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The Pre-VOCALS Model Assessment (PreVOCA)

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

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The Pre-VOCALS Model Assessment (PreVOCA)

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  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. PreVOCA 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.html

  3. PreVOCA observational data

  4. Analysis Monthly mean Diurnal cycle Synoptic variability

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

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

  7. Low Cloud Fraction

  8. Liquid Water Path (g m-2)

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

  10. UChile WRF COAMPS IPRC Obs pinv UKMO EC-oper NCEP

  11. 85W sounding comparisons Global forecast Climate Regional October soundings at IMET BUOY location Sharpness of inversion challenges even the highest-resolution models

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

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

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

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

  16. Operational models capture synoptic variability quite well.

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

  18. Many regional models are struggling against mean biases

  19. 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 reff 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).

  20. 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.

  21. 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).

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