1. Thomas Ackerman Roger Marchand University of Washington

2.  As we move towards higher resolution models with more realistic simulations of cloud processes and cloud properties, how do we evaluate model cloud properties?  What are the metrics?  How do know we are improving those metrics?

3.  Occurrence in space and time – cloud fraction  Cloud top height  Optical depth – an optical (radiation) measure of the total condensed water and ice in a cloud  Statistical distributions of these quantities

4. CloudSat – 3 mm radar NASA A-Train, launched 2006 Profiles of cloud reflectivity MISR – multi-angle radiometer NASA Terra, launched 1999 Cloud height and optical depth ARM sites – multiple instruments Established 1996 – 1998 Cloud profiles and integrated properties

5. Cyclone Nargis in the Bay of Bengal before landfall in Myanmar MODIS image CloudSat curtain along red line

6. MMFAugust Composite

11.  MMF captures general cloud structure and seasonal movement  MMF generally overproduces convective cloud  Too much high cloud and too optically thick  MMF underpredicts BL cloud (Stratus, Trade Cu)  Produces too much precipitation  Simulated Radar reflectivity values are too high  Too much drizzle

12.  CloudSat has limited temporal coverage  ARM radar has limited spatial coverage  Combine them to provide detailed regional data  Work in progress  Detailed comparison of radar signals  Apply to simulations in TWP

13.  MISR measures stereo cloud-top height and cloud optical depth  Plot as 2D joint histogram  MISR simulator incorporated into MMF

14. 64 or 128 Columns 2°2° 2.5° 3-month MMF runs Increasing resolution Control run 4 km horizontal 64 columns 26 vertical layers Test A 1 km horizontal 64 & 128 columns 26 vertical layers Test B 1 km horizontal 64 columns 52 vertical layers Run on SDSC Datastar with support from CMMAP

17.  Going from 4 km to 1 km reduced low cloud amount.  Much (but not all) due to dissipation of “stratofogulus”  Generally, little change in amount of low cloud with optical depths less than 10.  Going from 4 km to 1 km and vertical resolution to 52 levels (50 in CRM) resulted in …  Small increase in the amount of low-level cloud relative to the simulations with 4 km horizontal resolution.  Increase in cloud with optical depths less than 10 (better agreement with MISR observational data)  Stratocumulus zones show a significant improvement in cloud top height.  BUT  Total amount of model low cloud remains too low  Too much low cloud with optical depths larger than 23 (the largest two optical- depth bins).

18.  New instruments well suited to evaluating MMF  Model spatial resolution matches sensors  Simulator approach easy to implement in MMF  Provide new metrics  Profiles of cloud occurrence  Optical depth – cloud top height joint histograms  Test model improvements against these same metrics

19. Thank you for your attention!

20.  Mace, G. G., Q. Zhang, M. Vaughan, R. Marchand, G. Stephens, C. Trepte, and D. Winker (2009), A description of hydrometeor layer occurrence statistics derived from the first year of merged Cloudsat and CALIPSO data, J. Geophys. Res., 114, D00A26, doi:10.1029/2007JD009755.  McFarlane, S. A., J. H. Mather, and T. P. Ackerman, 2007: Analysis of tropical radiative heating profiles: A comparison of models and observations, J. Geophys. Res., 112, D14218, doi:10.1029/2006JD008290  Marchand, R. T., J. Haynes, G. G. Mace, T. P. Ackerman, and G. Stephens, 2009: A comparison of CloudSat cloud radar observations with simulated cloud radar output from the Multiscale Modeling Framework global climate model, J. Geophys. Res., 114, D00A20, doi:10.1029/2008JD009790  Marchand, R. T., and T. P. Ackerman, 2009: Analysis of the MMF global climate model using ISCCP and MISR histograms of cloud top height and optical depth, manuscript in preparation  Marchand, R. T., T. P. Ackerman, M. Smyth, P. Hubanks, S. Platnick, and W. Rossow, 2009: A comparison of cloud top height and optical depth histograms from MISR, ISCCP, and MODIS, manuscript in preparation Research supported by DOE ARM, NASA, and CMMAP