations