1. The Pre-VOCALS Model Assessment (PreVOCA) Matt Wyant Chris Bretherton Rob Wood, Univ. of Washington Roberto Mechoso, UCLA...and most important... Participating modeling groups

2. GOAL: Assess the forecast skill and biases of global/ regional model simulations of SE Pacific boundary-layer clouds on diurnal and longer timescales. WHAT? Daily hindcasts for October 2006 over the SE Pacific. WHO? 14 modeling groups using regional and global models, including climate models run in forecast mode. STATUS: Results near submission. NEXT: A second phase focusing more on cloud-aerosol interaction and chemical transport based on VOCALS- REx period Oct-Nov 2008 will be announced shortly. www.atmos.washington.edu/~robwood/PreVOCA/index.htmlPreVOCA

3. ModelLevelsResolution [km] (inner domain) NRL COAMPS42 81 (27) COLA RSM2850 IPRC Reg_CM (IRAM)28~25 PNNL (WRF-Chem)4445 (15) UCLA (WRF)3445 (15) U. Chile (WRF)4345 ECMWF oper. 3-12h forecast91~25 ECMWF 5-day forecast91~40 ECMWF coupled fcst ensemble62~125 GMAO GEOS-5 DAS72~56 JMA 24-30h forecast60~60 NCEP oper. 12-36h forecast64~38 UKMO oper. 12-36h forecast50~40 LMDZ3850 NCAR CAM3.5/626/30250 GFDL24250

4. PreVOCA observational data ISCCP FDRadiative fluxes at surface, TOA TMILWP, WVP AMSRLWP, WVP MODISCloud fraction, optical depth, droplet size, cloud-top height NOAA ESRL Stratus Cruises Temperature, moisture soundings, surface fluxes, drizzle properties, aerosols QuikSCATOcean surface winds NCEP ReanalysisVertical velocity CALIPSOCloud top height COSMICTemperature soundings CloudSatDrizzle properties

5. Analysis Monthly mean Diurnal cycle Synoptic variability

6. Oct 2006 10 m vector wind (m s -1 ) - models agree fairly well Global Regional

7. Omega at 850 hPa (Pa s -1 ) - also not too bad Global Regional

8. Low Cloud Fraction

9. Liquid Water Path (g m -2 )

10. SW down at surface (W m -2 )

11. NCEPUKMOEC-oper IPRCCOAMPSUChile WRF Obs pinv

12. October soundings at IMET BUOY location 85W sounding comparisons Regional Global forecast Climate Sharpness of inversion challenges even the highest-resolution models

13. Mean Boundary Layer Depth Along 20S Most models have too low an inversion near the coast.

14. Diurnal Composite LWP 0 12 6 24 18 Hour (local) TMI climo from Wood et al. (2002) GRL

15. Diurnal Composite Low Cloud Fraction 0 12 6 24 18 Hour (local) EECRA compiled by Sungsu Park

16. ‘Upsidence’ Wave w at 800hPa MM5 November 14-28 2001 Garreaud and Munoz (2004) 20S 75W 20S 80W 20S 85W

17. Operational models capture synoptic variability quite well.

18. CAM and GFDL are also capturing the main cloud transition.

19. Many regional models are struggling against mean biases

20. From PreVOCA to VOCA... VOCA: Similar protocol to preVOCA using REx observations from 15 Oct -15 Nov 2008 More focus on chemical transport, aerosol concentrations and r eff vs. in-situ and CALIPSO data. We will send out a detailed protocol in summer 2009. All modeling groups are welcome (with or without chemical transport modeling capability).

21. Conclusions Much scatter in PBL/Sc properties, esp. among regional models: an issue for aerosol-cloud interaction? Mean biases are the most important error. UKMO and ECMWF models performed best overall, correctly capturing most geographic and temporal variations in PBL depth/structure and cloud cover. VOCALS SE Pacific datasets are wonderful tools for assessing and improving cloud and aerosol simulations. We welcome other models to participate in VOCA.

22. VOCALS The VAMOS Ocean-Cloud-Atmosphere-Land Study A multiyear study of boundary layer cloud, aerosol, and upper ocean heat/constituent transport WHOI stratus flux-reference buoy at 20S 85W (2000+) Annual instrumented cruises in austral spring (starting with EPIC 2001 stratocumulus cruise). Regional Experiment (REx) in Oct.-Nov. 2008, including 4 aircraft based in northern Chile, two ships, coastal site: Satellite data analysis of cloud properties Atmosphere and ocean modeling (LES to global).